ATP-dependent chromatin remodeling facilitates nucleotide excision repair of UV-induced DNA lesions in synthetic dinucleosomes |
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Authors: | Ura K Araki M Saeki H Masutani C Ito T Iwai S Mizukoshi T Kaneda Y Hanaoka F |
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Institution: | Division of Gene Therapy Science, Osaka University School of Medicine, 2-2 Yamada-oka, Suita, Japan. kiyoeura@gts.med.osaka-u.ac.jp |
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Abstract: | To investigate the relationship between chromatin dynamics and nucleotide excision repair (NER), we have examined the effect of chromatin structure on the formation of two major classes of UV-induced DNA lesions in reconstituted dinucleosomes. Furthermore, we have developed a model chromatin-NER system consisting of purified human NER factors and dinucleosome substrates that contain pyrimidine (6-4) pyrimidone photoproducts (6-4PPs) either at the center of the nucleosome or in the linker DNA. We have found that the two classes of UV-induced DNA lesions are formed efficiently at every location on dinucleosomes in a manner similar to that of naked DNA, even in the presence of histone H1. On the other hand, excision of 6-4PPs is strongly inhibited by dinucleosome assembly, even within the linker DNA region. These results provide direct evidence that the human NER machinery requires a space greater than the size of the linker DNA to excise UV lesions efficiently. Interestingly, NER dual incision in dinucleosomes is facilitated by recombinant ACF, an ATP-dependent chromatin remodeling factor. Our results indicate that there is a functional connection between chromatin remodeling and the initiation step of NER. |
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