Three-dimensional localization of CENP-A suggests a complex higher order structure of centromeric chromatin.
The histone H3 variant centromere protein A (CENP-A) is central to centromere formation throughout eukaryotes. A long-standing question in centromere biology has been the organization of CENP-A at the centromere and its implications for the structure of centromeric chromatin. In this study, we describe the three-dimensional localization of CENP-A at the inner kinetochore plate through serial-section transmission electron microscopy of human mitotic chromosomes. At the kinetochores of normal centromeres and at a neocentromere, CENP-A occupies a compact domain at the inner kinetochore plate, stretching across two thirds of the length of the constriction but encompassing only one third of the constriction width and height. Within this domain, evidence of substructure is apparent. Combined with previous chromatin immunoprecipitation results (Saffery, R., H. Sumer, S. Hassan, L.H. Wong, J.M. Craig, K. Todokoro, M. Anderson, A. Stafford, and K.H.A. Choo. 2003. Mol. Cell. 12:509-516; Chueh, A.C., L.H. Wong, N. Wong, and K.H.A. Choo. 2005. Hum. Mol. Genet. 14:85-93), our data suggest that centromeric chromatin is arranged in a coiled 30-nm fiber that is itself coiled or folded to form a higher order structure.
Marshall
Owen J
OJ
Chromosome and Chromatin Research, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria 3052, Australia.
Marshall
Alan T
AT
Choo
K H Andy
KH
D001324:Autoantigens / Q000032:analysis* / Q000378:metabolism; D001665:Binding Sites; D002478:Cells, Cultured; D002503:Centromere / Q000378:metabolism / Q000648:ultrastructure*; D000076247:Centromere Protein A; D002843:Chromatin / Q000378:metabolism / Q000648:ultrastructure*; D002868:Chromosomal Proteins, Non-Histone / Q000032:analysis* / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D018386:Kinetochores / Q000378:metabolism; D008954:Models, Biological; D017434:Protein Structure, Tertiary
D001324:Autoantigens; C000619700:CENPA protein, human; D000076247:Centromere Protein A; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone