Koyama Masako, Nagakura Wataru, Tanaka Hiroki, Kujirai Tomoya, Chikashige Yuji, Haraguchi Tokuko, Hiraoka Yasushi, 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.
Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan.
Biochem Biophys Res Commun. 2017 Jan 22;482(4):896-901. doi: 10.1016/j.bbrc.2016.11.130. Epub 2016 Nov 24.
Schizosaccharomyces pombe, which has a small genome but shares many physiological functions with higher eukaryotes, is a useful single-cell, model eukaryotic organism. In particular, many features concerning chromatin structure and dynamics, including heterochromatin, centromeres, telomeres, and DNA replication origins, are well conserved between S. pombe and higher eukaryotes. However, the S. pombe nucleosome, the fundamental structural unit of chromatin, has not been reconstituted in vitro. In the present study, we established the method to purify S. pombe histones H2A, H2B, H3, and H4, and successfully reconstituted the S. pombe nucleosome in vitro. Our thermal stability assay and micrococcal nuclease treatment assay revealed that the S. pombe nucleosome is markedly unstable and its DNA ends are quite accessible, as compared to the canonical human nucleosome. These findings are important to understand the mechanisms of epigenetic genomic DNA regulation in fission yeast.
粟酒裂殖酵母基因组较小，但与高等真核生物具有许多共同的生理功能，是一种有用的单细胞模式真核生物。特别是，许多与染色质结构和动力学相关的特征，包括异染色质、着丝粒、端粒和DNA复制起点，在粟酒裂殖酵母和高等真核生物之间高度保守。然而，染色质的基本结构单元——粟酒裂殖酵母核小体尚未在体外重建。在本研究中，我们建立了纯化粟酒裂殖酵母组蛋白H2A、H2B、H3和H4的方法，并成功在体外重建了粟酒裂殖酵母核小体。我们的热稳定性测定和微球菌核酸酶处理测定表明，与典型的人类核小体相比，粟酒裂殖酵母核小体明显不稳定，其DNA末端相当容易接近。这些发现对于理解裂殖酵母中表观遗传基因组DNA调控机制具有重要意义。
