Recognition of helical kinks by xeroderma pigmentosum group A protein triggers DNA excision repair
Recognition of helical kinks by xeroderma pigmentosum group A protein triggers DNA excision repair
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DOI：
10.1038/nsmb1061
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发表时间：
2006-03-01
影响因子：
16.8
通讯作者：
Naegeli, H
中科院分区：
文献类型：
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作者：
Camenisch, U;Dip, R;Naegeli, H
人XPA蛋白是核苷酸切除修复途径的关键亚基，其功能已通过在其推定的DNA结合裂缝中进行定点取代进行了研究。在宿主细胞再活化试验中筛选修复活性后，我们通过比较它们对不同底物结构的亲和力（包括为扭曲的反应中间体提供替代的DNA连接）以及通过测试它们招募下游核酸内切酶伴侣的能力来分析突变体。当XPA突变仅消除与线性DNA分子的简单相互作用时，正常的修复能力得以保留。相比之下，来自K141E和K179E双突变体的结果显示，切除关键取决于XPA蛋白在DNA底物中具有尖锐弯曲角的组装。这些发现显示了受损位点的变形性增加，导致XPA识别的螺旋扭结，有助于DNA修复中的靶选择性。
The function of human XPA protein, a key subunit of the nucleotide excision repair pathway, has been examined with site-directed substitutions in its putative DNA-binding cleft. After screening for repair activity in a host-cell reactivation assay, we analyzed mutants by comparing their affinities for different substrate architectures, including DNA junctions that provide a surrogate for distorted reaction intermediates, and by testing their ability to recruit the downstream endonuclease partner. Normal repair proficiency was retained when XPA mutations abolished only the simple interaction with linear DNA molecules. By contrast, results from a K141E K179E double mutant revealed that excision is crucially dependent on the assembly of XPA protein with a sharp bending angle in the DNA substrate. These findings show how an increased deformability of damaged sites, leading to helical kinks recognized by XPA, contributes to target selectivity in DNA repair.