The objectives of this proposal are to learn about the principles that govern the assembly of retrovirus particles at the plasma membrane of the infected cell. The formation of virus particles requires protein-membrane interactions, protein-protein interactions, and protein-RNA interactions. In addition, proteolytic cleavages take place in the maturation of virus particles. Using as a model system the avian sarcoma and leukemia viruses, we will continue to investigate each of these aspects of assembly. 1. Point mutations that render the viral protease defective will be introduced into the viral genome, and quail cell lines will be derived that produce the defective particles. The biochemical properties of these presumably immature virus particles will be characterized. Also, the regulation of protease activity will be studied in vitro, from partially purified protease fusion proteins obtained from an expression vector in E. coli. 2. The site of interaction of gag protein with lipids in the viral membrane will be studied, using different cross-linking agents. Both normal virus and protease-defective virus containing the uncleaved gag precursor protein Pr76 will be analyzed. Further, the interaction of Pr76 made in vitro with chicken membranes will be characterized to learn if this is a biologically relevant model. Studies will be continued to reconstitute phospholipids around delipidated immature virus cores. 3. Detailed deletion and linker scanning mutagenesis of defined 5' and 3' regions on the RNA will be carried out, in order to learn exactly what RNA sequences are required for an RNA to be recognized and efficiently packaged into virus particles. The interaction of Pr76 with viral RNA will be studied in vitro, and in vivo using protease-defective particles and cross-linking techniques. The intent of these experiments is to learn what RNA sequences Pr76 interacts specifically with, and what domains on Pr76 are involved in this interaction. Also, a series of experiments will be carried out to learn what gag proteins interact with newly synthesized viral DNA. 4. The minimum portion of the gag gene needed for formation of a virus particle will be determined using a series of nested deletion mutants. The mechanism by which gag protein inside the virus particle interacts with env protein on the surface will be investigated using several different crosslinking agents. Finally, an attempt will be made to clone a chicken gene that when introduced into mammalian cells, allows these normally non- permissive cells to assemble avian retrovirus particles.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37CA020081-19
Application #
2086800
Study Section
Special Emphasis Panel (NSS)
Project Start
1977-05-01
Project End
1996-07-31
Budget Start
1995-08-01
Budget End
1996-07-31
Support Year
19
Fiscal Year
1995
Total Cost
Indirect Cost
Name
Cornell University
Department
Biochemistry
Type
Schools of Arts and Sciences
DUNS #
City
Ithaca
State
NY
Country
United States
Zip Code
14850
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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Chan, Jany; Dick, Robert A; Vogt, Volker M (2011) Rous sarcoma virus gag has no specific requirement for phosphatidylinositol-(4,5)-bisphosphate for plasma membrane association in vivo or for liposome interaction in vitro. J Virol 85:10851-60
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Taylor, Gwen M; Ma, Lixin; Vogt, Volker M et al. (2010) NMR relaxation studies of an RNA-binding segment of the rous sarcoma virus gag polyprotein in free and bound states: a model for autoinhibition of assembly. Biochemistry 49:4006-17
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Jorgenson, Rebecca L; Vogt, Volker M; Johnson, Marc C (2009) Foreign glycoproteins can be actively recruited to virus assembly sites during pseudotyping. J Virol 83:4060-7
Keller, Paul W; Johnson, Marc C; Vogt, Volker M (2008) Mutations in the spacer peptide and adjoining sequences in Rous sarcoma virus Gag lead to tubular budding. J Virol 82:6788-97
Zhou, Jing; Bean, Rebecca L; Vogt, Volker M et al. (2007) Solution structure of the Rous sarcoma virus nucleocapsid protein: muPsi RNA packaging signal complex. J Mol Biol 365:453-67
Saad, Jamil S; Kim, Andrew; Ghanam, Ruba H et al. (2007) Mutations that mimic phosphorylation of the HIV-1 matrix protein do not perturb the myristyl switch. Protein Sci 16:1793-7

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