In Vivo Destabilization and Functional Defects of the Xeroderma Pigmentosum C Protein Caused by a Pathogenic Missense Mutation
In Vivo Destabilization and Functional Defects of the Xeroderma Pigmentosum C Protein Caused by a Pathogenic Missense Mutation
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DOI：
10.1128/mcb.02166-06
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发表时间：
2007-08
影响因子：
5.3
通讯作者：
Gentaro Yasuda;Ryotaro Nishi;Eriko Watanabe;Toshio Mori;S. Iwai;D. Orioli;M. Stefanini;F. Hanaoka;K. Sugasawa
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文献类型：
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作者：
Gentaro Yasuda;Ryotaro Nishi;Eriko Watanabe;Toshio Mori;S. Iwai;D. Orioli;M. Stefanini;F. Hanaoka;K. Sugasawa
着色性干皮病C组（XPC）蛋白在哺乳动物全基因组核苷酸切除修复（NER）中的DNA损伤识别中起重要作用。在这里，我们分析了NER失活的功能基础所造成的一个单一的氨基酸取代（色氨酸丝氨酸在位置690）在XPC，以前确定在XPC患者XP 13 PV。Trp 690 Ser的变化显著影响XPC蛋白的体内稳定性，从而导致其在XP 13 PV成纤维细胞中的稳态水平显著降低。尽管正常的异源三聚体复合物的形成和与其他NER因子的物理相互作用，突变XPC蛋白缺乏对未受损和受损DNA的结合亲和力。因此，这种单一氨基酸取代足以通过蛋白质的定量和定性改变损害XPC功能。虽然突变体XPC不能识别受损的DNA，但它仍然能够以紫外线损伤的DNA结合蛋白（UV-DDB）依赖的方式积累到紫外线损伤的亚核结构域。然而，NER因子转录因子IIH和XPA未能与突变体XPC稳定共定位。除了强调UV-DDB在将XPC募集到UV损伤位点中的重要性外，这些发现还证明了XPC在随后的NER中间复合物组装中的DNA结合作用。
ABSTRACT Xeroderma pigmentosum group C (XPC) protein plays an essential role in DNA damage recognition in mammalian global genome nucleotide excision repair (NER). Here, we analyze the functional basis of NER inactivation caused by a single amino acid substitution (Trp to Ser at position 690) in XPC, previously identified in the XPC patient XP13PV. The Trp690Ser change dramatically affects the in vivo stability of the XPC protein, thereby causing a significant reduction of its steady-state level in XP13PV fibroblasts. Despite normal heterotrimeric complex formation and physical interactions with other NER factors, the mutant XPC protein lacks binding affinity for both undamaged and damaged DNA. Thus, this single amino acid substitution is sufficient to compromise XPC function through both quantitative and qualitative alterations of the protein. Although the mutant XPC fails to recognize damaged DNA, it is still capable of accumulating in a UV-damaged DNA-binding protein (UV-DDB)-dependent manner to UV-damaged subnuclear domains. However, the NER factors transcription factor IIH and XPA failed to colocalize stably with the mutant XPC. As well as highlighting the importance of UV-DDB in recruiting XPC to UV-damaged sites, these findings demonstrate the role of DNA binding by XPC in the assembly of subsequent NER intermediate complexes.