Graduate Research Prize Winners 2009
I graduated in 2004 at Padua University (Italy), after a research experience in Dr. Kelleher's laboratory at UNSW, Sidney, Australia, where I studied Interleukin-7 (IL-7) regulation. IL- 7 is a T-cell growth regulator and its systemic levels are abnormally high in HIV infection. I found that IL-7 receptor, CD127, is down-regulated by high IL-7 levels through an internalisation feedback mechanism, providing new insights in T-cell homeostasis and HIV infection.
I then joined the Wellcome Trust Structural Biology PhD program at Oxford University where I benefited from thought courses on structural biology and biophysics techniques as well as rotation in various laboratories.
As a rotation student I worked with Dr. van Thor, describing the molecular mechanisms of the Green Fluorescent Protein (GFP) photocycle by X-ray crystallography and infra-red spectroscopy, and with Professor Campbell, studying the focal adhesion-associated protein paxillin by NMR spectroscopy.
For my D.Phil. I joined Professor Stephen Fuller's Laboratory to study the structure of the Simian Immunodeficiency Virus (SIV) envelope complex (Env) by electron microscopy (EM). This complex is used by the virus to attach to the host cell and mediate fusion of the viral and cellular membranes, an event which leads to infection. Employing cryo-electron tomography and sub-tomogram averaging I solved the in situ three-dimensional structure of Env. The averaged tomographic structure reveals important detail on the architecture of the complex in its native conformation. The work represents an important advancement in both its biological and technical aspects, as it informs on the mechanism of viral cell-invasion and is one of the first examples of membrane protein complexes solved by cryo-electron-tomography.
SIV envelope complex cryo-electron tomographic structure. The envelope complex mediates viral entry and is a target for vaccine and drug design studies. Shown here are a reconstructed virion, three views of the averaged structure of the spike in the membrane, and a slice through a tomogram in the background.
During the second part of my D.Phil, I focussed on the improvement of data processing techniques for cryo-electron tomography, in collaboration with Dr. John Briggs at the EMBL in Heidelberg. One of the major weak points of the averaged cryo-electron tomographic maps obtained previously is their relatively low resolution (between 25 and 30 Amstrong). An important limiting factor comes from instrumental aberrations in EM. I developed methods for detection and computational correction of these aberrations on the images.
At present I am a post-doctoral researcher in Professor Schekman's group, where I am applying cell biology and biochemical techniques to study the ER to Golgi transport of the Sterol Regulatory Element Binding Protein (SREBP).
- Zanetti G, Riches JD, Fuller SD, Briggs JAG. (2009). Contrast transfer function correction applied to cryo-electron tomography and averaging. J Struct Biol 168 (2009):305-312
- Briggs JAG, Riches JD, Glass B, Bartonova V, Zanetti G and Krausslich, HG. (2009). Structure and assembly of immature HIV. Proc Natl Acad Sci USA 106(27):11090-5.
- Zanetti G, Briggs JA, Gruenewald K, Sattentau QJ, Fuller SD. (2006). Cryo-electron tomographic structure of an immunodeficiency virus envelope complex in situ. PLoS Pathog. 2(8):e91
- Staunton D, Schlinkert R, Zanetti G, Colebrook SA, Campbell ID. (2006). Cell-free expression and selective isotope labelling in protein NMR. Magn Reson Chem. 44 Spec No:S2-9
- Sasson SC, Zaunders JJ, Zanetti G, King EM, Merlin KM, Smith DE, Stanley KK, Cooper DA, Kelleher AD. (2006). Increased plasma interleukin-7 level correlates with decreased CD127 and Increased CD132 extracellular expression on T cell subsets in patients with HIV-1 infection. J Infect Dis. 193(4):505-14.
- van Thor JJ, Zanetti G, Ronayne KL, Towrie M. (2005). Structural events in the photocycle of green fluorescent protein. J Phys Chem B. 109(33):16099-108.