Fission yeast Scm3 mediates stable assembly of Cnp1/CENP-A into centromeric chromatin.
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.
Williams
Jessica S
JS
Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 90237, USA.
Hayashi
Takeshi
T
Yanagida
Mitsuhiro
M
Russell
Paul
P
D002352:Carrier Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D002503:Centromere / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000032:analysis / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D008938:Mitosis; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*
D002352:Carrier Proteins; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; C410349:Cnp1 protein, S pombe; D006657:Histones; C539322:Mis16 protein, S pombe; C539323:Mis18 protein, S pombe; D029702:Schizosaccharomyces pombe Proteins; C539321:Scm3 protein, S pombe