The spacer region of XPG mediates recruitment to nucleotide excision repair complexes and determines substrate specificity
The spacer region of XPG mediates recruitment to nucleotide excision repair complexes and determines substrate specificity
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DOI：
10.1074/jbc.m412228200
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发表时间：
2005-02-25
影响因子：
4.8
通讯作者：
Schärer, OD
中科院分区：
文献类型：
--
作者：
Dunand-Sauthier, I;Hohl, M;Schärer, OD
XPG在核苷酸切除修复（NER）中具有结构和催化作用，并且属于结构特异性核酸酶的FEN-1家族。XPG含有一段超过600个氨基酸的序列，称为保守的N-和I-核酸酶区域之间的"间隔区"。它的作用是未知的，它不类似于任何已知的蛋白质。为了研究其可能的功能，我们产生并分析了几个XPG的缺失突变体。间隔区不是核酸内切酶活性所必需的，但氨基酸111 - 550有助于XPG的底物特异性，并且它们是与TFIIH相互作用以及体外和体内NER活性所必需的。残基184 - 210和554 - 730的缺失仅导致NER活性的部分缺陷和与TFIIH的减弱的相互作用。通过免疫荧光在活细胞中的局部UV损伤位点未观察到XPG Δ 184 - 210和XPG Δ 554 - 730，表明XPG和TFIIH之间的相互作用减弱导致NER反应动力学改变。这项研究表明，间隔区的N-末端部分通过介导XPG-TFIIH相互作用和XPG底物特异性对NTER进展特别重要。
XPG has structural and catalytic roles in nucleotide excision repair (NER) and belongs to the FEN-1 family of structure-specific nucleases. XPG contains a stretch of over 600 amino acids termed the "spacer region" between the conserved N- and I-nuclease regions. Its role is unknown, and it is not similar to any known protein. To investigate its possible functions, we generated and analyzed several deletion mutants of XPG. The spacer region is not required for endonuclease activity, but amino acids 111-550 contribute to the substrate specificity of XPG, and they are required for interaction with TFIIH and for NER activity in vitro and in vivo. Deletion of residues 184-210 and 554-730 leads only to a partial defect in NER activity and a weakened interaction with TFIIH. XPGDelta184-210 and XPGDelta554-730 are not observed at sites of local UV damage in living cells by immunofluoreseence, suggesting that the weakened interaction between XPG and TFIIH results in an NER reaction with altered kinetics. This study demonstrates that the N-terminal portion of the spacer region is particularly important for NTER progression by mediating the XPG-TFIIH interaction and XPG substrate specificity.