Restricted 5 '-End Gap Repair of HIV-1 Integration Due to Limited Cellular dNTP Concentrations in Human Primary Macrophages

• Type of Material: Article
• Authors: Sarah K. Van Cor-Hosmer, University of Rochester; Dong-Hyun Kim, Kyung-Hee University; Michele B. Daly, Emory University; Waaqo Daddacha, University of Rochester; Baek Kim, Emory University
• Language: English
• Date: 2013-11-15
• Publisher: American Society for Biochemistry and Molecular Biology
• Publication Version: Final Published Version
• Copyright Statement: © 2013 by The American Society for Biochemistry and Molecular Biology, Inc.
• Final Published Version (URL): http://dx.doi.org/10.1074/jbc.M113.486787
• Title of Journal or Parent Work: Journal of Biological Chemistry
• ISSN: 0021-9258
• Volume: 288
• Issue: 46
• Start Page: 33253
• End Page: 33262
• Grant/Funding Information: This work was supported, in whole or in part, by National Institutes of Health Grants AI049781 (to B. K.) and F31 GM095190 (to W. D.).
• Keywords: REPLICATION; Monocytes; Science & Technology; TYPE-1 REVERSE-TRANSCRIPTASE; CELLS; HIV-1; HUMAN-IMMUNODEFICIENCY-VIRUS; dNTP; POLYMERASE-BETA; RETROVIRAL DNA INTEGRATION; HUMAN MONOCYTES; Integration; DNA Polymerase; PROTEIN; DNA Gap Filling; IN-VITRO; Biochemistry & Molecular Biology; CENTRAL POLYPURINE TRACT; DNA Repair; Macrophages; Life Sciences & Biomedicine
• Research Categories: Chemistry, Biochemistry; Biology, Virology

Abstract

HIV-1 proviral DNA integration into host chromosomal DNA is only partially completed by the viral integrase, leaving two single-stranded DNA gaps with 5′-end mismatched viral DNA flaps. It has been inferred that these gaps are repaired by the cellular DNA repair machinery. Here, we investigated the efficiency of gap repair at integration sites in different HIV-1 target cell types. First, we found that the general gap repair machinery in macrophages was attenuated compared with that in dividing CD4+ T cells. In fact, the repair in macrophages was heavily reliant upon host DNA polymerase β (Pol β). Second, we tested whether the poor dNTP availability found in macrophages is responsible for the delayed HIV-1 proviral DNA integration in this cell type because the Km value of Pol β is much higher than the dNTP concentrations found in macrophages. Indeed, with the use of a modified quantitative AluI PCR assay, we demonstrated that the elevation of cellular dNTP concentrations accelerated DNA gap repair in macrophages at HIV-1 proviral DNA integration sites. Finally, we found that human monocytes, which are resistant to HIV-1 infection, exhibited severely restricted gap repair capacity due not only to the very low levels of dNTPs detected but also to the significantly reduced expression of Pol β. Taken together, these results suggest that the low dNTP concentrations found in macrophages and monocytes can restrict the repair steps necessary for HIV-1 integration.