The post-replication repair RAD18 and RAD6 genes are involved in the prevention of spontaneous mutations caused by 7,8-dihydro-8-oxoguanine in Saccharomyces cerevisiae
The post-replication repair RAD18 and RAD6 genes are involved in the prevention of spontaneous mutations caused by 7,8-dihydro-8-oxoguanine in Saccharomyces cerevisiae
复制标题
DOI：
10.1093/nar/gkh831
复制
发表时间：
2004-01-01
影响因子：
14.9
通讯作者：
Boiteux, S
中科院分区：
文献类型：
--
作者：
de Padula, M;Slezak, G;Boiteux, S
7，8-二氢-8-氧代鸟嘌呤（8-oxoG）是在暴露于自由基和活性氧物质的DNA中产生的丰富的和致突变的损伤。在酿酒酵母中，OGG 1基因编码8-oxoG DNA N-糖基化酶/AP裂解酶（Ogg 1），其是细菌Fpg的功能同源物。Ogg 1缺陷型菌株是自发的突变体，由于DNA中未修复的8-oxoG而积累GC至TA的颠换。在酵母中，DNA错配修复（MMR）和DNA聚合酶eta的跨损伤合成（TLS）也在预防8-oxoG的致突变作用中发挥作用。在本研究中，我们显示启动复制后修复（PRR）所需的RAD 18和RAD 6基因也参与了8-oxoG预防突变。一致地，在ogg 1突变株中，在不存在Rad 6或Rad 18蛋白的情况下观察到自发Can（R）和Lys（+）突变率的协同增加。ogg 1 rad 18和ogg 1 rad 6双突变体中的Can（R）突变谱显示出有利于GC至TA颠换的强烈偏好，其分别比野生型高137倍和189倍。结果还表明，Poleta（RAD 30基因产物）在预防8-oxoG突变方面起着关键作用，而Polzeta（REV 3基因产物）则没有。我们目前的模型表明，Rad 6-Rad 18复合物靶向Poleta的DNA缺口，导致从MMR介导的切除腺嘌呤错配与8-oxoG，允许无错误的dCMP掺入相反，这种病变。
7,8-Dihydro-8-oxoguanine (8-oxoG) is an abundant and mutagenic lesion produced in DNA exposed to free radicals and reactive oxygen species. In Saccharomyces cerevisiae, the OGG1 gene encodes the 8-oxoG DNA N-glycosylase/AP lyase (Ogg1), which is the functional homologue of the bacterial Fpg. Ogg1-deficient strains are spontaneous mutators that accumulate GC to TA transversions due to unrepaired 8-oxoG in DNA. In yeast, DNA mismatch repair (MMR) and translesion synthesis (TLS) by DNA polymerase eta also play a role in the prevention of the mutagenic effect of 8-oxoG. In the present study, we show the RAD18 and RAD6 genes that are required to initiate post-replication repair (PRR) are also involved in the prevention of mutations by 8-oxoG. Consistently, a synergistic increase in spontaneous Can(R) and Lys(+) mutation rates is observed in the absence of Rad6 or Rad18 proteins in ogg1 mutant strains. Spectra of Can(R) mutations in ogg1 rad18 and ogg1 rad6 double mutants show a strong bias in the favor of GC to TA transversions, which are 137- and 189-fold higher than in the wild-type, respectively. The results also show that Poleta (RAD30 gene product) plays a critical role on the prevention of mutations at 8-oxoG, whereas Polzeta (REV3 gene product) does not. Our current model suggests that the Rad6-Rad18 complex targets Poleta at DNA gaps that result from the MMR-mediated excision of adenine mispaired with 8-oxoG, allowing error-free dCMP incorporation opposite to this lesion.