Viruses have a limited number of genes but a complex life cycle. They have hence evolved to utilize numerous host factors to complete their replication. With regard to HIV-1 assembly, a synchronized movement of different viral proteins to specific sites on the plasma membrane enables virion morphogenesis. The host SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins are widely involved in late stages of vesicular mediated transport. These proteins catalyze the docking and fusion of apposing membranes in the vesicle and target compartment. The SNAREs are involved not only in the endocytic and exocytic trafficking pathways but also in other membrane fusion and fission events. These include daughter cell separation during cytokinesis, a phenomenon that bears striking similarity to the process of HIV-1 budding. By generalized disruption of the SNARE sorting machinery, we recently demonstrated a role for these proteins in HIV-1 assembly by affecting Gag localization to the plasma membrane. Preliminary data suggests that SNARE proteins may regulate the cellular trafficking pathways required for Gag association/transport with the plasma membrane. In this study, we propose to define the precise mechanism via which SNARE disruption affects HIV particle production.
We aim to study the effects of SNARE disruption on the cellular proteins and lipid components important for HIV particle production. We will also determine if SNARE disruption affects the integrity of the cellular membrane architecture. Finally, we propose to study whether there is a preferential involvement of specific "v" (vesicle-associated) or "t" (target membrane-associated) SNARE proteins in this process. This will not only define a role for novel host factors in the HIV life ccle but a better understanding of the virus assembly and release pathway will help open avenues for identifying novel anti-viral targets.
HIV-1 particle assembly essentially requires viral structural components as building blocks for a defined structure. When expressed in cells, HIV-1 Gag alone is sufficient to drive the formation of virus like particles. However, viruses are simple organisms and carry the minimal genes necessary for completion of their life cycle. This makes it necessary that these simple pathogens take advantage of the host cellular machinery to complete their replication. The same holds true for the HIV-1 assembly and release pathway. The host SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins play an important role in various cellular sorting processes. We recently described a role for these proteins in HIV particle production. However, the precise mechanism via which the SNARE proteins regulate the HIV-1 assembly and release process remains unknown. In this proposal we aim to decipher the mechanism by which SNARE proteins regulate HIV particle production. We also propose to study the selective involvement if any of specific v (vesicle-associated) or t (target membrane-associated) SNARE proteins in this process. This will not only advance the field of basic HIV biology but a better understanding of the host processes utilized by the virus will help open novel avenues for drug discovery.