Kinetic variations between reverse transcriptases of viral protein X coding and noncoding lentiviruses

• Type of Material: Article
• Authors: Gina M Lenzi, Emory University; Robert Domaoal, Emory University; Raymond Schinazi, Emory University; Baek Kim, Emory University
• Language: English
• Date: 2014-12-19
• Publisher: BioMed Central
• Publication Version: Final Published Version
• Copyright Statement: © Lenzi et al.; licensee BioMed Central.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1186/s12977-014-0111-y
• Title of Journal or Parent Work: Retrovirology
• ISSN: 1742-4690
• Volume: 11
• Issue: 1
• Start Page: 111
• End Page: 111
• Grant/Funding Information: This study was supported by NIH AI049781 (B.K.), GM104198 (B.K.), 5P30-AI-50409 Emory Centers for AIDS Research (CFAR), and Department of Veterans Affairs.; We would like to thank Dr. Joseph Hollenbaugh for reading this manuscript.
• Keywords: Vpx; Virology; Reverse transcriptase; Life Sciences & Biomedicine; Science & Technology; Lentivirus; Enzyme kinetics; SAMHD1; LEUKEMIA-VIRUS; dNTPs; HIV-1 RESTRICTION; IMMUNODEFICIENCY-VIRUS TYPE-1; Macrophages; MYELOID CELLS; VPX; POOL; FIDELITY; RESTRICTION FACTOR SAMHD1; MONOCYTE-DERIVED MACROPHAGES
• Research Categories: Biology, Molecular; Biology, Genetics; Biology, Cell

Abstract

Background Host SAM domain and HD domain-containing protein 1 (SAMHD1) suppresses reverse transcription kinetics of HIV-1 in nondividing cells such as macrophages by hydrolyzing and nearly depleting cellular dNTPs, which are the substrates of viral reverse transcriptase (RT). However, unlike HIV-1, HIV-2 and SIVsm encode viral protein X (Vpx), which counteracts the dNTPase activity of SAMHD1 and elevates dNTP concentration, allowing the viruses to replicate under abundant dNTP conditions even in nondividing cells. Findings Here we tested whether RTs of these Vpx coding and noncoding lentiviruses display different enzyme kinetic profiles in response to dNTP concentrations. For this test, we characterized an extensive collection of RTs from 7 HIV-1 strains, 4 HIV-2 strains and 7 SIV strains, and determined their steady-state kinetic parameters. The Km values of all HIV-1 RTs were consistently low and close to the low dNTP concentrations found in macrophages. However, the Km values of SIV and HIV-2 RTs were not only higher than those of HIV-1 RTs but also varied significantly, indicating that HIV-2/SIV RTs require higher dNTP concentrations for efficient DNA synthesis, compared to HIV-1 RT. However, the kcat values of all eighteen lentiviral RTs were very similar. Conclusions Our biochemical analysis supports the hypothesis that the enzymological properties, particularly, Km values, of lentivirus RTs, are mechanistically tied with the cellular dNTP availability in nondividing target cells, which is controlled by SAMHD1 and Vpx.