Although the structural biology of retroviruses, and in particular of HIV-1, has been pursued for years, many fundamental questions remain unanswered. In particular an in depth understanding is lacking of how the Gag protein is targeted to, and interacts with, the inner leaflet of the plasma membrane (PM). Also, the nature of the Gag lattice that forms at assembly sites underneath the plasma membrane is poorly characterized at a molecular level. This renewal application describes experiments that address these two topics. The application, which is intended as a transition to termination grant, seeks modest funding for a three year period. Many of the proposed experiments are either already in progress or are collaborations in which we supply proteins to other labs. For the latter, we envision our role as catalyzing significant science that may then be continued independently by other labs.
Specific Aim 1 of the proposal is to understand how HIV-1 and Rous sarcoma virus (RSV) Gag proteins interact with membranes. We will extend to inner leaflet lipids our observations on the stimulating effect of cholesterol and certain acyl chains on liposome binding. We will dissect the roles of the MA and NC domains in liposome interaction, and will quantify the effects of multimerization. Finally, we will test one hypothesis that might explain th stimulatory effect of cholesterol on membrane binding of Gag, and in a collaboration will determine if MA and Gag proteins prefer positively or negatively curved membranes.
Specific Aim 2 is to elucidate the structure of the RSV Gag lattice. With collaborators we will attempt to determine the structure of the SP assembly domain in the Gag lattice and also as a peptide, and attempt to determine how dimerization triggers Gag assembly in vitro. We will follow up a crystallization lead for the minimal Gag fragment needed for assembly. Finally, with collaborators we will determine the overall shape of RSV Gag, both in solution and when bound to tethered membranes.

Public Health Relevance

Though the HIV/AIDS epidemic has been slowed, there is continuing need for drugs that target different steps in the virus life cycle. Virus assembly is a promising target but is incompletely understood. This proposal seeks to expand our understanding of two fundamental steps in the retroviral replication cycle, interaction of the vira structural protein (Gag) with the plasma membrane, and assembly of the Gag lattice that comprises the core of the immature virus particle.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM107013-37
Application #
8822890
Study Section
AIDS Molecular and Cellular Biology Study Section (AMCB)
Program Officer
Chin, Jean
Project Start
1977-05-01
Project End
2016-03-31
Budget Start
2015-04-01
Budget End
2016-03-31
Support Year
37
Fiscal Year
2015
Total Cost
$225,216
Indirect Cost
$75,216
Name
Cornell University
Department
Biochemistry
Type
Schools of Earth Sciences/Natur
DUNS #
872612445
City
Ithaca
State
NY
Country
United States
Zip Code
14850
Wen, Yi; Vogt, Volker M; Feigenson, Gerald W (2018) Multivalent Cation-Bridged PI(4,5)P2 Clusters Form at Very Low Concentrations. Biophys J 114:2630-2639
Dick, Robert A; Zadrozny, Kaneil K; Xu, Chaoyi et al. (2018) Inositol phosphates are assembly co-factors for HIV-1. Nature 560:509-512
Doktorova, Milka; Heberle, Frederick A; Kingston, Richard L et al. (2017) Cholesterol Promotes Protein Binding by Affecting Membrane Electrostatics and Solvation Properties. Biophys J 113:2004-2015
Wen, Yi; Dick, Robert A; Feigenson, Gerald W et al. (2016) Effects of Membrane Charge and Order on Membrane Binding of the Retroviral Structural Protein Gag. J Virol 90:9518-32
Dick, Robert A; Barros, Marilia; Jin, Danni et al. (2016) Membrane Binding of the Rous Sarcoma Virus Gag Protein Is Cooperative and Dependent on the Spacer Peptide Assembly Domain. J Virol 90:2473-85
Schur, Florian K M; Dick, Robert A; Hagen, Wim J H et al. (2015) The Structure of Immature Virus-Like Rous Sarcoma Virus Gag Particles Reveals a Structural Role for the p10 Domain in Assembly. J Virol 89:10294-302
Dick, Robert A; Datta, Siddhartha A K; Nanda, Hirsh et al. (2015) Hydrodynamic and Membrane Binding Properties of Purified Rous Sarcoma Virus Gag Protein. J Virol 89:10371-82
Bush, Di L; Monroe, Eric B; Bedwell, Gregory J et al. (2014) Higher-order structure of the Rous sarcoma virus SP assembly domain. J Virol 88:5617-29
Dick, Robert A; Vogt, Volker M (2014) Membrane interaction of retroviral Gag proteins. Front Microbiol 5:187
Dick, Robert A; Kamynina, Elena; Vogt, Volker M (2013) Effect of multimerization on membrane association of Rous sarcoma virus and HIV-1 matrix domain proteins. J Virol 87:13598-608

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