Abasic (AP) sites represent one of the most frequently formed lesions in DNA, and they present a strong block to continued synthesis by the replicative DNA polymerases (Pols). Here we determine the mutational specificity and the genetic control of translesion synthesis (TLS) opposite an AP site in yeast by using a double-stranded plasmid system that we have devised in which bidirectional replication proceeds from a replication origin. We find that the rate, the genetic control, and the types and frequencies of nucleotides inserted opposite the AP site are very similar for both the leading and the lagging DNA strands, and that an A is predominantly inserted opposite the AP site, whereas C insertion by Rev1 constitutes a much less frequent event. In striking contrast, in studies that have been reported previously for AP bypass with gapped-duplex and single-stranded plasmids, it has been shown that a C is the predominant nucleotide inserted opposite the AP site. We discuss the implications of our observations for the mechanisms of TLS on the leading versus the lagging DNA strand and suggest that lesion bypass during replication involves the coordination of activities of the replicative Pol with that of the lesion-bypass Pol.
|Original language||English (US)|
|Number of pages||6|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - Jan 29 2008|
- Dna replication
- Translesion DNA synthesis
ASJC Scopus subject areas