BMSSI : Bases Moléculaires et Structurales des Systèmes Infectieux - UMR 5086

Our researches are centered on the structural and functional analysis of the (membrane) proteins of the hepatitis C virus (HCV) on one hand, and the development of new tools in solid state NMR to determine the 3D structures of insoluble proteins such as fibrils and membrane proteins, which are not obtainable by x-ray crystallography on the other. To advance in understanding the molecular mechanisms underlaying cellular biological processes, our structural studies are done in close collaboration with virologists and biologists involved in the functional analyses of the studied proteins in the cellular context.
To further develop NMR approaches for conformational analyses and 3D structure determination of insoluble proteins, we study biological systems accessible to solid-state NMR studies. These include proteins involved in neurodegenerative diseases which form fibrillar structures such as prion proteins and α-synuclein. We also work on the overexpression, purification and crystallization of new and specifically 13C/15N labeled protein models to implement and test protocols for NMR structure determination, including sequential assignments, measurement of restraints and structure calculation. We also work on structural studies of membrane-bound proteins, by combined liquid/solid-state NMR approaches. As these proteins are often toxic for bacteria, we develop alternative production in cell-free systems using wheat-germ extracts.

Hepatitis C virus (HCV) infection is a major cause of chronic hepatitis, liver cirrhosis and hepatocellular carcinoma worldwide (180 million affected people). As no protective vaccine exists and as the efficiency of current anti-HCV therapies is limited, there is an urgent need to develop more effective and better-tolerated therapies. In this context, our objective is to provide detailed structure analyses of HCV (membrane) proteins as a framework for molecular understanding of the mechanisms of HCV processing, replication, and assembly, as well as the interactions of HCV proteins with host cell components. For analyzing the structural features of the ten HCV proteins, we aim to use NMR and various other biophysical methods, including molecular modeling, circular dichroism, electron microscopy, fluorescence spectroscopy and surface plasmon resonance. We mainly focus on the structure analyses and assembly of the HCV membrane-binding domains, with the main goal of identifying new viral targets for potential therapeutic intervention.