Arbel-Eden A, Joseph-Strauss D, Masika H, Printzental O, Rachi E, Simchen G

Trans-lesion DNA polymerases (TLSPs) enable bypass of DNA lesions during replication and are also induced under stress conditions. Being only weakly dependent on their template during replication, TLSPs introduce mutations into DNA. The low processivity of these enzymes ensures that they fall off their template after a few bases are ...

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synthesized and are then replaced by the more accurate replicative polymerase. We find that the three TLSPs of budding yeast Saccharomyces cerevisiae, Rev1, PolZeta (Rev3 & Rev7) and Rad30, are induced during meiosis, at a time when DNA double-strand breaks (DSBs) are formed and homologous chromosomes recombine. Strains deleted for one, or any combination of the three TLSPs, undergo normal meiosis. However, in the triple-deletion mutant there is a reduction in both allelic and ectopic recombination. We suggest that trans-lesion polymerases are involved in the processing of meiotic double-strand breaks and thus lead to mutations. In support of this notion we report significant Yeast-Two-Hybrid (Y2H) associations in meiosis-arrested cells between TLSPs and DSB-proteins - Rev1-Spo11, Rev1-Mei4, Rev7-Rec114, as well as between Rev1 and Rad30. We suggest that the involvement of TLSPs in processing of meiotic DSBs could be responsible for the considerably higher frequency of mutations reported during meiosis compared with that found in mitotically dividing cells, and therefore may contribute to faster evolutionary divergence than previously assumed.

Date: Mar. 11, 2013

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