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Co-localization of CENP-C and CENP-H to discontinuous domains of CENP-A chromatin at human neocentromeres

DOI: 10.1186/gb-2007-8-7-r148

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Abstract:

We have examined the distribution of CENP-A, as well as two additional centromeric chromatin-associated proteins (CENP-C and CENP-H), across neocentromeric DNA using chromatin immunoprecipitation (ChIP) on CHIP assays on custom genomic microarrays at three different resolutions. Analysis of two neocentromeres using a contiguous bacterial artificial chromosome (BAC) microarray spanning bands 13q31.3 to 13q33.1 shows that both CENP-C and CENP-H co-localize to the CENP-A chromatin domain. Using a higher resolution polymerase chain reaction (PCR)-amplicon microarray spanning the neocentromere, we find that the CENP-A chromatin is discontinuous, consisting of a major domain of about 87.8 kilobases (kb) and a minor domain of about 13.2 kb, separated by an approximately 158 kb region devoid of CENPs. Both CENP-A domains exhibit co-localization of CENP-C and CENP-H, defining a distinct inner kinetochore chromatin structure that is consistent with higher order chromatin looping models at centromeres. The PCR microarray data suggested varying density of CENP-A nucleosomes across the major domain, which was confirmed using a higher resolution oligo-based microarray.Centromeric chromatin consists of several CENP-A subdomains with highly discontinuous CENP-A chromatin at both the level of individual nucleosomes and at higher order chromatin levels, raising questions regarding the overall structure of centromeric chromatin.The centromere, which is the chromosome component that is responsible for the proper segregation of sister chromatids to daughter cells during cell division, is a specialized chromatin structure [1,2]. Centromeric chromatin has a distinctive nucleosome structure that contains the histone H3 variant centromere protein (CENP)-A [3-8]. CENP-A containing chromatin associates with a large number of proteins, which are assembled in a hierarchical manner [9-12]. Essential among the proximal proteins are several associated with the centromere throughout the cell cycle,

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