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

• Published in: The Journal of biological chemistry 2013-11, Vol.288 (46), p.33253-33262
• Main Authors: Van Cor-Hosmer, Sarah K., Kim, Dong-Hyun, Daly, Michele B., Daddacha, Waaqo, Kim, Baek
• Format: Article
• Language: English
• Subjects: Cells, Cultured; Deoxyribonucleotides - metabolism; DNA and Chromosomes; DNA Gap Filling; DNA Polymerase; DNA Polymerase beta - metabolism; DNA Repair; dNTP; Female; HIV-1; HIV-1 - physiology; Humans; Integration; Macrophages; Macrophages - metabolism; Macrophages - virology; Male; Monocytes; Proviruses - physiology; Virus Integration - physiology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M113.486787

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. Background: The cellular DNA repair machinery completes the 5′-end gap repair of HIV-1 integration. Results: The 5′-end DNA gap repair of HIV-1 integration depends on dNTP availability in macrophages, monocytes, and CD4+ T cells. Conclusion: 5′-End DNA gap repair is a rate-limiting step in HIV-1 integration in macrophages and monocytes due to limited cellular dNTPs. Significance: Availability of cellular dNTP and polymerase controls HIV-1 integration kinetics.