Substrate mimicry: HIV-1 reverse transcriptase recognizes 6-modified-3 '-azido-2 ',3 '-dideoxyguanosine-5 '-triphosphates as adenosine analogs

• Type of Material: Article
• Authors: Brian D. Herman, University of Pittsburgh; Raymond F Schinazi, Emory University; HongWang Zhang, Emory University; James H Nettles, Emory University; Richard Stanton, Emory University; Mervi Detorio, Emory University; Aleksandr Obikhod, Emory University; Ugo Pradere, Emory University; Steven Coats, Emory University; John W. Mellors, University of Pittsburgh; Nicolas Sluis-Cremer, University of Pittsburgh
• Language: English
• Date: 2012-01-01
• Publisher: Oxford University Press (OUP): Policy C - Option B
• Publication Version: Final Published Version
• Copyright Statement: © 2011 The Author(s).
• License: Creative Commons Attribution-Noncommercial 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1093/nar/gkr756
• Title of Journal or Parent Work: Nucleic Acids Research
• ISSN: 0305-1048
• Volume: 40
• Issue: 1
• Start Page: 381
• End Page: 390
• Grant/Funding Information: Funding for open access charge: National Institutes of Health (grant R01 - AI - 071846).; The National Institutes of Health (R01-AI-071846; to J.W.M., 5P30-AI-050409; to R.F.S., 5R37-AI-041980; to R.F.S., 5R37-AI-025899 to R.F.S.) and the Department of Veterans Affairs (R.F.S.).
• Keywords: AZT; PRIMER; Biochemistry & Molecular Biology; UNBLOCKING; IMMUNODEFICIENCY-VIRUS TYPE-1; MECHANISM; Science & Technology; RESISTANCE; PURIFICATION; EXCISION; Life Sciences & Biomedicine
• Research Categories: Biology, Virology; Health Sciences, Public Health; Health Sciences, Immunology

Abstract

β-D-3′-Azido-2′,3′-dideoxyguanosine (3′-azido-ddG) is a potent inhibitor of HIV-1 replication with a superior resistance profile to zidovudine. Recently, we identified five novel 6-modified-3′-azido-ddG analogs that exhibit similar or superior anti-HIV-1 activity compared to 3′-azido-ddG in primary cells. To gain insight into their structure-activity-resistance relationships, we synthesized their triphosphate (TP) forms and assessed their ability to inhibit HIV-1 reverse transcriptase (RT). Steady-state and pre-steady-state kinetic experiments show that the 6-modified-3′-azido-ddGTP analogs act as adenosine rather than guanosine mimetics in DNA synthesis reactions. The order of potency of the TP analogs against wild-type RT was: 3′-azido-2,6- diaminopurine >3′-azido-6-chloropurine; 3′-azido-6-N- allylaminopurine>2-amino-6-N,N-dimethylaminopurine; 2-amino-6-methoxypurine. Molecular modeling studies reveal unique hydrogen-bonding interactions between the nucleotide analogs and the template thymine base in the active site of RT. Surprisingly, the structure-activity relationship of the analogs differed in HIV-1 RT ATP-mediated excision assays of their monophosphate forms, suggesting that it may be possible to rationally design a modified base analog that is efficiently incorporated by RT but serves as a poor substrate for ATP-mediated excision reactions. Overall, these studies identify a promising strategy to design novel nucleoside analogs that exert profound antiviral activity against both WT and drug-resistant HIV-1.