3an2
From Proteopedia
The structure of the centromeric nucleosome containing CENP-A
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] [CENPA_HUMAN] Histone H3-like variant which exclusively replaces conventional H3 in the nucleosome core of centromeric chromatin at the inner plate of the kinetochore. Required for recruitment and assembly of kinetochore proteins, mitotic progression and chromosome segregation. May serve as an epigenetic mark that propagates centromere identity through replication and cell division. The CENPA-H4 heterotetramer can bind DNA by itself (in vitro).[7] [8] [B2R4R0_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.[RuleBase:RU000528][SAAS:SAAS00108761] Publication Abstract from PubMedIn eukaryotes, accurate chromosome segregation during mitosis and meiosis is coordinated by kinetochores, which are unique chromosomal sites for microtubule attachment. Centromeres specify the kinetochore formation sites on individual chromosomes, and are epigenetically marked by the assembly of nucleosomes containing the centromere-specific histone H3 variant, CENP-A. Although the underlying mechanism is unclear, centromere inheritance is probably dictated by the architecture of the centromeric nucleosome. Here we report the crystal structure of the human centromeric nucleosome containing CENP-A and its cognate alpha-satellite DNA derivative (147 base pairs). In the human CENP-A nucleosome, the DNA is wrapped around the histone octamer, consisting of two each of histones H2A, H2B, H4 and CENP-A, in a left-handed orientation. However, unlike the canonical H3 nucleosome, only the central 121 base pairs of the DNA are visible. The thirteen base pairs from both ends of the DNA are invisible in the crystal structure, and the alphaN helix of CENP-A is shorter than that of H3, which is known to be important for the orientation of the DNA ends in the canonical H3 nucleosome. A structural comparison of the CENP-A and H3 nucleosomes revealed that CENP-A contains two extra amino acid residues (Arg 80 and Gly 81) in the loop 1 region, which is completely exposed to the solvent. Mutations of the CENP-A loop 1 residues reduced CENP-A retention at the centromeres in human cells. Therefore, the CENP-A loop 1 may function in stabilizing the centromeric chromatin containing CENP-A, possibly by providing a binding site for trans-acting factors. The structure provides the first atomic-resolution picture of the centromere-specific nucleosome. Crystal structure of the human centromeric nucleosome containing CENP-A.,Tachiwana H, Kagawa W, Shiga T, Osakabe A, Miya Y, Saito K, Hayashi-Takanaka Y, Oda T, Sato M, Park SY, Kimura H, Kurumizaka H Nature. 2011 Jul 10. doi: 10.1038/nature10258. PMID:21743476[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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