title: Evidence for the kinetic partitioning of polymerase activity on G-quadruplex DNA.
abstract: We have investigated the action of the human DNA polymerase ε (hpol ε) and η (hpol η) catalytic cores on G-quadruplex (G4) DNA substrates derived from the promoter of the c-MYC proto-oncogene. The translesion enzyme hpol η exhibits a 6.2-fold preference for binding to G4 DNA over non-G4 DNA, while hpol ε binds both G4 and non-G4 substrates with nearly equal affinity. Kinetic analysis of single-nucleotide insertion by hpol η reveals that it is able to maintain >25% activity on G4 substrates compared to non-G4 DNA substrates, even when the primer template junction is positioned directly adjacent to G22 (the first tetrad-associated guanine in the c-MYC G4 motif). Surprisingly, hpol η fidelity increases ~15-fold when copying G22. By way of comparison, hpol ε retains ~4% activity and has a 33-fold decrease in fidelity when copying G22. The fidelity of hpol η is ~100-fold greater than that of hpol ε when comparing the misinsertion frequencies of the two enzymes opposite a tetrad-associated guanine. The kinetic differences observed for the B- and Y-family pols on G4 DNA support a model in which a simple kinetic switch between replicative and TLS pols could help govern fork progress during G4 DNA replication.
authors.affiliation: †Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, United States.
authors.forename: Sarah
authors.initials: S
authors.lastname: Eddy
authors.affiliation: †Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, United States.
authors.forename: Leena
authors.initials: L
authors.lastname: Maddukuri
authors.affiliation: †Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, United States.
authors.forename: Amit
authors.initials: A
authors.lastname: Ketkar
authors.affiliation: †Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, United States.
authors.forename: Maroof K
authors.initials: MK
authors.lastname: Zafar
authors.affiliation: ‡Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, Louisiana 70112, United States.
authors.forename: Erin E
authors.initials: EE
authors.lastname: Henninger
authors.affiliation: ‡Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, Louisiana 70112, United States.
authors.forename: Zachary F
authors.initials: ZF
authors.lastname: Pursell
authors.affiliation: †Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, United States.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Eoff
mesh_terms: D020137:Base Pair Mismatch; D004257:DNA Polymerase II / Q000737:chemistry*; D017931:DNA Primers / Q000737:chemistry; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry*; D054856:G-Quadruplexes; D006801:Humans; D007700:Kinetics; D011485:Protein Binding; D000090063:Proto-Oncogene Mas; D013379:Substrate Specificity; D000099270:Y-Family DNA Polymerases
chemical_list: D004257:DNA Polymerase II; D017931:DNA Primers; D004259:DNA-Directed DNA Polymerase; D000090063:Proto-Oncogene Mas; C000715470:MAS1 protein, human; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases