Role of Coiled Coils in Viral Infection

Coiled-coil interactions are essential not only for vesicular trafficking during intra-cellular protein and lipid transport and intercellular communication using neuro-transmitters (see Sect. 2.2), but they also constitute an indispensable part of the fusion machinery of enveloped viruses. Viruses have to overcome the membrane of the host cell to deliver their genetic material into the cytosol and nucleus so that a new infectious cycle can be established. Viral entry into host cells proceeds via two functionally distinct steps, namely, recognition of the target cell and fusion of the viral membrane with the cell membrane of the host (for a recent review, see Weissenhorn et al. 2007). While recognition of target cells is appropriately specific and falls beyond the scope of this work, the basic steps leading to membrane fusion are believed to be common to all enveloped viruses, though differences exist as to the mode of activation, the structural motifs used, and the initial state of oligomeri-zation of the viral fusion protein. For the purpose of this review, we restrict our considerations to class I fusion proteins, which are of extraordinary importance from a pharmacological viewpoint. We will first describe the generic functions of these fusion proteins during viral entry into the host cell and then turn our attention to two specific examples, influenza hemagglutinin and HIV gp41.

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