Title: Mutation of the little finger domain in human DNA polymerase ýý alters fidelity when copying undamaged DNA.

Authors: Beardslee, Renee A; Suarez, Samuel C; Toffton, Shannon M; McCulloch, Scott D

Published In Environ Mol Mutagen, (2013 Oct)

Abstract: DNA polymerase ýý (pol ýý) synthesizes past cyclobutane pyrimidine dimer and possibly 7,8-dihydro-8-oxoguanine (8-oxoG) lesions during DNA replication. Loss of pol ýý is associated with an increase in mutation rate, demonstrating its indispensable role in mutation suppression. It has been recently reported that *-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 *-strand 12 residues would disrupt correct enzyme-DNA alignment and alter pol ýý'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 *-strand 12 residues, and evaluated DNA synthesis activity for each pol ýý. 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 *-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.

PubMed ID: 23913529

MeSH Terms: Amino Acid Motifs; Amino Acid Sequence; DNA Replication/genetics*; DNA-Directed DNA Polymerase/chemistry; DNA-Directed DNA Polymerase/genetics*; DNA-Directed DNA Polymerase/metabolism; DNA/genetics; Humans; Molecular Sequence Data; Mutation; Protein Binding; Protein Structure, Tertiary/genetics