title: Structure and Scm3-mediated assembly of budding yeast centromeric nucleosomes.
abstract: Much controversy exists regarding the structural organization of the yeast centromeric nucleosome and the role of the nonhistone protein, Scm3, in its assembly and architecture. Here we show that the substitution of H3 with its centromeric variant Cse4 results in octameric nucleosomes that organize DNA in a left-handed superhelix. We demonstrate by single-molecule approaches, micrococcal nuclease digestion and small-angle X-ray scattering that Cse4-nucleosomes exhibit an open conformation with weakly bound terminal DNA segments. The Cse4-octamer does not preferentially form nucleosomes on its cognate centromeric DNA. We show that Scm3 functions as a Cse4-specific nucleosome assembly factor, and that the resulting octameric nucleosomes do not contain Scm3 as a stably bound component. Taken together, our data provide insights into the assembly and structural features of the budding yeast centromeric nucleosome.
authors.affiliation: Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, USA.
authors.forename: Mekonnen Lemma
authors.initials: ML
authors.lastname: Dechassa
authors.forename: Katharina
authors.initials: K
authors.lastname: Wyns
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.forename: Michael A
authors.initials: MA
authors.lastname: Hall
authors.forename: Michelle D
authors.initials: MD
authors.lastname: Wang
authors.forename: Karolin
authors.initials: K
authors.lastname: Luger
mesh_terms: D002503:Centromere / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D009707:Nucleosomes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C092746:CSE4 protein, S cerevisiae; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D009707:Nucleosomes; D029701:Saccharomyces cerevisiae Proteins; C521684:Scm3 protein, S cerevisiae