Assembly of Drosophila centromeric nucleosomes requires CID dimerization.
Centromeres are essential chromosomal regions required for kinetochore assembly and chromosome segregation. The composition and organization of centromeric nucleosomes containing the essential histone H3 variant CENP-A (CID in Drosophila) is a fundamental, unresolved issue. Using immunoprecipitation of CID mononucleosomes and cysteine crosslinking, we demonstrate that centromeric nucleosomes contain CID dimers in vivo. Furthermore, CID dimerization and centromeric targeting require a residue implicated in formation of the four-helix bundle, which mediates intranucleosomal H3 dimerization and nucleosome integrity. Taken together, our findings suggest that CID nucleosomes are octameric in vivo and that CID dimerization is essential for correct centromere assembly.
Department of Genome Dynamics, Lawrence Berkeley National Laboratory, University of California, Berkeley, Berkeley, CA 94720, USA.
Weiguo
W
Zhang
Serafin U
SU
Colmenares
Gary H
GH
Karpen
D000818:Animals; D002503:Centromere / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000076247:Centromere Protein A; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics*; D006657:Histones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008957:Models, Genetic; D008958:Models, Molecular; D009707:Nucleosomes / Q000737:chemistry / Q000378:metabolism*; D014461:Ultracentrifugation / Q000379:methods
D000076247:Centromere Protein A; C427237:Cid protein, Drosophila; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D006657:Histones; D009707:Nucleosomes