title: Host SAMHD1 protein promotes HIV-1 recombination in macrophages.
abstract: Template switching can occur during the reverse transcription of HIV-1. Deoxynucleotide triphosphate (dNTP) concentrations have been biochemically shown to impact HIV-1 reverse transcriptase (RT)-mediated strand transfer. Lowering the dNTP concentrations promotes RT pausing and RNA template degradation by RNase H activity of the RT, subsequently leading to strand transfer. Terminally differentiated/nondividing macrophages, which serve as a key HIV-1 reservoir, contain extremely low dNTP concentrations (20-50 nm), which results from the cellular dNTP hydrolyzing sterile α motif and histidine aspartic domain containing protein 1 (SAMHD1) protein, when compared with activated CD4(+) T cells (2-5 μm). In this study, we first observed that HIV-1 template switching efficiency was nearly doubled in human primary macrophages when compared with activated CD4(+) T cells. Second, SAMHD1 degradation by viral protein X (Vpx), which elevates cellular dNTP concentrations, decreased HIV-1 template switching efficiency in macrophages to the levels comparable with CD4(+) T cells. Third, differentiated SAMHD1 shRNA THP-1 cells have a 2-fold increase in HIV-1 template switching efficiency. Fourth, SAMHD1 degradation by Vpx did not alter HIV-1 template switching efficiency in activated CD4(+) T cells. Finally, the HIV-1 V148I RT mutant that is defective in dNTP binding and has DNA synthesis delay promoted RT stand transfer when compared with wild type RT, particularly at low dNTP concentrations. Here, we report that SAMHD1 regulation of the dNTP concentrations influences HIV-1 template switching efficiency, particularly in macrophages.
authors.affiliation: From the Departments of Pathology and Laboratory Medicine and.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Nguyen
authors.forename: Dong-Hyun
authors.initials: DH
authors.lastname: Kim
authors.forename: Michele B
authors.initials: MB
authors.lastname: Daly
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Allan
authors.forename: Baek
authors.initials: B
authors.lastname: Kim
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000821:virology; D015658:HIV Infections / Q000276:immunology* / Q000821:virology; D054303:HIV Reverse Transcriptase / Q000235:genetics*; D015497:HIV-1 / Q000235:genetics*; D059765:Homologous Recombination / Q000235:genetics; D006801:Humans; D008264:Macrophages / Q000166:cytology / Q000276:immunology / Q000821:virology*; D009000:Monocytes / Q000166:cytology / Q000276:immunology / Q000821:virology; D020559:Monomeric GTP-Binding Proteins / Q000276:immunology*; D061251:Primary Cell Culture; D048348:Reverse Transcription / Q000235:genetics; D016914:Ribonuclease H / Q000378:metabolism; D000076106:SAM Domain and HD Domain-Containing Protein 1; D014779:Virus Replication / Q000235:genetics
chemical_list: C514824:reverse transcriptase, Human immunodeficiency virus 1; D054303:HIV Reverse Transcriptase; D016914:Ribonuclease H; D000076106:SAM Domain and HD Domain-Containing Protein 1; C484280:SAMHD1 protein, human; D020559:Monomeric GTP-Binding Proteins
keywords: HIV-1; Homologous Recombination; Macrophages; Nucleotide; Reverse Transcription; SAMHD1; Vpx