期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2015
卷号：112
期号：27
页码：8272-8277
DOI：10.1073/pnas.1508509112
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceNucleotide excision repair (NER) is a versatile repair machinery able to protect organisms from DNA damage. Defective NER leads to diseases like xeroderma pigmentosum (XP). XPA is a central NER protein that interacts with DNA in an unknown fashion. Here we present two crystal structures of the yeast homolog of XPA, Rad14, in complex with two NER substrate lesions. Rad14 binds to the damaged DNA from both sides of the lesion. Binding creates a sharp kink of the duplex by 70{degrees}. Each protein inserts a hairpin loop into the duplex to induce partial melting around the lesion. The structures provide insight into the mechanism of how XPA binds to kinked and lesion-containing DNA. Nucleotide excision repair (NER) is responsible for the removal of a large variety of structurally diverse DNA lesions. Mutations of the involved proteins cause the xeroderma pigmentosum (XP) cancer predisposition syndrome. Although the general mechanism of the NER process is well studied, the function of the XPA protein, which is of central importance for successful NER, has remained enigmatic. It is known, that XPA binds kinked DNA structures and that it interacts also with DNA duplexes containing certain lesions, but the mechanism of interactions is unknown. Here we present two crystal structures of the DNA binding domain (DBD) of the yeast XPA homolog Rad14 bound to DNA with either a cisplatin lesion (1,2-GG) or an acetylaminofluorene adduct (AAF-dG). In the structures, we see that two Rad14 molecules bind to the duplex, which induces DNA melting of the duplex remote from the lesion. Each monomer interrogates the duplex with a {beta}-hairpin, which creates a 13mer duplex recognition motif additionally characterized by a sharp 70{degrees} DNA kink at the position of the lesion. Although the 1,2-GG lesion stabilizes the kink due to the covalent fixation of the crosslinked dG bases at a 90{degrees} angle, the AAF-dG fully intercalates into the duplex to stabilize the kinked structure.
