title: Insights into the Molecular Mechanism of Polymerization and Nucleoside Reverse Transcriptase Inhibitor Incorporation by Human PrimPol.
abstract: Human PrimPol is a newly identified DNA and RNA primase-polymerase of the archaeo-eukaryotic primase (AEP) superfamily and only the second known polymerase in the mitochondria. Mechanistic studies have shown that interactions of the primary mitochondrial DNA polymerase γ (mtDNA Pol γ) with nucleoside reverse transcriptase inhibitors (NRTIs), key components in treating HIV infection, are a major source of NRTI-associated toxicity. Understanding the interactions of host polymerases with antiviral and anticancer nucleoside analog therapies is critical for preventing life-threatening adverse events, particularly in AIDS patients who undergo lifelong treatment. Since PrimPol has only recently been discovered, the molecular mechanism of polymerization and incorporation of natural nucleotide and NRTI substrates, crucial for assessing the potential for PrimPol-mediated NRTI-associated toxicity, has not been explored. We report for the first time a transient-kinetic analysis of polymerization for each nucleotide and NRTI substrate as catalyzed by PrimPol. These studies reveal that nucleotide selectivity limits chemical catalysis while the release of the elongated DNA product is the overall rate-limiting step. Remarkably, PrimPol incorporates four of the eight FDA-approved antiviral NRTIs with a kinetic profile distinct from that of mtDNA Pol γ that may manifest in toxicity.
authors.affiliation: Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
authors.forename: Andrea C
authors.initials: AC
authors.lastname: Mislak
authors.affiliation: Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA Karen.Anderson@yale.edu.
authors.forename: Karen S
authors.initials: KS
authors.lastname: Anderson
mesh_terms: D019380:Anti-HIV Agents / Q000378:metabolism*; D003001:Cloning, Molecular; D004247:DNA / Q000096:biosynthesis* / Q000235:genetics; D019915:DNA Primase / Q000235:genetics / Q000378:metabolism*; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism*; D003838:Deoxyadenine Nucleotides / Q000378:metabolism; D003845:Deoxycytosine Nucleotides / Q000378:metabolism; D003848:Deoxyguanine Nucleotides / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D007700:Kinetics; D064251:Multifunctional Enzymes / Q000235:genetics / Q000378:metabolism*; D058105:Polymerization; D011485:Protein Binding; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D018894:Reverse Transcriptase Inhibitors / Q000378:metabolism*; D013936:Thymidine / Q000378:metabolism
chemical_list: D019380:Anti-HIV Agents; D003838:Deoxyadenine Nucleotides; D003845:Deoxycytosine Nucleotides; D003848:Deoxyguanine Nucleotides; D064251:Multifunctional Enzymes; D011994:Recombinant Proteins; D018894:Reverse Transcriptase Inhibitors; D004247:DNA; D019915:DNA Primase; C585901:PrimPol protein, human; D004259:DNA-Directed DNA Polymerase; D013936:Thymidine