3wkj
From Proteopedia
The nucleosome containing human TSH2B
Structural highlights
Function[H2B1A_HUMAN] Variant histone specifically required to direct the transformation of dissociating nucleosomes to protamine in male germ cells. Entirely replaces classical histone H2B prior nucleosome to protamine transition and probably acts as a nucleosome dissociating factor that creates a more dynamic chromatin, facilitating the large-scale exchange of histones. Also expressed maternally and is present in the female pronucleus, suggesting a similar role in protamine replacement by nucleosomes at fertilization (By similarity). Also found in fat cells, its function and the presence of post-translational modifications specific to such cells are still unclear. 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] Publication Abstract from PubMedThe human histone H2B variant TSH2B is highly expressed in testis and may function in the chromatin transition during spermatogenesis. In the present study, the crystal structure of the human testis-specific nucleosome containing TSH2B was determined at 2.8 A resolution. A local structural difference between TSH2B and canonical H2B in nucleosomes was detected around the TSH2B-specific amino-acid residue Ser85. The TSH2B Ser85 residue does not interact with H4 in the nucleosome, but in the canonical nucleosome the H2B Asn84 residue (corresponding to the TSH2B Ser85 residue) forms water-mediated hydrogen bonds with the H4 Arg78 residue. In contrast, the other TSH2B-specific amino-acid residues did not induce any significant local structural changes in the TSH2B nucleosome. These findings may provide important information for understanding how testis-specific histone variants form nucleosomes during spermatogenesis. Structure of human nucleosome containing the testis-specific histone variant TSH2B.,Urahama T, Horikoshi N, Osakabe A, Tachiwana H, Kurumizaka H Acta Crystallogr F Struct Biol Commun. 2014 Apr;70(Pt 4):444-9. doi:, 10.1107/S2053230X14004695. Epub 2014 Mar 25. PMID:24699735[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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