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

ABSTRACT: DNA polymerase ? (pol ?) synthesizes past cyclobutane pyrimidine dimer and possibly 7,8-dihydro-8-oxoguanine (8-oxoG) lesions during DNA replication. Loss of pol ? 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 ?'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 ?. 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.

SUBMITTER: Beardslee RA 

PROVIDER: S-EPMC4120640 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature