The Mechanism of Nucleotide Excision Repair-Mediated UV-Induced Mutagenesis in Nonproliferating Cells

摘要

Following the irradiation of nondividing yeast cells with ultraviolet (UV) light, most induced mutations are inherited by both daughter cells, indicating that complementary changes are introduced into both strands of duplex DNA prior to replication. Early analyses demonstrated that such two-strand mutations depend on functional nucleotide excision repair (NER), but the molecular mechanism of this unique type of mutagenesis has not been further explored. In the experiments reported here, an adeX colony-color system was used to examine the genetic control of UV-induced mutagenesis in nondividing cultures of Saccharomyces cerevisiae. We confirmed a strong suppression of two-strand mutagenesis in NER-deficient backgrounds and demonstrated that neither mismatch repair nor interstrand crosslink repair affects the production of these mutations. By contrast, proteins involved in the error-prone bypass of DNA damage (, , , , , and ) and in the early steps of the DNA-damage checkpoint response (, , , , and ) were required for the production of two-strand mutations. There was no involvement, however, for the Pol η translesion synthesis DNA polymerase, the - postreplication repair complex, downstream DNA-damage checkpoint factors (, , and href="http://www.yeastgenome.org/cgi-bin/locus.fpl?dbid=S000002259" data-ga-action="click_feat_suppl" ref="reftype=extlink&article-id=3583999&issue-id=220132&journal-id=301&FROM=Article%7CFront%20Matter&TO=External%7CLink%7CURI" target="_blank">Dun1), or the href="http://www.yeastgenome.org/cgi-bin/locus.fpl?dbid=S000005559" data-ga-action="click_feat_suppl" ref="reftype=extlink&article-id=3583999&issue-id=220132&journal-id=301&FROM=Article%7CFront%20Matter&TO=External%7CLink%7CURI" target="_blank">Exo1 exonuclease. Our data support models in which UV-induced mutagenesis in nondividing cells occurs during the Pol ζ-dependent filling of lesion-containing, NER-generated gaps. The requirement for specific DNA-damage checkpoint proteins suggests roles in recruiting and/or activating factors required to fill such gaps.