Interplay of the HIV-1 Env cytoplasmic tail, Gag-MA, and membrane: resolving molecular detail and blocking assembly

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PROJECT SUMMARY/ABSTRACT The goal of this innovative project is to bring together multidisciplinary expertise to dissect the functional, structural, and dynamic nature of interactions between the HIV-1 envelope (Env) cytoplasmic tail (CT), the underlying Gag matrix (MA) lattice, and the lipid containing membrane in the context of native virions. We will utilize state-of-the-art cryo-electron tomography (cryo-ET), molecular dynamics (MD) simulations, modeling, and in vitro studies to produce a comprehensive rendition of how interactions between these key determinants of assembly and infectivity are orchestrated. Our studies are based on recent cryo-ET data in which the positioning of Env CT and MA interactions differed from previous models. In Aim 1, we will harness the power of cryo-ET to advance the resolution of Env CT-MA interactions to facilitate further interrogation of the mechanics of Env CT- MA-membrane interactions. In Aim 2, we will generate atomistic models of Env CT-MA in the context of the viral membrane using high resolution structures and cryo-ET density, and strategic mutations and truncations of Env CT and MA. In Aim 3, we will exploit conserved structural features to design novel antiviral agents comprised of membrane-permeable cyclic peptide inhibitors. These Aims are supported by comprehensive biochemical and virologic approaches and will use a well characterized clade C transmitted/founder (T/F) HIV-1 infectious molecular clone that is fully representative of global isolates and presents fully matched Env and Gag components, which distinguishes our work. Our studies will reveal in unprecedented detail how Env CT, MA, and membrane lipids engage one another, with all components in near native context. These powerful approaches will produce an integrated model, including flexible regions that are difficult to resolve, to bring the complete Env- MA-membrane machinery to life.