register interest

Dr Nicola A Burgess-Brown

Research Area: Cell and Molecular Biology
Technology Exchange: Drug discovery and Protein interaction
Scientific Themes: Protein Science & Structural Biology
Keywords: Biotechnology, protein expression, high-throughput methods, membrane proteins, structural genomics
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The Biotechnology group at the SGC in Oxford is primarily responsible for generating the pipeline of clones and determining which proteins are expressed in a soluble and stable form suitable for structural and functional studies. We have developed and optimised protocols for high-throughput ligation independent cloning, test expression and purification, large scale expression, protein production and characterisation by mass spectrometry. The target list stems from protein areas of interest to the Biology PIs within the SGC and includes epigenetics, kinases, organelle biogenesis, growth factor signalling, DNA-RNA processing and IMPs. The support and responsiveness we provide to the epigenetics and the soluble and IMP structural projects, helps to advance the knowledge in these fields and our rate of success.

The platform established by the Biotechnology team, has enabled the site at Oxford to generate 400 novel human protein structures and 2 integral membrane protein structures to date. The group collaborates and interacts closely with the other SGC teams, to develop methods for increasing protein expression, parallel processing and driving output. To date, we have been using both E. coli and baculovirus/insect cell expression systems for protein production. However initiating new method development projects is an important aspect of our role within the organisation to ensure we find ways of producing the most challenging proteins on the target list, many of which are also of high value to the scientific community. Consequently, we are currently setting up platforms for producing proteins in Saccharomyces cerevisiae and mammalian cells, including BacMam technology. We may also explore other expression systems in the future. In addition to enhancing protein expression levels, we also aim to reduce our cost per structure by seeking alternative cheaper reagents, consumables and increasing throughput further by miniaturising the processes and increasing automation where possible. Discovering ways to successfully produce the most challenging human proteins would open many doors to our long-term goals as an organisation of understanding how proteins function independently, with partners and also how they interact with drugs.

There are no collaborations listed for this principal investigator.

Dong YY, Wang H, Pike ACW, Cochrane SA, Hamedzadeh S, Wyszyński FJ, Bushell SR, Royer SF, Widdick DA, Sajid A et al. 2018. Structures of DPAGT1 Explain Glycosylation Disease Mechanisms and Advance TB Antibiotic Design. Cell, 175 (4), pp. 1045-1058.e16. | Show Abstract | Read more

Protein N-glycosylation is a widespread post-translational modification. The first committed step in this process is catalysed by dolichyl-phosphate N-acetylglucosamine-phosphotransferase DPAGT1 (GPT/E.C. 2.7.8.15). Missense DPAGT1 variants cause congenital myasthenic syndrome and disorders of glycosylation. In addition, naturally-occurring bactericidal nucleoside analogues such as tunicamycin are toxic to eukaryotes due to DPAGT1 inhibition, preventing their clinical use. Our structures of DPAGT1 with the substrate UDP-GlcNAc and tunicamycin reveal substrate binding modes, suggest a mechanism of catalysis, provide an understanding of how mutations modulate activity (thus causing disease) and allow design of non-toxic "lipid-altered" tunicamycins. The structure-tuned activity of these analogues against several bacterial targets allowed the design of potent antibiotics for Mycobacterium tuberculosis, enabling treatment in vitro, in cellulo and in vivo, providing a promising new class of antimicrobial drug.

Bulbrook D, Brazier H, Mahajan P, Kliszczak M, Fedorov O, Marchese FP, Aubareda A, Chalk R, Picaud S, Strain-Damerell C et al. 2018. Tryptophan-Mediated Interactions between Tristetraprolin and the CNOT9 Subunit Are Required for CCR4-NOT Deadenylase Complex Recruitment. J Mol Biol, 430 (5), pp. 722-736. | Show Abstract | Read more

The zinc-finger protein tristetraprolin (TTP) binds to AU-rich elements present in the 3' untranslated regions of transcripts that mainly encode proteins of the inflammatory response. TTP-bound mRNAs are targeted for destruction via recruitment of the eight-subunit deadenylase complex "carbon catabolite repressor protein 4 (CCR4)-negative on TATA-less (NOT)," which catalyzes the removal of mRNA poly-(A) tails, the first obligatory step in mRNA decay. Here we show that a novel interaction between TTP and the CCR4-NOT subunit, CNOT9, is required for recruitment of the deadenylase complex. In addition to CNOT1, CNOT9 is now included in the identified CCR4-NOT subunits shown to interact with TTP. We find that both the N- and C-terminal domains of TTP are involved in an interaction with CNOT9. Through a combination of SPOT peptide array, site-directed mutagenesis, and bio-layer interferometry, we identified several conserved tryptophan residues in TTP that serve as major sites of interaction with two tryptophan-binding pockets of CNOT9, previously found to interact with another modulator GW182. We further demonstrate that these interactions are also required for recruitment of the CCR4-NOT complex and TTP-directed decay of an mRNA containing an AU-rich element in its 3'-untranslated region. Together the results reveal new molecular details for the TTP-CNOT interaction that shape an emerging mechanism whereby TTP targets inflammatory mRNAs for deadenylation and decay.

Bradley AR, Echalier A, Fairhead M, Strain-Damerell C, Brennan P, Bullock AN, Burgess-Brown NA, Carpenter EP, Gileadi O, Marsden BD et al. 2017. The SGC beyond structural genomics: redefining the role of 3D structures by coupling genomic stratification with fragment-based discovery. Essays Biochem, 61 (5), pp. 495-503. | Show Abstract | Read more

The ongoing explosion in genomics data has long since outpaced the capacity of conventional biochemical methodology to verify the large number of hypotheses that emerge from the analysis of such data. In contrast, it is still a gold-standard for early phenotypic validation towards small-molecule drug discovery to use probe molecules (or tool compounds), notwithstanding the difficulty and cost of generating them. Rational structure-based approaches to ligand discovery have long promised the efficiencies needed to close this divergence; in practice, however, this promise remains largely unfulfilled, for a host of well-rehearsed reasons and despite the huge technical advances spearheaded by the structural genomics initiatives of the noughties. Therefore the current, fourth funding phase of the Structural Genomics Consortium (SGC), building on its extensive experience in structural biology of novel targets and design of protein inhibitors, seeks to redefine what it means to do structural biology for drug discovery. We developed the concept of a Target Enabling Package (TEP) that provides, through reagents, assays and data, the missing link between genetic disease linkage and the development of usefully potent compounds. There are multiple prongs to the ambition: rigorously assessing targets' genetic disease linkages through crowdsourcing to a network of collaborating experts; establishing a systematic approach to generate the protocols and data that comprise each target's TEP; developing new, X-ray-based fragment technologies for generating high quality chemical matter quickly and cheaply; and exploiting a stringently open access model to build multidisciplinary partnerships throughout academia and industry. By learning how to scale these approaches, the SGC aims to make structures finally serve genomics, as originally intended, and demonstrate how 3D structures systematically allow new modes of druggability to be discovered for whole classes of targets.

Tumber A, Nuzzi A, Hookway ES, Hatch SB, Velupillai S, Johansson C, Kawamura A, Savitsky P, Yapp C, Szykowska A et al. 2017. Potent and Selective KDM5 Inhibitor Stops Cellular Demethylation of H3K4me3 at Transcription Start Sites and Proliferation of MM1S Myeloma Cells. Cell Chem Biol, 24 (3), pp. 371-380. | Show Abstract | Read more

Methylation of lysine residues on histone tail is a dynamic epigenetic modification that plays a key role in chromatin structure and gene regulation. Members of the KDM5 (also known as JARID1) sub-family are 2-oxoglutarate (2-OG) and Fe2+-dependent oxygenases acting as histone 3 lysine 4 trimethyl (H3K4me3) demethylases, regulating proliferation, stem cell self-renewal, and differentiation. Here we present the characterization of KDOAM-25, an inhibitor of KDM5 enzymes. KDOAM-25 shows biochemical half maximal inhibitory concentration values of <100 nM for KDM5A-D in vitro, high selectivity toward other 2-OG oxygenases sub-families, and no off-target activity on a panel of 55 receptors and enzymes. In human cell assay systems, KDOAM-25 has a half maximal effective concentration of ∼50 μM and good selectivity toward other demethylases. KDM5B is overexpressed in multiple myeloma and negatively correlated with the overall survival. Multiple myeloma MM1S cells treated with KDOAM-25 show increased global H3K4 methylation at transcriptional start sites and impaired proliferation.

Grieben M, Pike ACW, Shintre CA, Venturi E, El-Ajouz S, Tessitore A, Shrestha L, Mukhopadhyay S, Mahajan P, Chalk R et al. 2017. Structure of the polycystic kidney disease TRP channel Polycystin-2 (PC2). Nat Struct Mol Biol, 24 (2), pp. 114-122. | Show Abstract | Read more

Mutations in either polycystin-1 (PC1 or PKD1) or polycystin-2 (PC2, PKD2 or TRPP1) cause autosomal-dominant polycystic kidney disease (ADPKD) through unknown mechanisms. Here we present the structure of human PC2 in a closed conformation, solved by electron cryomicroscopy at 4.2-Å resolution. The structure reveals a novel polycystin-specific 'tetragonal opening for polycystins' (TOP) domain tightly bound to the top of a classic transient receptor potential (TRP) channel structure. The TOP domain is formed from two extensions to the voltage-sensor-like domain (VSLD); it covers the channel's endoplasmic reticulum lumen or extracellular surface and encloses an upper vestibule, above the pore filter, without blocking the ion-conduction pathway. The TOP-domain fold is conserved among the polycystins, including the homologous channel-like region of PC1, and is the site of a cluster of ADPKD-associated missense variants. Extensive contacts among the TOP-domain subunits, the pore and the VSLD provide ample scope for regulation through physical and chemical stimuli.

Montgomery AB, Kopec J, Shrestha L, Thezenas M-L, Burgess-Brown NA, Fischer R, Yue WW, Venables PJ. 2016. Crystal structure of Porphyromonas gingivalis peptidylarginine deiminase: implications for autoimmunity in rheumatoid arthritis ANNALS OF THE RHEUMATIC DISEASES, 75 (6), pp. 1255-1261. | Read more

Johansson C, Velupillai S, Tumber A, Szykowska A, Hookway ES, Nowak RP, Strain-Damerell C, Gileadi C, Philpott M, Burgess-Brown N et al. 2016. Structural analysis of human KDM5B guides histone demethylase inhibitor development. Nat Chem Biol, 12 (7), pp. 539-545. | Show Abstract | Read more

Members of the KDM5 (also known as JARID1) family are 2-oxoglutarate- and Fe(2+)-dependent oxygenases that act as histone H3K4 demethylases, thereby regulating cell proliferation and stem cell self-renewal and differentiation. Here we report crystal structures of the catalytic core of the human KDM5B enzyme in complex with three inhibitor chemotypes. These scaffolds exploit several aspects of the KDM5 active site, and their selectivity profiles reflect their hybrid features with respect to the KDM4 and KDM6 families. Whereas GSK-J1, a previously identified KDM6 inhibitor, showed about sevenfold less inhibitory activity toward KDM5B than toward KDM6 proteins, KDM5-C49 displayed 25-100-fold selectivity between KDM5B and KDM6B. The cell-permeable derivative KDM5-C70 had an antiproliferative effect in myeloma cells, leading to genome-wide elevation of H3K4me3 levels. The selective inhibitor GSK467 exploited unique binding modes, but it lacked cellular potency in the myeloma system. Taken together, these structural leads deliver multiple starting points for further rational and selective inhibitor design.

Bavetsias V, Lanigan RM, Ruda GF, Atrash B, McLaughlin MG, Tumber A, Mok NY, Le Bihan Y-V, Dempster S, Boxall KJ et al. 2016. 8-Substituted Pyrido[3,4-d]pyrimidin-4(3H)-one Derivatives As Potent, Cell Permeable, KDM4 (JMJD2) and KDM5 (JARID1) Histone Lysine Demethylase Inhibitors. J Med Chem, 59 (4), pp. 1388-1409. | Show Abstract | Read more

We report the discovery of N-substituted 4-(pyridin-2-yl)thiazole-2-amine derivatives and their subsequent optimization, guided by structure-based design, to give 8-(1H-pyrazol-3-yl)pyrido[3,4-d]pyrimidin-4(3H)-ones, a series of potent JmjC histone N-methyl lysine demethylase (KDM) inhibitors which bind to Fe(II) in the active site. Substitution from C4 of the pyrazole moiety allows access to the histone peptide substrate binding site; incorporation of a conformationally constrained 4-phenylpiperidine linker gives derivatives such as 54j and 54k which demonstrate equipotent activity versus the KDM4 (JMJD2) and KDM5 (JARID1) subfamily demethylases, selectivity over representative exemplars of the KDM2, KDM3, and KDM6 subfamilies, cellular permeability in the Caco-2 assay, and, for 54k, inhibition of H3K9Me3 and H3K4Me3 demethylation in a cell-based assay.

Montgomery AB, Kopec J, Shrestha L, Thezenas M-L, Burgess-Brown NA, Fischer R, Yue WW, Venables PJ. 2016. Crystal structure of Porphyromonas gingivalis peptidylarginine deiminase: implications for autoimmunity in rheumatoid arthritis. Ann Rheum Dis, 75 (6), pp. 1255-1261. | Show Abstract | Read more

BACKGROUND: Periodontitis (PD) is a known risk factor for rheumatoid arthritis (RA) and there is increasing evidence that the link between the two diseases is due to citrullination by the unique bacterial peptidylarginine deiminase (PAD) enzyme expressed by periodontal pathogen Pophyromonas gingivalis (PPAD). However, the precise mechanism by which PPAD could generate potentially immunogenic peptides has remained controversial due to lack of information about the structural and catalytic mechanisms of the enzyme. OBJECTIVES: By solving the 3D structure of PPAD we aim to characterise activity and elucidate potential mechanisms involved in breach of tolerance to citrullinated proteins in RA. METHODS: PPAD and a catalytically inactive mutant PPAD(C351A) were crystallised and their 3D structures solved. Key residues identified from 3D structures were examined by mutations. Fibrinogen and α-enolase were incubated with PPAD and P. gingivalis arginine gingipain (RgpB) and citrullinated peptides formed were sequenced and quantified by mass spectrometry. RESULTS: Here, we solve the crystal structure of a truncated, highly active form of PPAD. We confirm catalysis is mediated by the following residues: Asp130, His236, Asp238, Asn297 and Cys351 and show Arg152 and Arg154 may determine the substrate specificity of PPAD for C-terminal arginines. We demonstrate the formation of 37 C-terminally citrullinated peptides from fibrinogen and 11 from α-enolase following incubation with tPPAD and RgpB. CONCLUSIONS: PPAD displays an unequivocal specificity for C-terminal arginine residues and readily citrullinates peptides from key RA autoantigens. The formation of these novel citrullinated peptides may be involved in breach of tolerance to citrullinated proteins in RA.

Dong YY, Pike ACW, Mackenzie A, McClenaghan C, Aryal P, Dong L, Quigley A, Grieben M, Goubin S, Mukhopadhyay S et al. 2015. K2P channel gating mechanisms revealed by structures of TREK-2 and a complex with Prozac. Science, 347 (6227), pp. 1256-1259. | Show Abstract | Read more

TREK-2 (KCNK10/K2P10), a two-pore domain potassium (K2P) channel, is gated by multiple stimuli such as stretch, fatty acids, and pH and by several drugs. However, the mechanisms that control channel gating are unclear. Here we present crystal structures of the human TREK-2 channel (up to 3.4 angstrom resolution) in two conformations and in complex with norfluoxetine, the active metabolite of fluoxetine (Prozac) and a state-dependent blocker of TREK channels. Norfluoxetine binds within intramembrane fenestrations found in only one of these two conformations. Channel activation by arachidonic acid and mechanical stretch involves conversion between these states through movement of the pore-lining helices. These results provide an explanation for TREK channel mechanosensitivity, regulation by diverse stimuli, and possible off-target effects of the serotonin reuptake inhibitor Prozac.

England KS, Tumber A, Krojer T, Scozzafava G, Ng SS, Daniel M, Szykowska A, Che K, von Delft F, Burgess-Brown NA et al. 2014. Optimisation of a triazolopyridine based histone demethylase inhibitor yields a potent and selective KDM2A (FBXL11) inhibitor. Medchemcomm, 5 (12), pp. 1879-1886. | Show Abstract | Read more

A potent inhibitor of the JmjC histone lysine demethylase KDM2A (compound 35, pIC50 7.2) with excellent selectivity over representatives from other KDM subfamilies has been developed; the discovery that a triazolopyridine compound binds to the active site of JmjC KDMs was followed by optimisation of the triazole substituent for KDM2A inhibition and selectivity.

Philpott M, Rogers CM, Yapp C, Wells C, Lambert J-P, Strain-Damerell C, Burgess-Brown NA, Gingras A-C, Knapp S, Müller S. 2014. Assessing cellular efficacy of bromodomain inhibitors using fluorescence recovery after photobleaching. Epigenetics Chromatin, 7 (1), pp. 14. | Show Abstract | Read more

BACKGROUND: Acetylation of lysine residues in histone tails plays an important role in the regulation of gene transcription. Bromdomains are the readers of acetylated histone marks, and, consequently, bromodomain-containing proteins have a variety of chromatin-related functions. Moreover, they are increasingly being recognised as important mediators of a wide range of diseases. The first potent and selective bromodomain inhibitors are beginning to be described, but the diverse or unknown functions of bromodomain-containing proteins present challenges to systematically demonstrating cellular efficacy and selectivity for these inhibitors. Here we assess the viability of fluorescence recovery after photobleaching (FRAP) assays as a target agnostic method for the direct visualisation of an on-target effect of bromodomain inhibitors in living cells. RESULTS: Mutation of a conserved asparagine crucial for binding to acetylated lysines in the bromodomains of BRD3, BRD4 and TRIM24 all resulted in reduction of FRAP recovery times, indicating loss of or significantly reduced binding to acetylated chromatin, as did the addition of known inhibitors. Significant differences between wild type and bromodomain mutants for ATAD2, BAZ2A, BRD1, BRD7, GCN5L2, SMARCA2 and ZMYND11 required the addition of the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) to amplify the binding contribution of the bromodomain. Under these conditions, known inhibitors decreased FRAP recovery times back to mutant control levels. Mutation of the bromodomain did not alter FRAP recovery times for full-length CREBBP, even in the presence of SAHA, indicating that other domains are primarily responsible for anchoring CREBBP to chromatin. However, FRAP assays with multimerised CREBBP bromodomains resulted in a good assay to assess the efficacy of bromodomain inhibitors to this target. The bromodomain and extraterminal protein inhibitor PFI-1 was inactive against other bromodomain targets, demonstrating the specificity of the method. CONCLUSIONS: Viable FRAP assays were established for 11 representative bromodomain-containing proteins that broadly cover the bromodomain phylogenetic tree. Addition of SAHA can overcome weak binding to chromatin, and the use of tandem bromodomain constructs can eliminate masking effects of other chromatin binding domains. Together, these results demonstrate that FRAP assays offer a potentially pan-bromodomain method for generating cell-based assays, allowing the testing of compounds with respect to cell permeability, on-target efficacy and selectivity.

Yu W, Eram MS, Hajian T, Szykowska A, Burgess-Brown N, Vedadi M, Brown PJ. 2014. A scintillation proximity assay for histone demethylases. Anal Biochem, 463 pp. 54-60. | Show Abstract | Read more

Covalent modifications, such as methylation and demethylation of lysine residues in histones, play important roles in chromatin dynamics and the regulation of gene expression. The lysine demethylases (KDMs) catalyze the demethylation of lysine residues on histone tails and are associated with diverse human diseases, including cancer, and are therefore proposed as targets for the therapeutic modulation of gene transcription. High-throughput assays have been developed to find inhibitors of KDMs, most of which are fluorescence-based assays. Here we report the development of a coupled scintillation proximity assay (SPA) for 3 KDMs: KDM1A (LSD1), KDM3A (JMJD1A), and KDM4A (JMJD2A). In this assay methylated peptides are first demethylated by a KDM, and a protein methyltransferase (PMT) is added to methylate the resulting peptide with tritiated S-(5'-adenosyl)-l-methionine. The enzyme activities were optimized and kinetic parameters were determined. These robust coupled assays are suitable for screening KDMs in 384-well format (Z' factors of 0.70-0.80), facilitating discovery of inhibitors in the quest for cancer therapeutics.

Cited:

22

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Guetzoyan L, Ingham RJ, Nikbin N, Rossignol J, Wolling M, Baumert M, Burgess-Brown NA, Strain-Damerell CM, Shrestha L, Brennan PE et al. 2014. Machine-assisted synthesis of modulators of the histone reader BRD9 using flow methods of chemistry and frontal affinity chromatography MEDCHEMCOMM, 5 (4), pp. 540-546. | Show Abstract | Read more

A combination of conventional organic synthesis, remotely monitored flow synthesis and bioassay platforms, were used for the evaluation of novel inhibitors targeting bromodomains outside the well-studied bromodomain and extra terminal (BET) family, here exemplified by activity measurements on the bromodomain of BRD9 protein, a component of some tissue-specific SWi/SNF chromatin remodelling complexes. The Frontal Affinity Chromatography combined with Mass Spectrometry (FAC-MS) method proved to be reliable and results correlated well with an independent thermal shift assay. © 2014 the Partner Organisations.

Mahajan P, Strain-Damerell C, Gileadi O, Burgess-Brown NA. 2014. Medium-Throughput Production of Recombinant Human Proteins: Protein Production in Insect Cells Methods in Molecular Biology, 1091 pp. 95-121. | Show Abstract | Read more

This chapter describes the step-by-step methods employed by the Structural Genomics Consortium (SGC) for screening and producing proteins in the baculovirus expression vector system (BEVS). This eukaryotic expression system was selected and a screening process established in 2007 as a measure to tackle the more challenging kinase, RNA-DNA processing and integral membrane protein families on our target list. Here, we discuss our platform for identifying soluble proteins from 3 ml of insect cell culture and describe the procedures involved in producing protein from liter-scale cultures. Although not discussed in this chapter, the same process can also be applied to integral membrane proteins (IMPs) with slight adaptations to the purification procedure. © 2014 Springer Science+Business Media, LLC.

Burgess-Brown NA, Mahajan P, Strain-Damerell C, Gileadi O, Gräslund S. 2014. Medium-Throughput Production of Recombinant Human Proteins: Protein Production in E. coli Methods in Molecular Biology, 1091 pp. 73-94. | Show Abstract | Read more

In Chapter 4 we described the SGC process for generating multiple constructs of truncated versions of each protein using LIC. In this chapter we provide a step-by-step procedure of our E. coli system for test expressing intracellular (soluble) proteins in a 96-well format that enables us to identify which proteins or truncated versions are expressed in a soluble and stable form suitable for structural studies. In addition, we detail the process for scaling up cultures for large-scale protein purification. This level of production is required to obtain sufficient quantities (i.e., milligram amounts) of protein for further characterization and/or crystallization experiments. Our standard process is purification by immobilized metal affinity chromatography (IMAC) using nickel resin followed by size exclusion chromatography (SEC), with additional procedures arising from the complexity of the protein itself. © 2014 Springer Science+Business Media, LLC.

Strain-Damerell C, Mahajan P, Gileadi O, Burgess-Brown NA. 2014. Medium-Throughput Production of Recombinant Human Proteins: Ligation-Independent Cloning Methods in Molecular Biology, 1091 pp. 55-72. | Show Abstract | Read more

Structural genomics groups have identified the need to generate multiple truncated versions of each target to improve their success in producing a well-expressed, soluble, and stable protein and one that crystallizes and diffracts to a sufficient resolution for structural determination. At the SGC, we opted for the Ligation-Independent Cloning (LIC) method which provides the medium throughput we desire to produce and screen many proteins in a parallel process. Here, we describe our LIC protocol for generating constructs in a 96-well format and provide a choice of vectors suitable for expressing proteins in both E. coli and the baculovirus expression vector system (BEVS). © 2014 Springer Science+Business Media, LLC.

Mahajan P, Strain-Damerell C, Gileadi O, Burgess-Brown NA. 2014. Medium-throughput production of recombinant human proteins: protein production in insect cells. Methods Mol Biol, 1091 pp. 95-121. | Show Abstract | Read more

This chapter describes the step-by-step methods employed by the Structural Genomics Consortium (SGC) for screening and producing proteins in the baculovirus expression vector system (BEVS). This eukaryotic expression system was selected and a screening process established in 2007 as a measure to tackle the more challenging kinase, RNA-DNA processing and integral membrane protein families on our target list. Here, we discuss our platform for identifying soluble proteins from 3 ml of insect cell culture and describe the procedures involved in producing protein from liter-scale cultures. Although not discussed in this chapter, the same process can also be applied to integral membrane proteins (IMPs) with slight adaptations to the purification procedure.

Burgess-Brown NA, Mahajan P, Strain-Damerell C, Gileadi O, Gräslund S. 2014. Medium-throughput production of recombinant human proteins: protein production in E. coli. Methods Mol Biol, 1091 pp. 73-94. | Show Abstract | Read more

In Chapter 4 we described the SGC process for generating multiple constructs of truncated versions of each protein using LIC. In this chapter we provide a step-by-step procedure of our E. coli system for test expressing intracellular (soluble) proteins in a 96-well format that enables us to identify which proteins or truncated versions are expressed in a soluble and stable form suitable for structural studies. In addition, we detail the process for scaling up cultures for large-scale protein purification. This level of production is required to obtain sufficient quantities (i.e., milligram amounts) of protein for further characterization and/or crystallization experiments. Our standard process is purification by immobilized metal affinity chromatography (IMAC) using nickel resin followed by size exclusion chromatography (SEC), with additional procedures arising from the complexity of the protein itself.

Strain-Damerell C, Mahajan P, Gileadi O, Burgess-Brown NA. 2014. Medium-throughput production of recombinant human proteins: ligation-independent cloning. Methods Mol Biol, 1091 pp. 55-72. | Show Abstract | Read more

Structural genomics groups have identified the need to generate multiple truncated versions of each target to improve their success in producing a well-expressed, soluble, and stable protein and one that crystallizes and diffracts to a sufficient resolution for structural determination. At the SGC, we opted for the Ligation-Independent Cloning (LIC) method which provides the medium throughput we desire to produce and screen many proteins in a parallel process. Here, we describe our LIC protocol for generating constructs in a 96-well format and provide a choice of vectors suitable for expressing proteins in both E. coli and the baculovirus expression vector system (BEVS).

Nascimento AFZ, Trindade DM, Tonoli CCC, de Giuseppe PO, Assis LHP, Honorato RV, de Oliveira PSL, Mahajan P, Burgess-Brown NA, von Delft F et al. 2013. Structural insights into functional overlapping and differentiation among myosin V motors. J Biol Chem, 288 (47), pp. 34131-34145. | Show Abstract | Read more

Myosin V (MyoV) motors have been implicated in the intracellular transport of diverse cargoes including vesicles, organelles, RNA-protein complexes, and regulatory proteins. Here, we have solved the cargo-binding domain (CBD) structures of the three human MyoV paralogs (Va, Vb, and Vc), revealing subtle structural changes that drive functional differentiation and a novel redox mechanism controlling the CBD dimerization process, which is unique for the MyoVc subclass. Moreover, the cargo- and motor-binding sites were structurally assigned, indicating the conservation of residues involved in the recognition of adaptors for peroxisome transport and providing high resolution insights into motor domain inhibition by CBD. These results contribute to understanding the structural requirements for cargo transport, autoinhibition, and regulatory mechanisms in myosin V motors.

Shintre CA, Pike ACW, Li Q, Kim J-I, Barr AJ, Goubin S, Shrestha L, Yang J, Berridge G, Ross J et al. 2013. Structures of ABCB10, a human ATP-binding cassette transporter in apo- and nucleotide-bound states. Proc Natl Acad Sci U S A, 110 (24), pp. 9710-9715. | Show Abstract | Read more

ABCB10 is one of the three ATP-binding cassette (ABC) transporters found in the inner membrane of mitochondria. In mammals ABCB10 is essential for erythropoiesis, and for protection of mitochondria against oxidative stress. ABCB10 is therefore a potential therapeutic target for diseases in which increased mitochondrial reactive oxygen species production and oxidative stress play a major role. The crystal structure of apo-ABCB10 shows a classic exporter fold ABC transporter structure, in an open-inwards conformation, ready to bind the substrate or nucleotide from the inner mitochondrial matrix or membrane. Unexpectedly, however, ABCB10 adopts an open-inwards conformation when complexed with nonhydrolysable ATP analogs, in contrast to other transporter structures which adopt an open-outwards conformation in complex with ATP. The three complexes of ABCB10/ATP analogs reported here showed varying degrees of opening of the transport substrate binding site, indicating that in this conformation there is some flexibility between the two halves of the protein. These structures suggest that the observed plasticity, together with a portal between two helices in the transmembrane region of ABCB10, assist transport substrate entry into the substrate binding cavity. These structures indicate that ABC transporters may exist in an open-inwards conformation when nucleotide is bound. We discuss ways in which this observation can be aligned with the current views on mechanisms of ABC transporters.

Quigley A, Dong YY, Pike ACW, Dong L, Shrestha L, Berridge G, Stansfeld PJ, Sansom MSP, Edwards AM, Bountra C et al. 2013. The structural basis of ZMPSTE24-dependent laminopathies. Science, 339 (6127), pp. 1604-1607. | Show Abstract | Read more

Mutations in the nuclear membrane zinc metalloprotease ZMPSTE24 lead to diseases of lamin processing (laminopathies), such as the premature aging disease progeria and metabolic disorders. ZMPSTE24 processes prelamin A, a component of the nuclear lamina intermediate filaments, by cleaving it at two sites. Failure of this processing results in accumulation of farnesylated, membrane-associated prelamin A. The 3.4 angstrom crystal structure of human ZMPSTE24 has a seven transmembrane α-helical barrel structure, surrounding a large, water-filled, intramembrane chamber, capped by a zinc metalloprotease domain with the catalytic site facing into the chamber. The 3.8 angstrom structure of a complex with a CSIM tetrapeptide showed that the mode of binding of the substrate resembles that of an insect metalloprotease inhibitor in thermolysin. Laminopathy-associated mutations predicted to reduce ZMPSTE24 activity map to the zinc metalloprotease peptide-binding site and to the bottom of the chamber.

Cited:

45

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Quigley A, Dong YY, Pike ACW, Dong L, Shrestha L, Berridge G, Stansfeld PJ, Sansom MSP, Edwards AM, Bountra C et al. 2013. The structural basis of ZMPSTE24-dependent laminopathies Science, 340 (6127), pp. 1604-1607. | Show Abstract | Read more

Mutations in the nuclear membrane zinc metalloprotease ZMPSTE24 lead to diseases of lamin processing (laminopathies), such as the premature aging disease progeria and metabolic disorders. ZMPSTE24 processes prelamin A, a component of the nuclear lamina intermediate filaments, by cleaving it at two sites. Failure of this processing results in accumulation of farnesylated, membrane-associated prelamin A. The 3.4 angstrom crystal structure of human ZMPSTE24 has a seven transmembrane α-helical barrel structure, surrounding a large, water-filled, intramembrane chamber, capped by a zinc metalloprotease domain with the catalytic site facing into the chamber. The 3.8 angstrom structure of a complex with a CSIM tetrapeptide showed that the mode of binding of the substrate resembles that of an insect metalloprotease inhibitor in thermolysin. Laminopathy-associated mutations predicted to reduce ZMPSTE24 activity map to the zinc metalloprotease peptide - binding site and to the bottom of the chamber.

Cited:

37

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Watson AA, Mahajan P, Mertens HDT, Deery MJ, Zhang W, Pham P, Du X, Bartke T, Zhang W, Edlich C et al. 2012. The PHD and chromo domains regulate the atpase activity of the human chromatin remodeler CHD4 Journal of Molecular Biology, 422 (1), pp. 3-17. | Show Abstract | Read more

The NuRD (nucleosome remodeling and deacetylase) complex serves as a crucial epigenetic regulator of cell differentiation, proliferation, and hematopoietic development by coupling the deacetylation and demethylation of histones, nucleosome mobilization, and the recruitment of transcription factors. The core nucleosome remodeling function of the mammalian NuRD complex is executed by the helicase-domain-containing ATPase CHD4 (Mi-2β) subunit, which also contains N-terminal plant homeodomain (PHD) and chromo domains. The mode of regulation of chromatin remodeling by CHD4 is not well understood, nor is the role of its PHD and chromo domains. Here, we use small-angle X-ray scattering, nucleosome binding ATPase and remodeling assays, limited proteolysis, cross-linking, and tandem mass spectrometry to propose a three-dimensional structural model describing the overall shape and domain interactions of CHD4 and discuss the relevance of these for regulating the remodeling of chromatin by the NuRD complex. © 2012 Elsevier Ltd. All rights reserved.

Rose NR, Woon ECY, Tumber A, Walport LJ, Chowdhury R, Li XS, King ONF, Lejeune C, Ng SS, Krojer T et al. 2012. Plant growth regulator daminozide is a selective inhibitor of human KDM2/7 histone demethylases. J Med Chem, 55 (14), pp. 6639-6643. | Show Abstract | Read more

The JmjC oxygenases catalyze the N-demethylation of N(ε)-methyl lysine residues in histones and are current therapeutic targets. A set of human 2-oxoglutarate analogues were screened using a unified assay platform for JmjC demethylases and related oxygenases. Results led to the finding that daminozide (N-(dimethylamino)succinamic acid, 160 Da), a plant growth regulator, selectively inhibits the KDM2/7 JmjC subfamily. Kinetic and crystallographic studies reveal that daminozide chelates the active site metal via its hydrazide carbonyl and dimethylamino groups.

Keates T, Cooper CDO, Savitsky P, Allerston CK, Phillips C, Hammarström M, Daga N, Berridge G, Mahajan P, Burgess-Brown NA et al. 2012. Expressing the human proteome for affinity proteomics: Optimising expression of soluble protein domains and in vivo biotinylation New Biotechnology, 29 (5), pp. 515-525. | Show Abstract | Read more

The generation of affinity reagents to large numbers of human proteins depends on the ability to express the target proteins as high-quality antigens. The Structural Genomics Consortium (SGC) focuses on the production and structure determination of human proteins. In a 7-year period, the SGC has deposited crystal structures of >800 human protein domains, and has additionally expressed and purified a similar number of protein domains that have not yet been crystallised. The targets include a diversity of protein domains, with an attempt to provide high coverage of protein families. The family approach provides an excellent basis for characterising the selectivity of affinity reagents. We present a summary of the approaches used to generate purified human proteins or protein domains, a test case demonstrating the ability to rapidly generate new proteins, and an optimisation study on the modification of >70 proteins by biotinylation in vivo. These results provide a unique synergy between large-scale structural projects and the recent efforts to produce a wide coverage of affinity reagents to the human proteome. © 2011 Elsevier B.V.

Watson AA, Mahajan P, Mertens HDT, Deery MJ, Zhang W, Pham P, Du X, Bartke T, Zhang W, Edlich C et al. 2012. The PHD and chromo domains regulate the ATPase activity of the human chromatin remodeler CHD4. J Mol Biol, 422 (1), pp. 3-17. | Show Abstract | Read more

The NuRD (nucleosome remodeling and deacetylase) complex serves as a crucial epigenetic regulator of cell differentiation, proliferation, and hematopoietic development by coupling the deacetylation and demethylation of histones, nucleosome mobilization, and the recruitment of transcription factors. The core nucleosome remodeling function of the mammalian NuRD complex is executed by the helicase-domain-containing ATPase CHD4 (Mi-2β) subunit, which also contains N-terminal plant homeodomain (PHD) and chromo domains. The mode of regulation of chromatin remodeling by CHD4 is not well understood, nor is the role of its PHD and chromo domains. Here, we use small-angle X-ray scattering, nucleosome binding ATPase and remodeling assays, limited proteolysis, cross-linking, and tandem mass spectrometry to propose a three-dimensional structural model describing the overall shape and domain interactions of CHD4 and discuss the relevance of these for regulating the remodeling of chromatin by the NuRD complex.

Keates T, Cooper CDO, Savitsky P, Allerston CK, Phillips C, Hammarström M, Daga N, Berridge G, Mahajan P, Burgess-Brown NA et al. 2012. Expressing the human proteome for affinity proteomics: optimising expression of soluble protein domains and in vivo biotinylation. N Biotechnol, 29 (5), pp. 515-525. | Show Abstract | Read more

The generation of affinity reagents to large numbers of human proteins depends on the ability to express the target proteins as high-quality antigens. The Structural Genomics Consortium (SGC) focuses on the production and structure determination of human proteins. In a 7-year period, the SGC has deposited crystal structures of >800 human protein domains, and has additionally expressed and purified a similar number of protein domains that have not yet been crystallised. The targets include a diversity of protein domains, with an attempt to provide high coverage of protein families. The family approach provides an excellent basis for characterising the selectivity of affinity reagents. We present a summary of the approaches used to generate purified human proteins or protein domains, a test case demonstrating the ability to rapidly generate new proteins, and an optimisation study on the modification of >70 proteins by biotinylation in vivo. These results provide a unique synergy between large-scale structural projects and the recent efforts to produce a wide coverage of affinity reagents to the human proteome.

Wang AT, Sengerová B, Cattell E, Inagawa T, Hartley JM, Kiakos K, Burgess-Brown NA, Swift LP, Enzlin JH, Schofield CJ et al. 2011. Human SNM1A and XPF-ERCC1 collaborate to initiate DNA interstrand cross-link repair. Genes Dev, 25 (17), pp. 1859-1870. | Show Abstract | Read more

One of the major DNA interstrand cross-link (ICL) repair pathways in mammalian cells is coupled to replication, but the mechanistic roles of the critical factors involved remain largely elusive. Here, we show that purified human SNM1A (hSNM1A), which exhibits a 5'-3' exonuclease activity, can load from a single DNA nick and digest past an ICL on its substrate strand. hSNM1A-depleted cells are ICL-sensitive and accumulate replication-associated DNA double-strand breaks (DSBs), akin to ERCC1-depleted cells. These DSBs are Mus81-induced, indicating that replication fork cleavage by Mus81 results from the failure of the hSNM1A- and XPF-ERCC1-dependent ICL repair pathway. Our results reveal how collaboration between hSNM1A and XPF-ERCC1 is necessary to initiate ICL repair in replicating human cells.

Cited:

74

Scopus

Wang AT, Sengerová B, Cattell E, Inagawa T, Hartley JM, Kiakos K, Burgess-Brown NA, Swift LP, Enzlin JH, Schofield CJ et al. 2011. Human SNM1a and XPF-ERCC1 collaborate to initiate DNA interstrand cross-link repair Genes and Development, 25 (17), pp. 1859-1870. | Show Abstract | Read more

One of the major DNA interstrand cross-link (ICL) repair pathways in mammalian cells is coupled to replication, but the mechanistic roles of the critical factors involved remain largely elusive. Here, we show that purified human SNM1A (hSNM1A), which exhibits a 59-39 exonuclease activity, can load from a single DNA nick and digest past an ICL on its substrate strand. hSNM1A-depleted cells are ICL-sensitive and accumulate replicationassociated DNA double-strand breaks (DSBs), akin to ERCC1-depleted cells. These DSBs are Mus81-induced, indicating that replication fork cleavage by Mus81 results from the failure of the hSNM1A- and XPF-ERCC1-dependent ICL repair pathway. Our results reveal how collaboration between hSNM1A and XPF-ERCC1 is necessary to initiate ICL repair in replicating human cells. © 2011 by Cold Spring Harbor Laboratory Press.

Berridge G, Chalk R, D'Avanzo N, Dong L, Doyle D, Kim JI, Xia X, Burgess-Brown N, Deriso A, Carpenter EP, Gileadi O. 2011. High-performance liquid chromatography separation and intact mass analysis of detergent-solubilized integral membrane proteins Analytical Biochemistry, 410 (2), pp. 272-280. | Show Abstract | Read more

We have developed a method for intact mass analysis of detergent- solubilized and purified integral membrane proteins using liquid chromatography-mass spectrometry (LC-MS) with methanol as the organic mobile phase. Membrane proteins and detergents are separated chromatographically during the isocratic stage of the gradient profile from a 150-mm C3 reversed-phase column. The mass accuracy is comparable to standard methods employed for soluble proteins; the sensitivity is 10-fold lower, requiring 0.2-5 μg of protein. The method is also compatible with our standard LC-MS method used for intact mass analysis of soluble proteins and may therefore be applied on a multiuser instrument or in a high-throughput environment. © 2010 Elsevier Inc. All rights reserved.

Berridge G, Chalk R, D'Avanzo N, Dong L, Doyle D, Kim J-I, Xia X, Burgess-Brown N, Deriso A, Carpenter EP, Gileadi O. 2011. High-performance liquid chromatography separation and intact mass analysis of detergent-solubilized integral membrane proteins. Anal Biochem, 410 (2), pp. 272-280. | Show Abstract | Read more

We have developed a method for intact mass analysis of detergent-solubilized and purified integral membrane proteins using liquid chromatography-mass spectrometry (LC-MS) with methanol as the organic mobile phase. Membrane proteins and detergents are separated chromatographically during the isocratic stage of the gradient profile from a 150-mm C3 reversed-phase column. The mass accuracy is comparable to standard methods employed for soluble proteins; the sensitivity is 10-fold lower, requiring 0.2-5 μg of protein. The method is also compatible with our standard LC-MS method used for intact mass analysis of soluble proteins and may therefore be applied on a multiuser instrument or in a high-throughput environment.

Lucic B, Zhang Y, King O, Mendoza-Maldonado R, Berti M, Niesen FH, Burgess-Brown NA, Pike ACW, Cooper CDO, Gileadi O, Vindigni A. 2011. A prominent β-hairpin structure in the winged-helix domain of RECQ1 is required for DNA unwinding and oligomer formation. Nucleic Acids Res, 39 (5), pp. 1703-1717. | Show Abstract | Read more

RecQ helicases have attracted considerable interest in recent years due to their role in the suppression of genome instability and human diseases. These atypical helicases exert their function by resolving a number of highly specific DNA structures. The crystal structure of a truncated catalytic core of the human RECQ1 helicase (RECQ1(49-616)) shows a prominent β-hairpin, with an aromatic residue (Y564) at the tip, located in the C-terminal winged-helix domain. Here, we show that the β-hairpin is required for the DNA unwinding and Holliday junction (HJ) resolution activity of full-length RECQ1, confirming that it represents an important determinant for the distinct substrate specificity of the five human RecQ helicases. In addition, we found that the β-hairpin is required for dimer formation in RECQ1(49-616) and tetramer formation in full-length RECQ1. We confirmed the presence of stable RECQ1(49-616) dimers in solution and demonstrated that dimer formation favours DNA unwinding; even though RECQ1 monomers are still active. Tetramers are instead necessary for more specialized activities such as HJ resolution and strand annealing. Interestingly, two independent protein-protein contacts are required for tetramer formation, one involves the β-hairpin and the other the N-terminus of RECQ1, suggesting a non-hierarchical mechanism of tetramer assembly.

Savitsky P, Bray J, Cooper CDO, Marsden BD, Mahajan P, Burgess-Brown NA, Gileadi O. 2010. High-throughput production of human proteins for crystallization: the SGC experience. J Struct Biol, 172 (1), pp. 3-13. | Show Abstract | Read more

Producing purified human proteins with high yield and purity remains a considerable challenge. We describe the methods utilized in the Structural Genomics Consortium (SGC) in Oxford, resulting in successful purification of 48% of human proteins attempted; of those, the structures of approximately 40% were solved by X-ray crystallography. The main driver has been the parallel processing of multiple (typically 9-20) truncated constructs of each target; modest diversity in vectors and host systems; and standardized purification procedures. We provide method details as well as data on the properties of the constructs leading to crystallized proteins and the impact of methodological variants. These can be used to formulate guidelines for initial approaches to expression of new eukaryotic proteins.

Pike ACW, Shrestha B, Popuri V, Burgess-Brown N, Muzzolini L, Costantini S, Vindigni A, Gileadi O. 2009. Structure of the human RECQ1 helicase reveals a putative strand-separation pin. Proc Natl Acad Sci U S A, 106 (4), pp. 1039-1044. | Show Abstract | Read more

RecQ-like helicases, which include 5 members in the human genome, are important in maintaining genome integrity. We present a crystal structure of a truncated form of the human RECQ1 protein with Mg-ADP. The truncated protein is active in DNA fork unwinding but lacks other activities of the full-length enzyme: disruption of Holliday junctions and DNA strand annealing. The structure of human RECQ1 resembles that of Escherichia coli RecQ, with some important differences. All structural domains are conserved, including the 2 RecA-like domains and the RecQ-specific zinc-binding and winged-helix (WH) domains. However, the WH domain is positioned at a different orientation from that of the E. coli enzyme. We identify a prominent beta-hairpin of the WH domain as essential for DNA strand separation, which may be analogous to DNA strand-separation features of other DNA helicases. This hairpin is significantly shorter in the E. coli enzyme and is not required for its helicase activity, suggesting that there are significant differences between the modes of action of RecQ family members.

Barr AJ, Ugochukwu E, Lee WH, King ONF, Filippakopoulos P, Alfano I, Savitsky P, Burgess-Brown NA, Müller S, Knapp S. 2009. Large-scale structural analysis of the classical human protein tyrosine phosphatome. Cell, 136 (2), pp. 352-363. | Show Abstract | Read more

Protein tyrosine phosphatases (PTPs) play a critical role in regulating cellular functions by selectively dephosphorylating their substrates. Here we present 22 human PTP crystal structures that, together with prior structural knowledge, enable a comprehensive analysis of the classical PTP family. Despite their largely conserved fold, surface properties of PTPs are strikingly diverse. A potential secondary substrate-binding pocket is frequently found in phosphatases, and this has implications for both substrate recognition and development of selective inhibitors. Structural comparison identified four diverse catalytic loop (WPD) conformations and suggested a mechanism for loop closure. Enzymatic assays revealed vast differences in PTP catalytic activity and identified PTPD1, PTPD2, and HDPTP as catalytically inert protein phosphatases. We propose a "head-to-toe" dimerization model for RPTPgamma/zeta that is distinct from the "inhibitory wedge" model and that provides a molecular basis for inhibitory regulation. This phosphatome resource gives an expanded insight into intrafamily PTP diversity, catalytic activity, substrate recognition, and autoregulatory self-association.

Burgess-Brown NA, Sharma S, Sobott F, Loenarz C, Oppermann U, Gileadi O. 2008. Codon optimization can improve expression of human genes in Escherichia coli: A multi-gene study. Protein Expr Purif, 59 (1), pp. 94-102. | Show Abstract | Read more

The efficiency of heterologous protein production in Escherichia coli (E. coli) can be diminished by biased codon usage. Approaches normally used to overcome this problem include targeted mutagenesis to remove rare codons or the addition of rare codon tRNAs in specific cell lines. Recently, improvements in technology have enabled cost-effective production of synthetic genes, making this a feasible alternative. To explore this option, the expression patterns in E. coli of 30 human short-chain dehydrogenase/reductase genes (SDRs) were analyzed in three independent experiments, comparing the native and synthetic (codon-optimized) versions of each gene. The constructs were prepared in a pET-derived vector that appends an N-terminal polyhistidine tag to the protein; expression was induced using IPTG and soluble proteins were isolated by Ni-NTA metal-affinity chromatography. Expression of the native and synthetic gene constructs was compared in two isogenic bacterial strains, one of which contained a plasmid (pRARE2) that carries seven tRNAs recognizing rare codons. Although we found some degree of variability between experiments, in normal E. coli synthetic genes could be expressed and purified more readily than the native version. In only one case was native gene expression better. Importantly, in most but not all cases, expression of the native genes in combination with rare codon tRNAs mimicked the behavior of the synthetic genes in the native strain. The trend is that heterologous expression of some proteins in bacteria can be improved by altering codon preference, but that this effect can be generally recapitulated by introducing rare codon tRNAs into the host cell.

Gileadi O, Burgess-Brown NA, Colebrook SM, Berridge G, Savitsky P, Smee CEA, Loppnau P, Johansson C, Salah E, Pantic NH. 2008. High throughput production of recombinant human proteins for crystallography. Methods Mol Biol, 426 pp. 221-246. | Show Abstract | Read more

This chapter presents in detail the process used in high throughput bacterial production of recombinant human proteins for crystal structure determination. The core principles are: (1) Generating at least 10 truncated constructs from each target gene. (2) Ligation-independent cloning (LIC) into a bacterial expression vector. All proteins are expressed with an N-terminal, TEV protease cleavable fusion peptide. (3) Small-scale test expression to identify constructs producing soluble protein. (4) Liter-scale production in shaker flasks. (5) Purification by Ni-affinity chromatography and gel filtration. (6) Protein characterization and preparation for crystallography. The chapter also briefly presents alternative procedures, to be applied based on specific knowledge of protein families or when the core protocol is unsatisfactory. This scheme has been applied to more than 550 human proteins (>10,000 constructs) and has resulted in the deposition of 112 unique structures. The methods presented do not depend on specialized equipment or robotics; hence, they provide an effective approach for handling individual proteins in a regular research lab.

Boyd RS, Adam PJ, Patel S, Loader JA, Berry J, Redpath NT, Poyser HR, Fletcher GC, Burgess NA, Stamps AC et al. 2003. Proteomic analysis of the cell-surface membrane in chronic lymphocytic leukemia: identification of two novel proteins, BCNP1 and MIG2B. Leukemia, 17 (8), pp. 1605-1612. | Show Abstract | Read more

B-cell-specific plasma-membrane proteins are potential targets for either small molecule or antibody-based therapies. We have sought to annotate proteins expressed at the cell surface membrane in patients with chronic lymphocytic leukemia (CLL) using plasma-membrane-based proteomic analysis to identify previously uncharacterized and potentially B-cell-specific proteins. Proteins from plasma-membrane fractions were separated on one-dimensional gels and trypsinized fractions subjected to high-throughput MALDI-TOF mass spectrometry. Using this method, many known B-cell surface antigens were detected, but also known proteins not previously described in this disease or in this cellular compartment, including cell surface receptors, membrane-associated enzymes and secreted proteins, and completely unknown proteins. To validate the method, we show that BLK, a B-cell-specific kinase, is located in the CLL-plasma-membrane fraction. We also describe two novel proteins (MIG2B and B-cell novel protein #1, BCNP1), which are expressed preferentially in B cells. MIG2B is in a highly conserved and defined gene family containing two plasma-membrane-binding ezrin/radixin/moesin domains and a pleckstrin homology domain; the Caenorhabditis elegans homolog (UNC-112) is a membrane-associated protein that colocalizes with integrin at cell-matrix adhesion complexes. BCNP1 is a completely unknown protein with three predicted transmembrane domains, with three alternatively spliced final exons. Proteomic analysis may thus define new potential therapeutic targets.

Winzer K, Hardie KR, Burgess N, Doherty N, Kirke D, Holden MTG, Linforth R, Cornell KA, Taylor AJ, Hill PJ, Williams P. 2002. LuxS: its role in central metabolism and the in vitro synthesis of 4-hydroxy-5-methyl-3(2H)-furanone. Microbiology, 148 (Pt 4), pp. 909-922. | Show Abstract | Read more

Many bacteria produce extracellular molecules which function in cell-to-cell communication. One of these molecules, autoinducer 2 (AI-2), was first described as an extracellular signal produced by Vibrio harveyi to control luciferase expression. Subsequently, a number of bacteria have been shown to possess AI-2 activity in their culture supernatants, and bear the luxS gene product, which is required for AI-2 synthesis. In Porphyromonas gingivalis, luxS and pfs, encoding a 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTA/SAH'ase), form an operon, suggesting that S-adenosylhomocysteine (SAH) or 5'-methylthioadenosine (MTA) serves as a substrate for AI-2 production. Cell-free extracts of Escherichia coli MG1655, but not DH5alpha (which carries a luxS frame-shift mutation) were capable of generating AI-2 activity upon addition of SAH, but not MTA. S-Ribosyl-homocysteine (RH) derived from SAH also served as a substrate in E. coli MG1655 extracts. RH-supplemented cell-free extracts of Pseudomonas aeruginosa, a bacterium that lacks luxS, only generated AI-2 activity following the introduction of a plasmid containing the Por. gingivalis pfs-luxS operon. In addition, defined in vitro systems consisting of the purified LuxS proteins from Por. gingivalis, E. coli, Neisseria meningitidis or Staphylococcus aureus converted RH to homocysteine and a compound that exhibits AI-2 activity.4-Hydroxy-5-methyl-3(2H)-furanone was identified by mass spectrometry analysis as a major product formed in this in vitro reaction. In E. coli MG1655, expression of T3SH [the bacteriophage T3 S-adenosylmethionine (SAM) hydrolase] significantly reduced AI-2 activity in culture supernatants, suggesting that AI-2 production is limited by the amount of SAH produced in SAM-dependent transmethylase reactions. The authors suggest that the LuxS protein has an important metabolic function in the recycling of SAH. They also show that Ps. aeruginosa is capable of removing AI-2 activity, implying that this molecule may act as a nutrient. In many bacteria AI-2 may in fact represent not a signal molecule but a metabolite which is released early and metabolized in the later stages of growth.

Burgess NA, Kirke DF, Williams P, Winzer K, Hardie KR, Meyers NL, Aduse-Opoku J, Curtis MA, Cámara M. 2002. LuxS-dependent quorum sensing in Porphyromonas gingivalis modulates protease and haemagglutinin activities but is not essential for virulence. Microbiology, 148 (Pt 3), pp. 763-772. | Show Abstract | Read more

Porphyromonas gingivalis is a Gram-negative black-pigmented obligate anaerobe implicated in the aetiology of human periodontal disease. The virulence of P. gingivalis is associated with the elaboration of the cysteine proteases Arg-gingipain (Rgp) and Lys-gingipain (Kgp), which are produced at high bacterial cell densities. To determine whether quorum sensing plays a role in the regulation of Rgp and Kgp, biosensors capable of detecting either N-acylhomoserine lactone (AHLs) or the luxS-dependent autoinducer (AI-2) quorum-sensing signalling molecules in spent culture supernatants were first employed. While no AHLs could be detected, the Vibrio harveyi BB170 biosensor was activated by spent P. gingivalis W50 culture supernatants. The P. gingivalis luxS gene was cloned and demonstrated to restore AI-2 production in the Escherichia coli luxS mutant DH5alpha. Mutation of luxS abolished AI-2 production in P. gingivalis. Western blotting using antibodies raised against the recombinant protein revealed that LuxS levels increased throughout growth even though AI-2 activity was only maximally detected at the mid-exponential phase of growth and disappeared by the onset of stationary phase. Similar results were obtained with E. coli DH5alpha transformed with luxS, suggesting that AI-2 production is not limited by a lack of LuxS protein. Analysis of Rgp and Kgp protease activities revealed that the P. gingivalis luxS mutant produced around 45% less Rgp and 30% less Kgp activity than the parent strain. In addition, the luxS mutant exhibited a fourfold reduction in haemagglutinin titre. However, these reductions in virulence determinant levels were insufficient to attenuate the luxS mutant in a murine lesion model of P. gingivalis infection.

Cited:

85

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Burgess NA, Aduse-Opoku J, Cámara M, Winzer K, Williams P, Meyers NL, Curtis MA, Kirke DF, Hardie KR. 2002. LuxS-dependent quorum sensing in Porphyromonas gingivalis modulates protease and haemagglutinin activities but is not essential for virulence Microbiology, 148 (3), pp. 763-772. | Show Abstract | Read more

Porphyromonas gingivalis is a Gram-negative black-pigmented obligate anaerobe implicated in the aetiology of human periodontal disease. The virulence of P. gingivalis is associated with the elaboration of the cysteine proteases Arg-gingipain (Rgp) and Lys-gingipain (Kgp), which are produced at high bacterial cell densities. To determine whether quorum sensing plays a role in the regulation of Rgp and Kgp, biosensors capable of detecting either N-acylhomoserine lactone (AHLs) or the luxS-dependent autoinducer (AI-2) quorum-sensing signalling molecules in spent culture supernatants were first employed. While no AHLs could be detected, the Vibrio harveyi BB170 biosensor was activated by spent P. gingivalis W50 culture supernatants. The P. gingivalis luxS gene was cloned and demonstrated to restore AI-2 production in the Escherichia coli luxS mutant DH5α. Mutation of luxS abolished AI-2 production in P. gingivalis. Western blotting using antibodies raised against the recombinant protein revealed that LuxS levels increased throughout growth even though AI-2 activity was only maximally detected at the mid-exponential phase of growth and disappeared by the onset of stationary phase. Similar results were obtained with E. coli DH5α transformed with luxS, suggesting that AI-2 production is not limited by a lack of LuxS protein. Analysis of Rgp and Kgp protease activities revealed that the P. gingivalis luxS mutant produced around 45% less Rgp and 30% less Kgp activity than the parent strain. In addition, the luxS mutant exhibited a fourfold reduction in haemagglutinin titre. However, these reductions in virulence determinant levels were insufficient to attenuate the luxS mutant in a murine lesion model of P. gingivalis infection.

Cited:

237

Scopus

Doherty N, Cornell KA, Burgess N, Linforth R, Williams P, Hill PJ, Taylor AJ, Hardie KR, Winzer K, Holden MTG, Kirke D. 2002. LuxS: its role in central metabolism and the in vitro synthesis of 4-hydroxy-5-methyl-3(2H)-furanone Microbiology, 148 (4), pp. 909-922. | Show Abstract | Read more

Many bacteria produce extracellular molecules which function in cell-to-cell communication. One of these molecules, autoinducer 2 (Al-2), was first described as an extracellular signal produced by Vibrio harveyi to control luciferase expression. Subsequently, a number of bacteria have been shown to possess Al-2 activity in their culture supernatants, and bear the luxS gene product, which is required for Al-2 synthesis. In Porphyromonas gingivalis, luxS and pfs, encoding a 5′-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTA/SAH'ase), form an operon, suggesting that S-adenosylhomocysteine (SAH) or 5′-methylthioadenosine (MTA) serves as a substrate for Al-2 production. Cell-free extracts of Escherichia coli MG1655, but not DH5α (which carries a luxS frame-shift mutation) were capable of generating Al-2 activity upon addition of SAH, but not MTA. S-Ribosylhomocysteine (RH) derived from SAH also served as a substrate in E. coli MG1655 extracts. RH-supplemented cell-free extracts of Pseudomonas aeruginosa, a bacterium that lacks luxS, only generated Al-2 activity following the introduction of a plasmid containing the Por. gingivalis pfs-luxS operon. In addition, defined in vitro systems consisting of the purified LuxS proteins from Por. gingivalis, E. coli, Neisseria meningitidis or Staphylococcus aureus converted RH to homocysteine and a compound that exhibits Al-2 activity. 4-Hydroxy-5-methyl-3(2H)-furanone was identified by mass spectrometry analysis as a major product formed in this in vitro reaction. In E. coli MG1655, expression of T3SH [the bacteriophage T3 S-adenosylmethionine (SAM) hydrolase] significantly reduced Al-2 activity in culture supernatants, suggesting that Al-2 production is limited by the amount of SAH produced in SAM-dependent transmethylase reactions. The authors suggest that the LuxS protein has an important metabolic function in the recycling of SAH. They also show that Ps. aeruginosa is capable of removing Al-2 activity, implying that this molecule may act as a nutrient. In many bacteria Al-2 may in fact represent not a signal molecule but a metabolite which is released early and metabolized in the later stages of growth.

Dong YY, Pike ACW, Mackenzie A, McClenaghan C, Aryal P, Dong L, Quigley A, Grieben M, Goubin S, Mukhopadhyay S et al. 2015. K2P channel gating mechanisms revealed by structures of TREK-2 and a complex with Prozac. Science, 347 (6227), pp. 1256-1259. | Show Abstract | Read more

TREK-2 (KCNK10/K2P10), a two-pore domain potassium (K2P) channel, is gated by multiple stimuli such as stretch, fatty acids, and pH and by several drugs. However, the mechanisms that control channel gating are unclear. Here we present crystal structures of the human TREK-2 channel (up to 3.4 angstrom resolution) in two conformations and in complex with norfluoxetine, the active metabolite of fluoxetine (Prozac) and a state-dependent blocker of TREK channels. Norfluoxetine binds within intramembrane fenestrations found in only one of these two conformations. Channel activation by arachidonic acid and mechanical stretch involves conversion between these states through movement of the pore-lining helices. These results provide an explanation for TREK channel mechanosensitivity, regulation by diverse stimuli, and possible off-target effects of the serotonin reuptake inhibitor Prozac.

Mahajan P, Strain-Damerell C, Gileadi O, Burgess-Brown NA. 2014. Medium-throughput production of recombinant human proteins: protein production in insect cells. Methods Mol Biol, 1091 pp. 95-121. | Show Abstract | Read more

This chapter describes the step-by-step methods employed by the Structural Genomics Consortium (SGC) for screening and producing proteins in the baculovirus expression vector system (BEVS). This eukaryotic expression system was selected and a screening process established in 2007 as a measure to tackle the more challenging kinase, RNA-DNA processing and integral membrane protein families on our target list. Here, we discuss our platform for identifying soluble proteins from 3 ml of insect cell culture and describe the procedures involved in producing protein from liter-scale cultures. Although not discussed in this chapter, the same process can also be applied to integral membrane proteins (IMPs) with slight adaptations to the purification procedure.

Burgess-Brown NA, Mahajan P, Strain-Damerell C, Gileadi O, Gräslund S. 2014. Medium-throughput production of recombinant human proteins: protein production in E. coli. Methods Mol Biol, 1091 pp. 73-94. | Show Abstract | Read more

In Chapter 4 we described the SGC process for generating multiple constructs of truncated versions of each protein using LIC. In this chapter we provide a step-by-step procedure of our E. coli system for test expressing intracellular (soluble) proteins in a 96-well format that enables us to identify which proteins or truncated versions are expressed in a soluble and stable form suitable for structural studies. In addition, we detail the process for scaling up cultures for large-scale protein purification. This level of production is required to obtain sufficient quantities (i.e., milligram amounts) of protein for further characterization and/or crystallization experiments. Our standard process is purification by immobilized metal affinity chromatography (IMAC) using nickel resin followed by size exclusion chromatography (SEC), with additional procedures arising from the complexity of the protein itself.

Strain-Damerell C, Mahajan P, Gileadi O, Burgess-Brown NA. 2014. Medium-throughput production of recombinant human proteins: ligation-independent cloning. Methods Mol Biol, 1091 pp. 55-72. | Show Abstract | Read more

Structural genomics groups have identified the need to generate multiple truncated versions of each target to improve their success in producing a well-expressed, soluble, and stable protein and one that crystallizes and diffracts to a sufficient resolution for structural determination. At the SGC, we opted for the Ligation-Independent Cloning (LIC) method which provides the medium throughput we desire to produce and screen many proteins in a parallel process. Here, we describe our LIC protocol for generating constructs in a 96-well format and provide a choice of vectors suitable for expressing proteins in both E. coli and the baculovirus expression vector system (BEVS).

Quigley A, Dong YY, Pike ACW, Dong L, Shrestha L, Berridge G, Stansfeld PJ, Sansom MSP, Edwards AM, Bountra C et al. 2013. The structural basis of ZMPSTE24-dependent laminopathies. Science, 339 (6127), pp. 1604-1607. | Show Abstract | Read more

Mutations in the nuclear membrane zinc metalloprotease ZMPSTE24 lead to diseases of lamin processing (laminopathies), such as the premature aging disease progeria and metabolic disorders. ZMPSTE24 processes prelamin A, a component of the nuclear lamina intermediate filaments, by cleaving it at two sites. Failure of this processing results in accumulation of farnesylated, membrane-associated prelamin A. The 3.4 angstrom crystal structure of human ZMPSTE24 has a seven transmembrane α-helical barrel structure, surrounding a large, water-filled, intramembrane chamber, capped by a zinc metalloprotease domain with the catalytic site facing into the chamber. The 3.8 angstrom structure of a complex with a CSIM tetrapeptide showed that the mode of binding of the substrate resembles that of an insect metalloprotease inhibitor in thermolysin. Laminopathy-associated mutations predicted to reduce ZMPSTE24 activity map to the zinc metalloprotease peptide-binding site and to the bottom of the chamber.

Rose NR, Woon ECY, Tumber A, Walport LJ, Chowdhury R, Li XS, King ONF, Lejeune C, Ng SS, Krojer T et al. 2012. Plant growth regulator daminozide is a selective inhibitor of human KDM2/7 histone demethylases. J Med Chem, 55 (14), pp. 6639-6643. | Show Abstract | Read more

The JmjC oxygenases catalyze the N-demethylation of N(ε)-methyl lysine residues in histones and are current therapeutic targets. A set of human 2-oxoglutarate analogues were screened using a unified assay platform for JmjC demethylases and related oxygenases. Results led to the finding that daminozide (N-(dimethylamino)succinamic acid, 160 Da), a plant growth regulator, selectively inhibits the KDM2/7 JmjC subfamily. Kinetic and crystallographic studies reveal that daminozide chelates the active site metal via its hydrazide carbonyl and dimethylamino groups.

Keates T, Cooper CDO, Savitsky P, Allerston CK, Phillips C, Hammarström M, Daga N, Berridge G, Mahajan P, Burgess-Brown NA et al. 2012. Expressing the human proteome for affinity proteomics: Optimising expression of soluble protein domains and in vivo biotinylation New Biotechnology, 29 (5), pp. 515-525. | Show Abstract | Read more

The generation of affinity reagents to large numbers of human proteins depends on the ability to express the target proteins as high-quality antigens. The Structural Genomics Consortium (SGC) focuses on the production and structure determination of human proteins. In a 7-year period, the SGC has deposited crystal structures of >800 human protein domains, and has additionally expressed and purified a similar number of protein domains that have not yet been crystallised. The targets include a diversity of protein domains, with an attempt to provide high coverage of protein families. The family approach provides an excellent basis for characterising the selectivity of affinity reagents. We present a summary of the approaches used to generate purified human proteins or protein domains, a test case demonstrating the ability to rapidly generate new proteins, and an optimisation study on the modification of >70 proteins by biotinylation in vivo. These results provide a unique synergy between large-scale structural projects and the recent efforts to produce a wide coverage of affinity reagents to the human proteome. © 2011 Elsevier B.V.

Wang AT, Sengerová B, Cattell E, Inagawa T, Hartley JM, Kiakos K, Burgess-Brown NA, Swift LP, Enzlin JH, Schofield CJ et al. 2011. Human SNM1A and XPF-ERCC1 collaborate to initiate DNA interstrand cross-link repair. Genes Dev, 25 (17), pp. 1859-1870. | Show Abstract | Read more

One of the major DNA interstrand cross-link (ICL) repair pathways in mammalian cells is coupled to replication, but the mechanistic roles of the critical factors involved remain largely elusive. Here, we show that purified human SNM1A (hSNM1A), which exhibits a 5'-3' exonuclease activity, can load from a single DNA nick and digest past an ICL on its substrate strand. hSNM1A-depleted cells are ICL-sensitive and accumulate replication-associated DNA double-strand breaks (DSBs), akin to ERCC1-depleted cells. These DSBs are Mus81-induced, indicating that replication fork cleavage by Mus81 results from the failure of the hSNM1A- and XPF-ERCC1-dependent ICL repair pathway. Our results reveal how collaboration between hSNM1A and XPF-ERCC1 is necessary to initiate ICL repair in replicating human cells.

Berridge G, Chalk R, D'Avanzo N, Dong L, Doyle D, Kim JI, Xia X, Burgess-Brown N, Deriso A, Carpenter EP, Gileadi O. 2011. High-performance liquid chromatography separation and intact mass analysis of detergent-solubilized integral membrane proteins Analytical Biochemistry, 410 (2), pp. 272-280. | Show Abstract | Read more

We have developed a method for intact mass analysis of detergent- solubilized and purified integral membrane proteins using liquid chromatography-mass spectrometry (LC-MS) with methanol as the organic mobile phase. Membrane proteins and detergents are separated chromatographically during the isocratic stage of the gradient profile from a 150-mm C3 reversed-phase column. The mass accuracy is comparable to standard methods employed for soluble proteins; the sensitivity is 10-fold lower, requiring 0.2-5 μg of protein. The method is also compatible with our standard LC-MS method used for intact mass analysis of soluble proteins and may therefore be applied on a multiuser instrument or in a high-throughput environment. © 2010 Elsevier Inc. All rights reserved.

Lucic B, Zhang Y, King O, Mendoza-Maldonado R, Berti M, Niesen FH, Burgess-Brown NA, Pike ACW, Cooper CDO, Gileadi O, Vindigni A. 2011. A prominent β-hairpin structure in the winged-helix domain of RECQ1 is required for DNA unwinding and oligomer formation. Nucleic Acids Res, 39 (5), pp. 1703-1717. | Show Abstract | Read more

RecQ helicases have attracted considerable interest in recent years due to their role in the suppression of genome instability and human diseases. These atypical helicases exert their function by resolving a number of highly specific DNA structures. The crystal structure of a truncated catalytic core of the human RECQ1 helicase (RECQ1(49-616)) shows a prominent β-hairpin, with an aromatic residue (Y564) at the tip, located in the C-terminal winged-helix domain. Here, we show that the β-hairpin is required for the DNA unwinding and Holliday junction (HJ) resolution activity of full-length RECQ1, confirming that it represents an important determinant for the distinct substrate specificity of the five human RecQ helicases. In addition, we found that the β-hairpin is required for dimer formation in RECQ1(49-616) and tetramer formation in full-length RECQ1. We confirmed the presence of stable RECQ1(49-616) dimers in solution and demonstrated that dimer formation favours DNA unwinding; even though RECQ1 monomers are still active. Tetramers are instead necessary for more specialized activities such as HJ resolution and strand annealing. Interestingly, two independent protein-protein contacts are required for tetramer formation, one involves the β-hairpin and the other the N-terminus of RECQ1, suggesting a non-hierarchical mechanism of tetramer assembly.

Savitsky P, Bray J, Cooper CDO, Marsden BD, Mahajan P, Burgess-Brown NA, Gileadi O. 2010. High-throughput production of human proteins for crystallization: the SGC experience. J Struct Biol, 172 (1), pp. 3-13. | Show Abstract | Read more

Producing purified human proteins with high yield and purity remains a considerable challenge. We describe the methods utilized in the Structural Genomics Consortium (SGC) in Oxford, resulting in successful purification of 48% of human proteins attempted; of those, the structures of approximately 40% were solved by X-ray crystallography. The main driver has been the parallel processing of multiple (typically 9-20) truncated constructs of each target; modest diversity in vectors and host systems; and standardized purification procedures. We provide method details as well as data on the properties of the constructs leading to crystallized proteins and the impact of methodological variants. These can be used to formulate guidelines for initial approaches to expression of new eukaryotic proteins.

Pike ACW, Shrestha B, Popuri V, Burgess-Brown N, Muzzolini L, Costantini S, Vindigni A, Gileadi O. 2009. Structure of the human RECQ1 helicase reveals a putative strand-separation pin. Proc Natl Acad Sci U S A, 106 (4), pp. 1039-1044. | Show Abstract | Read more

RecQ-like helicases, which include 5 members in the human genome, are important in maintaining genome integrity. We present a crystal structure of a truncated form of the human RECQ1 protein with Mg-ADP. The truncated protein is active in DNA fork unwinding but lacks other activities of the full-length enzyme: disruption of Holliday junctions and DNA strand annealing. The structure of human RECQ1 resembles that of Escherichia coli RecQ, with some important differences. All structural domains are conserved, including the 2 RecA-like domains and the RecQ-specific zinc-binding and winged-helix (WH) domains. However, the WH domain is positioned at a different orientation from that of the E. coli enzyme. We identify a prominent beta-hairpin of the WH domain as essential for DNA strand separation, which may be analogous to DNA strand-separation features of other DNA helicases. This hairpin is significantly shorter in the E. coli enzyme and is not required for its helicase activity, suggesting that there are significant differences between the modes of action of RecQ family members.

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