CELLULAR ROLE OF YEAST APN1 APURINIC ENDONUCLEASE 3'-DIESTERASE - REPAIR OF OXIDATIVE AND ALKYLATION DNA DAMAGE AND CONTROL OF SPONTANEOUS MUTATION
CELLULAR ROLE OF YEAST APN1 APURINIC ENDONUCLEASE 3'-DIESTERASE - REPAIR OF OXIDATIVE AND ALKYLATION DNA DAMAGE AND CONTROL OF SPONTANEOUS MUTATION
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DOI：
10.1128/mcb.11.9.4537
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发表时间：
1991-09-01
影响因子：
5.3
通讯作者：
DEMPLE, B
中科院分区：
文献类型：
--
作者：
RAMOTAR, D;POPOFF, SC;DEMPLE, B
酿酒酵母APN1基因编码酵母细胞提取液中主要的脱嘌呤/脱嘧啶核酸内切酶和3‘-修复DNA二酯酶。Apn1蛋白是大肠杆菌核酸内切酶IV的同源物，它在修复该生物体中的一些氧化和烷基化损伤方面发挥作用。我们在这里表明，缺乏Apn1的酵母菌株(由靶向基因破坏或缺失-替换产生)对氧化(过氧化氢和叔丁基氢过氧化氢)和烷基化(甲基和乙基甲烷磺酸)破坏DNA的试剂都高度敏感。这些细胞的过敏性与apn1突变酵母细胞染色体DNA中未修复损伤的积累有关。过氧化氢处理的APN1+而不是APN1突变细胞在处理后能有效地再生高分子量DNA。在Apn1缺陷突变体中积累的DNA链断裂包含阻止DNA聚合酶作用的损伤，但在体外可以通过纯化的Apn1去除。与甲基甲烷磺酸处理细胞的DNA相似的结果对应于apn1突变细胞中未修复的DNA无嘌呤位点的积累。Apn1突变体酿酒酵母的自发突变率是野生型酵母细胞的6-12倍。这一增加表明，在正常生长条件下，作为Apn1靶标的DNA损伤是大量产生的，如果不修复，这种损伤可能会发生突变。
The APN1 gene of Saccharomyces cerevisiae encodes the major apurinic/apyrimidinic endonuclease and 3'-repair DNA diesterase in yeast cell extracts. The Apn1 protein is a homology of Escherichia coli endonuclease IV, which functions in the repair of some oxidative and alkylation damages in that organism. We show here that yeast strains lacking Apn1 (generated by targeted gene disruption or deletion-replacement) are hypersensitive to both oxidative (hydrogen peroxide and t-butylhdroperoxide) and alkylating (methyl- and ethylmethane sulfonate) agents that damage DNA. These cellular hypersensitivities are correlated with the accumulation of unrepaired damages in the chromosomal DNA of apn1 mutant yeast cells. Hydrogen peroxide-treated APN1+ but not apn1 mutant cells regenerate high-molecular-weight DNA efficiently after the treatment. The DNA strand breaks that accumulate in the Apn1-deficient mutant contain lesions that block the action of DNA polymerase but can be removed in vitro by purified Apn1. An analogous result with DNA from methylmethane sulfonate-treated cells corresponded to the accumulation of unrepaired DNA apurinic sites in the apn1 mutant cells. The rate of spontaneous mutation in apn1 mutant S. cerevisiae was 6- to 12-fold higher than that measured for wild-type yeast cells. This increase indicates that under normal growth conditions, the production of DNA damages that are targets for Apn1 is substantial and that such lesions can be mutagenic when left unrepaired.