HIV-1 Env incorporation and maturation

The formation of infectious HIV-1 particles requires the incorporation of Env glycoproteins during the assembly process, with Env mediating binding of newly released virions to target cells and subsequent entry via fusion between viral and target-cell membranes. The interaction between the MA domain of Gag and gp41 of Env plays a central role in Env incorporation into virions and in the activation of Env fusion activity, yet this interaction remains poorly understood at the biochemical and structural levels. In addition, recent structures of the MA lattice in both immature and mature HIV-1 particles implicate a maturation-induced rearrangement of MA the lattice. This opens the possibility that MA-gp41 interactions are dynamic, and change during the maturation process.

We aim to apply an array of biochemical, structural, super-resolution imaging, and virological approaches that will interrogate the MA/gp41 interaction and will provide novel insights into the mechanism and dynamics of Env incorporation into HIV-1 particles. A set of informative mutants, which display stabilized MA-MA and/or MA-gp41 interactions, will be used for structural studies,. Cryo-ET analysis of intact mature and immature virions will be performed to obtain structural data that will complement the information obtained with the MA/Gag assemblies. Predictions regarding potential sites of MA-MA and MA-gp41 interactions obtained from these structural studies will be tested in Env incorporation and virus replication assays. This combination of structural, biochemical, and virological studies will help to elucidate the mechanism of Env incorporation into HIV-1 particles and the subsequent process of particle maturation.