title: CENPT bridges adjacent CENPA nucleosomes on young human α-satellite dimers.
abstract: Nucleosomes containing the CenH3 (CENPA or CENP-A) histone variant replace H3 nucleosomes at centromeres to provide a foundation for kinetochore assembly. CENPA nucleosomes are part of the constitutive centromere associated network (CCAN) that forms the inner kinetochore on which outer kinetochore proteins assemble. Two components of the CCAN, CENPC and the histone-fold protein CENPT, provide independent connections from the ∼171-bp centromeric α-satellite repeat units to the outer kinetochore. However, the spatial relationship between CENPA nucleosomes and these two branches remains unclear. To address this issue, we use a base-pair resolution genomic readout of protein-protein interactions, comparative chromatin immunoprecipitation (ChIP) with sequencing, together with sequential ChIP, to infer the in vivo molecular architecture of the human CCAN. In contrast to the currently accepted model in which CENPT associates with H3 nucleosomes, we find that CENPT is centered over the CENPB box between two well-positioned CENPA nucleosomes on the most abundant centromeric young α-satellite dimers and interacts with the CENPB/CENPC complex. Upon cross-linking, the entire CENPA/CENPB/CENPC/CENPT complex is nuclease-protected over an α-satellite dimer that comprises the fundamental unit of centromeric chromatin. We conclude that CENPA/CENPC and CENPT pathways for kinetochore assembly are physically integrated over young α-satellite dimers.
authors.affiliation: Howard Hughes Medical Institute, Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA.
authors.forename: Jitendra
authors.initials: J
authors.lastname: Thakur
authors.affiliation: Howard Hughes Medical Institute, Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Henikoff
mesh_terms: D002460:Cell Line; D002503:Centromere / Q000235:genetics; D000076247:Centromere Protein A / Q000235:genetics*; D051936:Centromere Protein B / Q000235:genetics*; D002843:Chromatin / Q000235:genetics; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics*; D004276:DNA, Satellite / Q000235:genetics; D006801:Humans; D018386:Kinetochores; D009707:Nucleosomes / Q000235:genetics; D054730:Protein Interaction Domains and Motifs
chemical_list: C000619700:CENPA protein, human; C497926:CENPB protein, human; C534001:CENPT protein, human; D000076247:Centromere Protein A; D051936:Centromere Protein B; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D004276:DNA, Satellite; D009707:Nucleosomes; C060905:centromere protein C