5gxq
From Proteopedia
The crystal structure of the nucleosome containing H3.6
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 PubMedNon-allelic histone variants are considered as epigenetic factors that regulate genomic DNA functions in eukaryotic chromosomes. In this study, we identified three new human histone H3 variants (named H3.6, H3.7, and H3.8), which were previously annotated as pseudogenes. H3.6 and H3.8 conserve the H3.3-specific amino acid residues, but H3.7 shares the specific amino acid residues with H3.1. We successfully reconstituted the nucleosome containing H3.6 in vitro and determined its crystal structure. In the H3.6 nucleosome, the H3.6-specific Val62 residue hydrophobically contacts the cognate H4 molecule, but its contact area is smaller than that of the corresponding H3.3 Ile62 residue. The thermal stability assay revealed that the H3.6 nucleosome is substantially unstable, as compared to the H3.3 nucleosome. Interestingly, mutational analysis demonstrated that the H3.6 Val62 residue is fully responsible for the H3.6 nucleosome instability, probably because of the weakened hydrophobic interaction with H4. We also reconstituted the nucleosome containing H3.8, but its thermal stability was quite low. In contrast, purified H3.7 failed to form nucleosomes in vitro. The identification and characterization of these novel human histone H3 variants provide important new insights into understanding the epigenetic regulation of the human genome. Crystal Structure and Characterization of Novel Human Histone H3 Variants, H3.6, H3.7, and H3.8.,Taguchi H, Xie Y, Horikoshi N, Maehara K, Harada A, Nogami J, Sato K, Arimura Y, Osakabe A, Kujirai T, Iwasaki T, Semba Y, Tachibana T, Kimura H, Ohkawa Y, Kurumizaka H Biochemistry. 2017 Apr 10. doi: 10.1021/acs.biochem.6b01098. PMID:28374988[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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