The overall goal of the proposed research is to test a series of hypotheses relating to the molecular details of human immunodeficiency virus type 1 (HIV-1) and Moloney murine leukemia virus (M-MuLV) replication. Biochemical and genetic approaches will be employed to study the DNA polymerase and RNase H activities of reverse transcriptases. The work will focus on the roles and specificities of RNase H during reverse transcription and on the mechanism and fidelity of DNA displacement synthesis by the DNA polymerase. Recent findings on the nucleotide specificity of RNase H at internal cleavage sites will be extended to determine the relative importance of each of the positions where base preferences are observed and how nucleotide sequence preferences influence both RNA 5' end-directed and recessed DNA primer-directed cleavages. Since an RNA 5' end at a nick is ignored by RNases H, the gap size that is required for 5' end-directed cleavage will be determined. The hypothesis that DNA primer-dependent cleavage at a pause site during minus-strand synthesis, rather than internal cleavage, is responsible for generating the HIV-1 plus-strand primer will be tested. A comprehensive series of biochemical and genetic assays will be employed to determine whether the fidelity of HIV-1 reverse transcriptase during displacement synthesis is different from the fidelity of the enzyme during nondisplacement synthesis. Our in vitro finding that hairpin-induced pausing by reverse transcriptase leads to an increase in strand transfers will be extended to an analysis of the effect of hairpins on direct repeat recombination during reverse transcription in vivo. The same in vivo system will be utilized to examine the ability of select reverse transcriptase mutants to carry out RNA displacement synthesis. An in vitro system based on an RNA that contains the essential viral R-U5- PBS-PPT-U3-R sequences will be developed to test the hypothesis that reverse transcriptase in combination with the nucleocapsid protein is capable of carrying out all of the steps of reverse transcription in vitro. These studies will enhance our understanding of key molecular steps of HIV-1 replication. Such findings are crucial to the identification of novel drug targets and to the development and testing of new drugs for the treatment of AIDS. The analysis of reverse transcriptase fidelity during displacement synthesis will directly contribute to our understanding of how the virus rapidly evolves during progression to AIDS.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA051605-17
Application #
7095227
Study Section
AIDS Molecular and Cellular Biology Study Section (AMCB)
Program Officer
Read-Connole, Elizabeth Lee
Project Start
1989-09-30
Project End
2010-04-30
Budget Start
2006-05-01
Budget End
2007-04-30
Support Year
17
Fiscal Year
2006
Total Cost
$284,639
Indirect Cost
Name
University of Washington
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
605799469
City
Seattle
State
WA
Country
United States
Zip Code
98195
Schultz, Sharon J; Zhang, Miaohua; Champoux, James J (2010) Multiple nucleotide preferences determine cleavage-site recognition by the HIV-1 and M-MuLV RNases H. J Mol Biol 397:161-78
Champoux, James J; Schultz, Sharon J (2009) Ribonuclease H: properties, substrate specificity and roles in retroviral reverse transcription. FEBS J 276:1506-16
Schultz, Sharon J; Zhang, Miaohua; Champoux, James J (2009) Preferred sequences within a defined cleavage window specify DNA 3' end-directed cleavages by retroviral RNases H. J Biol Chem 284:32225-38
Schultz, Sharon J; Champoux, James J (2008) RNase H activity: structure, specificity, and function in reverse transcription. Virus Res 134:86-103
Paulson, Benjamin A; Zhang, Miaohua; Schultz, Sharon J et al. (2007) Substitution of alanine for tyrosine-64 in the fingers subdomain of M-MuLV reverse transcriptase impairs strand displacement synthesis and blocks viral replication in vivo. Virology 366:361-76
Schultz, Sharon J; Zhang, Miaohua; Champoux, James J (2006) Sequence, distance, and accessibility are determinants of 5'-end-directed cleavages by retroviral RNases H. J Biol Chem 281:1943-55
Lanciault, Christian; Champoux, James J (2006) Pausing during reverse transcription increases the rate of retroviral recombination. J Virol 80:2483-94
Schultz, Sharon J; Zhang, Miaohua; Champoux, James J (2004) Recognition of internal cleavage sites by retroviral RNases H. J Mol Biol 344:635-52
Winshell, Jamie; Paulson, Benjamin A; Buelow, Ben D et al. (2004) Requirements for DNA unpairing during displacement synthesis by HIV-1 reverse transcriptase. J Biol Chem 279:52924-33
Lanciault, Christian; Champoux, James J (2004) Single unpaired nucleotides facilitate HIV-1 reverse transcriptase displacement synthesis through duplex RNA. J Biol Chem 279:32252-61

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