Accuracy of thymine-thymine dimer bypass by Saccharomyces cerevisiae DNA polymerase eta

The Saccharomyces cerevisiae RAD30 gene functions in error-free replication of UV-damaged DNA. RAD30 encodes a DNA polymerase, pol eta, which inserts two adenines opposite the two thymines of a cis-syn thymine-thymine (T-T) d imer, Here we use steady-state kinetics to determine the accuracy of DNA sy nthesis opposite the T-T dimer, Surprisingly, the accuracy of DNA synthesis opposite the damaged DNA is nearly indistinguishable from that opposite no ndamaged DNA, with frequencies of misincorporation of about 10(-2) to 10(-3 ), These studies support the hypothesis that unlike most DNA polymerases, p ol eta is able to tolerate distortions in DNA resulting from damage, which then enables the polymerase to utilize the intrinsic base pairing ability o f the T-T dimer.