HIV-1 is the causative agent of AIDS. Three viral enzymes - RT, integrase (IN), and protease (PR) - have essential roles in the replication of HIV-1. We are engaged in a long-term effort to study HIV-1 RT, with the expectation that this information will be useful in the development of more effective anti-RT drugs. Our strategy has involved the synthesis, using recombinant DNA techniques, of both wild-type and mutant HIV-1 RTs, including drug-resistant mutants. Some of this purified RT has been used by our long-term collaborator, Edward Arnold (Rutgers University), for structural studies. We have used purified HIV-1 RT to study the biochemical properties of RT mutants, including drug-resistant mutants, and in some cases, have compared the properties of HIV-1 RT to other retroviral RTs, primarily murine leukemia virus (MLV) RT. A major focus of our recent work on HIV-1 RT is the mechanism(s) of nucleoside RT inhibitor (NRTI) resistance. NRTIs are widely used to treat HIV-1 infections; however, there are serious problems with drug toxicity and with the development of resistance. Two of the commonly used NRTIs, 3TC and AZT, have elements (""""""""handles"""""""") that project beyond the corresponding positions of normal dNTPs. 3TC- and AZT-resistant HIV-1 RTs take advantage of these handles and use steric hindrance to block the incorporation of 3TC and to enhance the excision of AZT. Unfortunately, there are HIV-1 RTs that are resistant to NRTIs that do not have obvious handles. We plan to continue to investigate the mechanisms that underlie drug resistance - in particular, we want to understand the mechanisms that underlie resistance to multiple NRTIs. We will ask whether the newly approved drug, tenofovir, will be efficiently excised by RTs that can excise a number of NRTIs. We have started a collaboration with a skilled nucleoside chemist, Victor Marquez (Laboratory of Medicinal Chemistry, NCI); we will ask if it is possible to develop a class of nucleoside analogs that are relatively resistant to excision by HIV-1 RTs that can excise multiple NRTIs. All of these experiments involve a combined structural/biochemical approach; what we have learned from RT structure has been an invaluable guide for planning the biochemical studies, while the results and hypothesis generated in the biochemical experiments have inspired new rounds of structural experiments. NRTI resistance is only one aspect of the behavior of RT. We also want to understand how RT carries out reverse transcription in an infected cell, and to correlate the wealth of structural and biochemical data on HIV-1 RT with the actual process of reverse transcription. These experiments are part of Project Z01 CCR 010482 (Retroviral Replication and Vector Design). In some cases, it will not be possible to explain the in vivo data with the available structural and biochemical results. In such cases, we will do additional biochemical and structural experiments to complement (and better understand) the in vivo results.

Agency
National Institute of Health (NIH)
Institute
Division of Basic Sciences - NCI (NCI)
Type
Intramural Research (Z01)
Project #
1Z01BC010481-01
Application #
6952066
Study Section
(RRL)
Project Start
Project End
Budget Start
Budget End
Support Year
1
Fiscal Year
2003
Total Cost
Indirect Cost
Name
Basic Sciences
Department
Type
DUNS #
City
State
Country
United States
Zip Code
Russ, Pamela L; Gonzalez-Moa, Maria J; Vu, B Christie et al. (2009) North- and south-bicyclo[3.1.0]hexene nucleosides: the effect of ring planarity on anti-HIV activity. ChemMedChem 4:1354-63
Mulky, Alok; Vu, B Christie; Conway, Joan A et al. (2007) Analysis of amino acids in the beta7-beta8 loop of human immunodeficiency virus type 1 reverse transcriptase for their role in virus replication. J Mol Biol 365:1368-78
Wu, Chia-Kuei; Gousset, Karine; Hughes, Stephen H (2007) Targeting to the endoplasmic reticulum improves the folding of recombinant human telomerase reverse transcriptase. Protein Expr Purif 56:8-19
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Jones, Fatima D; Hughes, Stephen H (2007) In vitro analysis of the effects of mutations in the G-tract of the human immunodeficiency virus type 1 polypurine tract on RNase H cleavage specificity. Virology 360:341-9
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Morningstar, Marshall L; Roth, Thomas; Farnsworth, David W et al. (2007) Synthesis, biological activity, and crystal structure of potent nonnucleoside inhibitors of HIV-1 reverse transcriptase that retain activity against mutant forms of the enzyme. J Med Chem 50:4003-15
Boyer, Paul L; Sarafianos, Stefan G; Clark, Patrick K et al. (2006) Why do HIV-1 and HIV-2 use different pathways to develop AZT resistance? PLoS Pathog 2:e10
Marquez, Victor E; Hughes, Stephen H; Sei, Shizuko et al. (2006) The history of N-methanocarbathymidine: the investigation of a conformational concept leads to the discovery of a potent and selective nucleoside antiviral agent. Antiviral Res 71:268-75
Boyer, Paul L; Julias, John G; Marquez, Victor E et al. (2005) Fixed conformation nucleoside analogs effectively inhibit excision-proficient HIV-1 reverse transcriptases. J Mol Biol 345:441-50

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