Requirement for Phe36 for DNA binding and mismatch repair by Escherichia coli MutS protein.
Requirement for Phe36 for DNA binding and mismatch repair by Escherichia coli MutS protein.
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大肠杆菌 MutS 蛋白 DNA 结合和错配修复需要 Phe36。
DOI：
10.1093/nar/28.18.3564
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发表时间：
2000
影响因子：
14.9
通讯作者：
Hsieh,P
中科院分区：
文献类型：
--
作者：
Yamamoto,A;Schofield,MJ;Biswas,I;Hsieh,P
DNA 修复蛋白 MutS 家族可识别碱基对错配和插入/缺失错配，并以链特异性方式靶向它们进行修复。光交联和突变研究先前在水生栖热菌 MutS 蛋白的 N 末端发现了一个高度保守的 Phe 残基，该残基对于体外错配识别至关重要。此处，对相应 Phe36 残基被 Ala 取代的突变型大肠杆菌 MutS 蛋白进行了体内错配修复以及体外 DNA 结合和 ATP 水解能力的评估。根据利福平突变或 inlacZ 特定点突变的回复判断，F36A 蛋白无法恢复 amutSstrain 的错配修复能力。 F36A 蛋白也严重缺乏与含有未配对胸苷或 G:T 错配的异源双链体的结合，尽管其内在 ATP 酶活性和亚基寡聚化与野生型 MutS 蛋白非常相似。因此，F36A突变似乎赋予了识别插入/缺失和碱基对错配的特异性缺陷。
The MutS family of DNA repair proteins recognizes base pair mismatches and insertion/deletion mismatches and targets them for repair in a strand-specific manner. Photocrosslinking and mutational studies previously identified a highly conserved Phe residue at the N-terminus ofThermus aquaticusMutS protein that is critical for mismatch recognitionin vitro. Here, a mutantEscherichia coliMutS protein harboring a substitution of Ala for the corresponding Phe36 residue is assessed for proficiency in mismatch repairin vivoand DNA binding and ATP hydrolysisin vitro. The F36A protein is unable to restore mismatch repair proficiency to amutSstrain as judged by mutation to rifampicin or reversion of a specific point mutation inlacZ. The F36A protein is also severely deficient for binding to heteroduplexes containing an unpaired thymidine or a G:T mismatch although its intrinsic ATPase activity and subunit oligomerization are very similar to that of the wild-type MutS protein. Thus, the F36A mutation appears to confer a defect specific for recognition of insertion/deletion and base pair mismatches.