Trans-complementation by human apurinic endonuclease (Ape) of hypersensitivity to DNA damage and spontaneous mutator phenotype in apn1-yeast.
Trans-complementation by human apurinic endonuclease (Ape) of hypersensitivity to DNA damage and spontaneous mutator phenotype in apn1-yeast.
复制标题
人无嘌呤核酸内切酶 (Ape) 对 apn1 酵母中 DNA 损伤和自发突变表型过敏的反式互补。
DOI：
10.1093/nar/23.24.5027
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发表时间：
1995
影响因子：
14.9
通讯作者：
Demple,B
中科院分区：
文献类型：
--
作者：
Wilson3rd,DM;Bennett,RA;Marquis,JC;Ansari,P;Demple,B
DNA中的碱基（AP）位点具有潜在的致死性和诱变性。II类AP内切酶启动这些和其他DNA损伤的修复。在酵母中，这种类型的主要酶是Apn1，它的消除使细胞对简单的烷基化剂或氧化剂的杀死敏感，并提高了自发突变率。我们研究了与Apn1结构无关的主要人类II类AP内切酶Ape在体内取代酵母酶的能力。共聚焦免疫显微镜研究表明，酵母中表达的Ape约有25%存在于细胞核中。高水平的Ape表达相当于每个细胞核约7000个分子，相当于正常的Apn1拷贝数，使Apn1缺陷（apn−）酵母对甲基甲烷硫酸盐的抗性恢复到接近野生型的水平。在apn1−中，Ape在酵母中的表达对h2o2胁迫的保护作用很小，这与人类酶的弱3-修复二酯酶活性一致。每核约2000个分子的Ape表达将apn1 -酵母的自发突变率降低到野生型细胞的水平。由于猿具有强大的AP内切酶，但3 ' -二酯酶活性较弱，这些发现表明内源性产生的AP位点可以驱动自发突变。
Abasic (AP) sites in DNA are potentially lethal and mutagenlc. ‘Class II’ AP endonucleases Initiate the repair of these and other DNA lesions. In yeast, the predominant enzyme of this type is Apn1, and its elimination sensitizes the cells to killing by simple alkylatlng agents or oxidants, and raises the rate of spontaneous mutation. We investigated the ability of the major human class II AP endonuclease, Ape, which is structurally unrelated to Apn1, to replace the yeast enzymeIn vivo. Confocal immunomlcroscopy studies indicate that ∼25% of the Ape expressed in yeast is present in the nucleus. High-level Ape expression corresponding to ∼7000 molecules per nucleus, equal to the normal Apn1 copy number, restored resistance to methyl methanesulfonate to near wild-type levels in Apn1-deficient (apn−) yeast. Ape expression in apn1−, yeast provided little protection against H2O2challenges, consistent with the weak 3-repair diesterase activity of the human enzyme. Ape expression at ∼2000 molecules per nucleus reduced the spontaneous mutation rate of apn1−yeast to that seen for wild-type cells. Because Ape has a powerful AP endonuclease but weak 3′-diesterase activity, these findings indicate that endogenously generated AP sites can drive spontaneous mutagenesis.