裂殖酵母Scm3介导Cnp1/CENP-A稳定组装到着丝粒染色质中。
Fission yeast Scm3 mediates stable assembly of Cnp1/CENP-A into centromeric chromatin.
作者信息
Williams Jessica S, Hayashi Takeshi, Yanagida Mitsuhiro, Russell Paul
机构信息
Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 90237, USA.
出版信息
Mol Cell. 2009 Feb 13;33(3):287-98. doi: 10.1016/j.molcel.2009.01.017.
Mis16 and Mis18 are subunits of a protein complex required for incorporation of the histone H3 variant CenH3 (Cnp1/CENP-A) into centromeric chromatin in Schizosaccharomyces pombe and mammals. How the Mis16-Mis18 complex performs this function is unknown. Here, we report that the Mis16-Mis18 complex is required for centromere localization of Scm3(Sp), a Cnp1-binding protein related to Saccharomyces cerevisiae Scm3. Scm3(Sp) is required for centromeric localization of Cnp1, while Scm3(Sp) localizes at centromeres independently of Cnp1. Like the Mis16-Mis18 complex but unlike Cnp1, Scm3(Sp) dissociates from centromeres during mitosis. Inactivation of Scm3(Sp) or Mis18 increases centromere localization of histones H3 and H2A/H2B, which are largely absent from centromeres in wild-type cells. Whereas S. cerevisiae Scm3 is proposed to replace histone H2A/H2B in centromeric nucleosomes, the dynamic behavior of S. pombe Scm3 suggests that it acts as a Cnp1 assembly/maintenance factor that directly mediates the stable deposition of Cnp1 into centromeric chromatin.
Mis16和Mis18是一种蛋白质复合物的亚基，该复合物是粟酒裂殖酵母和哺乳动物着丝粒染色质中组蛋白H3变体CenH3（Cnp1/CENP-A）整合所必需的。Mis16-Mis18复合物如何执行这一功能尚不清楚。在此，我们报告Mis16-Mis18复合物是Scm3（Sp）着丝粒定位所必需的，Scm3（Sp）是一种与酿酒酵母Scm3相关的Cnp1结合蛋白。Scm3（Sp）是Cnp1着丝粒定位所必需的，而Scm3（Sp）独立于Cnp1定位于着丝粒。与Mis16-Mis18复合物一样但与Cnp1不同，Scm3（Sp）在有丝分裂期间从着丝粒解离。Scm3（Sp）或Mis18的失活增加了组蛋白H3和H2A/H2B的着丝粒定位，而在野生型细胞的着丝粒中这些组蛋白基本不存在。虽然有人提出酿酒酵母Scm3在着丝粒核小体中取代组蛋白H2A/H2B，但粟酒裂殖酵母Scm3的动态行为表明它作为一种Cnp1组装/维持因子，直接介导Cnp1稳定沉积到着丝粒染色质中。
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