Skip Internal Navigation
Overview
Recent studies performed by the Section on Membrane Biology, led by Leonid Chernomordik, is to understand how proteins drive membrane fusion in important cell biology processes. The starting point in the Section's analysis is a consideration of the physical factors that determine the tendency of the membrane bilayers to change their topology. The analysis of the molecular mechanisms of diverse membrane rearrangements will likely bring about new ways of controlling them and clarify the generality of emerging mechanistic insights. In one of its recent projects, the Section focused on fusion mediated by the influenza virus hemagglutinin. Fusion between the viral envelope and the membrane of acidified endosome delivers viral RNA into cytosol. In the initial conformation of hemagglutinin (HA), the transmembrane protein HA2 (HA's fusogenic subunit) is locked in a metastable conformation by the receptor-binding HA1 subunit of HA. The unexpected finding that the final conformation of the HA2 ectodomain mediates fusion between lipid bilayers and between biological membranes suggests that the fusion process is driven by this final conformation rather than by the energy released by protein restructuring into the final form. In another project, the Section explored the late stages of syncytium formation initiated by viral fusogens and found that fusion pore expansion at late stages of cell-to-cell fusion is mediated, directly or indirectly, by intracellular membrane-shaping proteins involved in endocytosis. The work emphasizes an interesting overlap between proteins controlling late stages of cell-to-cell fusion and proteins that drive oppositely directed process of membrane