5b24
From Proteopedia
The crystal structure of the nucleosome containing cyclobutane pyrimidine dimer
Structural highlights
Function[H2B1J_HUMAN] Core component of nucleosome. Nucleosomes wrap and compact DNA into chromatin, limiting DNA accessibility to the cellular machineries which require DNA as a template. Histones thereby play a central role in transcription regulation, DNA repair, DNA replication and chromosomal stability. DNA accessibility is regulated via a complex set of post-translational modifications of histones, also called histone code, and nucleosome remodeling.[1] [2] [3] Has broad antibacterial activity. May contribute to the formation of the functional antimicrobial barrier of the colonic epithelium, and to the bactericidal activity of amniotic fluid.[4] [5] [6] Publication Abstract from PubMedThe cyclobutane pyrimidine dimer (CPD) is induced in genomic DNA by ultraviolet (UV) light. In mammals, this photolesion is primarily induced within nucleosomal DNA, and repaired exclusively by the nucleotide excision repair (NER) pathway. However, the mechanism by which the CPD is accommodated within the nucleosome has remained unknown. We now report the crystal structure of a nucleosome containing CPDs. In the nucleosome, the CPD induces only limited local backbone distortion, and the affected bases are accommodated within the duplex. Interestingly, one of the affected thymine bases is located within 3.0 A from the undamaged complementary adenine base, suggesting the formation of complementary hydrogen bonds in the nucleosome. We also found that UV-DDB, which binds the CPD at the initial stage of the NER pathway, also efficiently binds to the nucleosomal CPD. These results provide important structural and biochemical information for understanding how the CPD is accommodated and recognized in chromatin. Crystal structure of the nucleosome containing ultraviolet light-induced cyclobutane pyrimidine dimer.,Horikoshi N, Tachiwana H, Kagawa W, Osakabe A, Matsumoto S, Iwai S, Sugasawa K, Kurumizaka H Biochem Biophys Res Commun. 2016 Feb 26;471(1):117-22. doi:, 10.1016/j.bbrc.2016.01.170. Epub 2016 Feb 2. PMID:26837048[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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