Urahama Takashi, Horikoshi Naoki, Osakabe Akihisa, Tachiwana Hiroaki, Kurumizaka Hitoshi
Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan.
Acta Crystallogr F Struct Biol Commun. 2014 Apr;70(Pt 4):444-9. doi: 10.1107/S2053230X14004695. Epub 2014 Mar 25.
The 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 Å 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.
人类组蛋白H2B变体TSH2B在睾丸中高度表达，可能在精子发生过程中的染色质转变中发挥作用。在本研究中，以2.8 Å的分辨率确定了包含TSH2B的人类睾丸特异性核小体的晶体结构。在TSH2B特异性氨基酸残基Ser85周围检测到核小体中TSH2B与经典H2B之间的局部结构差异。TSH2B的Ser85残基在核小体中不与H4相互作用，但在经典核小体中，H2B的Asn84残基（对应于TSH2B的Ser85残基）与H4的Arg78残基形成水介导的氢键。相比之下，其他TSH2B特异性氨基酸残基在TSH2B核小体中未引起任何明显的局部结构变化。这些发现可能为理解睾丸特异性组蛋白变体在精子发生过程中如何形成核小体提供重要信息。
