Molecular Basis of HIV Accessory and Regulatory Protein Complexes

Northwestern University At Chicago, Evanston IL

Investigators

Abstract

Project Summary/Abstract In addition to the typical retrovirus genes for viral genome replication, integration, and virus maturation, the genome of human immunodeficiency virus-1 (HIV-1) encodes four unique accessory genes. Although not directly involved in the viral genome replication or virus assembly, these HIV-1 accessory proteins play critical roles in maintaining the infectivity of the virus, particularly in the late stages of the HIV lifecycle. During HIV-1 infection, they establish numerous physical interactions with host factors; and typically promote virus infection by intercepting essential host cellular processes, such as antiviral immune response. Some key targets of these HIV accessory proteins have been identified for 20 years, yet the atomic details about their interactions have been elusive for most of them due to the challenges of determining structures of large and labile complexes involving proteins and nucleic acids with traditional structural biology methods—either X-ray crystallography or NMR. Recent advancements in cryogenic electron microscopy (cryoEM) have opened opportunities to analyze these challenging complexes involving HIV-1 accessory, host regulatory proteins, and nucleic acids. For example, recent studies from our groups and two other groups have revealed the mechanistic basis for the HIV-1 accessory protein Vif that hijacks the host ubiquitin ligase to degrade human APOBEC3G antiviral restriction factors in the host T-cells. However, much of HIV-host interaction networks remain uncharacterized. My long-term career aspiration is to become an independent structural biologist with a primary focus on HIV, and contribute to humanity’s yet-to-be fulfilled goal of curbing the devastating AIDS pandemic through rational drug design. This K22 career development proposal outlines a 2-year independent research plan to study the structural basis of HIV accessory proteins Vpr and Vif with known and unknown host factors that they associate with. I have taken advantage of—and will continue to benefit from—the fantastic infrastructure afforded by the UCLA-AIDS institute and learned cutting-edge cryoEM technologies in the Zhou laboratory in UCLA’s California NanoSystems Institute. In Aim 1, I will focus on the previously identified yet structurally uncharacterized important protein complexes involving HIV-1 Vpr and Vif by targeted in vitro reconstitution approaches. In Aim 2, I will apply Dr. Zhou lab’s novel cryoID approach (a cryoEM-based structural proteomics method) to explore and identify novel host interactors of Vpr and Vif. This approach involves the enrichment of the endogenous protein complexes directly from HIV-infected cells for atomic structure determination. Overall, this K22 project would not only bring cutting-edge technologies to bear on challenging HIV/AIDS research, but would also define intricate strategies that HIV adopts to combat host anti-viral factors and to exploit pro-viral factors. The atomic structures from the proposed studies will form the basis of my future R01 grant focusing on structural biology of HIV-host interactions and structure-guided development of antiretroviral therapeutics.