title: Mutation of the little finger domain in human DNA polymerase η alters fidelity when copying undamaged DNA.
abstract: DNA polymerase η (pol η) synthesizes past cyclobutane pyrimidine dimer and possibly 7,8-dihydro-8-oxoguanine (8-oxoG) lesions during DNA replication. Loss of pol η is associated with an increase in mutation rate, demonstrating its indispensable role in mutation suppression. It has been recently reported that β-strand 12 (amino acids 316-324) of the little finger region correctly positions the template strand with the catalytic core of the enzyme. The authors hypothesized that modification of β-strand 12 residues would disrupt correct enzyme-DNA alignment and alter pol η's activity and fidelity. To investigate this, the authors purified proteins containing the catalytic core of the polymerase, incorporated single amino acid changes to select β-strand 12 residues, and evaluated DNA synthesis activity for each pol η. Lesion bypass efficiencies and replication fidelities when copying DNA-containing cis-syn cyclobutane thymine-thymine dimer and 8-oxoG lesions were determined and compared with the corresponding values for the wild-type polymerase. The results confirm the importance of the β-strand in polymerase function and show that fidelity is most often altered when undamaged DNA is copied. Additionally, it is shown that DNA-protein contacts distal to the active site can significantly affect the fidelity of synthesis.
authors.affiliation: Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, North Carolina.
authors.forename: Renee A
authors.initials: RA
authors.lastname: Beardslee
authors.forename: Samuel C
authors.initials: SC
authors.lastname: Suarez
authors.forename: Shannon M
authors.initials: SM
authors.lastname: Toffton
authors.forename: Scott D
authors.initials: SD
authors.lastname: McCulloch
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D004247:DNA / Q000235:genetics; D004261:DNA Replication / Q000235:genetics*; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary / Q000235:genetics; D000099270:Y-Family DNA Polymerases
chemical_list: D004247:DNA; D004259:DNA-Directed DNA Polymerase; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases
keywords: DNA damage; lesion bypass; mutagenesis; replication fidelity
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