The Saccharomyces cerevisiae ETH1 gene, an inducible homolog of exonuclease III that provides resistance to DNA-damaging agents and limits spontaneous mutagenesis.
The Saccharomyces cerevisiae ETH1 gene, an inducible homolog of exonuclease III that provides resistance to DNA-damaging agents and limits spontaneous mutagenesis.
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酿酒酵母 ETH1 基因是核酸外切酶 III 的诱导型同源物，可提供对 DNA 损伤剂的抵抗力并限制自发突变。
DOI：
10.1128/mcb.19.3.1800
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发表时间：
1999
影响因子：
5.3
通讯作者：
Bennett,RA
中科院分区：
文献类型：
--
作者：
Bennett,RA
最近测序的酿酒酵母基因组被搜索到一个与编码人类主要AP内切酶的基因同源的基因，该酶是高度保守的DNA碱基切除修复途径的组成部分。发现一个开放阅读框编码一个可能的蛋白(与裂殖酵母eth1+[开放阅读框SPBC3D6.10]基因产物有34%的同源性)，其347个残基片段与核酸外切酶III家族的AP内切酶同源。经烷化剂甲基甲烷磺酸(MMS)处理后，野生型细胞中ETH1mRNA的合成是未处理细胞的6倍。为了研究ETH1的功能，对一株野生型菌株和一株APN1编码的已知酵母AP内切酶缺陷菌株的开放阅读框进行了缺失。∼菌株对MMS、H_2O_2或Ph_1不敏感，而Apn_1菌株对M MS的敏感性是野生型的3倍，∼对H_2O_2的敏感性是野生型的10倍。双突变株(Apn1eth1)对∼和∼的敏感度分别是apn1和apn1的15倍和2-3倍。与野生型相比，消除apn1中的ETH1菌株的自发突变率也增加了9倍或31倍，这分别是通过回复到腺嘌呤或赖氨酸原生体来确定的。用含ETH1的表达载体转化apn1细胞，可逆转其对MMS的超敏反应，并限制其自发诱变率。ETH1在Adut-1xthA3大肠杆菌中的表达表明，该基因产物在功能上补充了缺失的AP内切酶活性。因此，在缺乏主要AP内切酶活性的apn1细胞中，ETH1为自发或诱导的DNA损伤提供了另一种修复能力，通常由Apn1蛋白修复。
The recently sequencedSaccharomyces cerevisiaegenome was searched for a gene with homology to the gene encoding the major human AP endonuclease, a component of the highly conserved DNA base excision repair pathway. An open reading frame was found to encode a putative protein (34% identical to theSchizosaccharomyces pombe eth1+[open reading frame SPBC3D6.10] gene product) with a 347-residue segment homologous to the exonuclease III family of AP endonucleases. Synthesis of mRNA fromETH1in wild-type cells was induced sixfold relative to that in untreated cells after exposure to the alkylating agent methyl methanesulfonate (MMS). To investigate the function ofETH1, deletions of the open reading frame were made in a wild-type strain and a strain deficient in the known yeast AP endonuclease encoded byAPN1. eth1strains were not more sensitive to killing by MMS, hydrogen peroxide, or phleomycin D1, whereasapn1strains were ∼3-fold more sensitive to MMS and ∼10-fold more sensitive to hydrogen peroxide than was the wild type. Double-mutant strains (apn1 eth1) were ∼15-fold more sensitive to MMS and ∼2- to 3-fold more sensitive to hydrogen peroxide and phleomycin D1 than wereapn1strains. Elimination ofETH1inapn1strains also increased spontaneous mutation rates 9- or 31-fold compared to the wild type as determined by reversion to adenine or lysine prototrophy, respectively. Transformation ofapn1 eth1cells with an expression vector containingETH1reversed the hypersensitivity to MMS and limited the rate of spontaneous mutagenesis. Expression ofETH1in adut-1 xthA3 Escherichia colistrain demonstrated that the gene product functionally complements the missing AP endonuclease activity. Thus, inapn1cells where the major AP endonuclease activity is missing,ETH1offers an alternate capacity for repair of spontaneous or induced damage to DNA that is normally repaired by Apn1 protein.