Fission Yeast Scm3 Mediates Stable Assembly of Cnp1/CENP-A into Centromeric Chromatin

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• 作者：Jessica S. Williams ; Takeshi Hayashi ; Mitsuhiro Yanagida ; Paul Russell
• 刊名：Molecular Cell
• 出版年：2009
• 出版时间：13 February 2009
• 年：2009
• 卷：33
• 期：3
• 页码：287-298
• 全文大小：1503 K

文摘

Summary

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.