Fission yeast Scm3 mediates stable assembly of Cnp1/CENP-A into centromeric chromatin

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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Carrier Proteins / analysis
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Centromere / metabolism*
  • Chromatin / metabolism*
  • Chromosomal Proteins, Non-Histone / analysis
  • Chromosomal Proteins, Non-Histone / metabolism*
  • Histones / metabolism
  • Mitosis
  • Schizosaccharomyces / genetics
  • Schizosaccharomyces / metabolism
  • Schizosaccharomyces pombe Proteins / analysis
  • Schizosaccharomyces pombe Proteins / genetics
  • Schizosaccharomyces pombe Proteins / metabolism*


  • Carrier Proteins
  • Chromatin
  • Chromosomal Proteins, Non-Histone
  • Cnp1 protein, S pombe
  • Histones
  • Mis16 protein, S pombe
  • Mis18 protein, S pombe
  • Schizosaccharomyces pombe Proteins
  • Scm3 protein, S pombe