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SIRT6 bound to an H3K9Ac nucleosomeSIRT6 bound to an H3K9Ac nucleosome
Structural highlights
FunctionH32_XENLA 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. Publication Abstract from PubMedThe reversible acetylation of histone lysine residues is controlled by the action of acetyltransferases and deacetylases (HDACs), which regulate chromatin structure and gene expression. The sirtuins are a family of NAD-dependent HDAC enzymes, and one member, sirtuin 6 (Sirt6), influences DNA repair, transcription, and aging. Here, we demonstrate that Sirt6 is efficient at deacetylating several histone H3 acetylation sites, including its canonical site Lys9, in the context of nucleosomes but not free acetylated histone H3 protein substrates. By installing a chemical warhead at the Lys9 position of histone H3, we trap a catalytically poised Sirt6 in complex with a nucleosome and employ this in cryo-EM structural analysis. The structure of Sirt6 bound to a nucleosome reveals extensive interactions between distinct segments of Sirt6 and the H2A/H2B acidic patch and nucleosomal DNA, which accounts for the rapid deacetylation of nucleosomal H3 sites and the disfavoring of histone H2B acetylation sites. These findings provide a new framework for understanding how HDACs target and regulate chromatin. Structural Basis of Sirtuin 6-Catalyzed Nucleosome Deacetylation.,Wang ZA, Markert JW, Whedon SD, Yapa Abeywardana M, Lee K, Jiang H, Suarez C, Lin H, Farnung L, Cole PA J Am Chem Soc. 2023 Mar 29;145(12):6811-6822. doi: 10.1021/jacs.2c13512. Epub , 2023 Mar 17. PMID:36930461[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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