Translesion DNA Synthesis by Yeast DNA Polymerase η on Templates Containing N²-Guanine Adducts of 1,3-Butadiene Metabolites

Yeast DNA polymerase η can replicate through cis-syn cyclobutane pyrimidine dimers and 8-oxoguanine lesions with the same efficiency and accuracy as replication of an undamaged template. Previously, it has been shown that Escherichia coli DNA polymerases I, II, and III are incapable of bypassing DNA substrates containing N²-guanine adducts of stereoisomeric 1,3-butadiene metabolites. Here we showed that yeast polymerase η replicates DNA containing the monoadducts (S)-butadiene monoepoxide and (S,S)-butadiene diolepoxide N²-guanines albeit at an ∼200-300-fold lower efficiency relative to the control guanine. Interestingly, nucleotide incorporation opposite the (R)-butadiene monoepoxide and the (R,R)-butadiene diolepoxide N²-guanines was ∼10-fold less efficient than incorporation opposite their S stereoisomers. Polymerase η preferentially incorporates the correct nucleotide opposite and downstream of all four adducts, except that it shows high misincorporation frequencies for elongation of C paired with (R)-butadiene monoepoxide N ²-guanine. Additionally, polymerase η does not bypass the (R,R)- and (S,S)-butadiene diolepoxide N²-guanine-N²-guanine intra-strand cross-links, and replication is completely blocked just prior to the lesion. Collectively, these data suggest that polymerase η can tolerate the geometric distortions in DNA conferred by the N²-guanine butadiene monoadducts but not the intrastrand cross-links.