The mammalian centromere: structural domains and the attenuation of chromatin modeling.
The centromere-kinetochore complex can be divided into distinct domains based on structure and function. Previous work has used CREST auto-antibodies with various microscopic techniques to map the locations of proteins within the centromere-kinetochore complex and to analyze the maturation of prekinetochores before mitosis. Here we have focused on the centromere-specific histone Centromere Protein (CENP)-A and its spatial relationship to other histones and histone modifications found in condensed chromatin. We demonstrate that the phosphorylation of histone H3 is essentially excluded from a specific region of centromeric chromatin, defined by the presence of CENP-A. Interspersion of CENP-B with phosphorylated H3 in the inner centromere indicates that the exclusion of H3 modification is not a general property of alpha-satellite DNA. We also demonstrate that these regions are functionally distinct by fragmenting mitotic chromatin into motile centromere-kinetochore fragments that contain CENP-A with little or no phosphorylated H3 and nonmotile fragments that contain exclusively phosphorylated H3. The sequence of CENP-A diverges from H3 in a number of key residues involved in chromosome condensation and in transcription, potentially allowing a more specialized chromatin structure within centromeric heterochromatin, on which kinetochore plates may nucleate and mature. This specialized centromere subdomain would be predicted to have a very tight and static nucleosome structure as a result of the absence of H3 phosphorylation and acetylation.
Van Hooser
A A
AA
Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
Mancini
M A
MA
Allis
C D
CD
Sullivan
K F
KF
Brinkley
B R
BR
D000595:Amino Acid Sequence; D000818:Animals; D001324:Autoantigens; D017675:CREST Syndrome / Q000276:immunology; D002503:Centromere / Q000737:chemistry / Q000502:physiology; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry / Q000502:physiology; D006657:Histones / Q000737:chemistry / Q000502:physiology; D008322:Mammals / Q000235:genetics; D008969:Molecular Sequence Data; D010766:Phosphorylation
D001324:Autoantigens; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone; D006657:Histones