Dual recognition of CENP-A nucleosomes is required for centromere assembly.
Centromeres contain specialized nucleosomes in which histone H3 is replaced by the histone variant centromere protein A (CENP-A). CENP-A nucleosomes are thought to act as an epigenetic mark that specifies centromere identity. We previously identified CENP-N as a CENP-A nucleosome-specific binding protein. Here, we show that CENP-C also binds directly and specifically to CENP-A nucleosomes. Nucleosome binding by CENP-C required the extreme C terminus of CENP-A and did not compete with CENP-N binding, which suggests that CENP-C and CENP-N recognize distinct structural elements of CENP-A nucleosomes. A mutation that disrupted CENP-C binding to CENP-A nucleosomes in vitro caused defects in CENP-C targeting to centromeres. Moreover, depletion of CENP-C with siRNA resulted in the mislocalization of all other nonhistone CENPs examined, including CENP-K, CENP-H, CENP-I, and CENP-T, and led to a partial reduction in centromeric CENP-A. We propose that CENP-C binds directly to CENP-A chromatin and, together with CENP-N, provides the foundation upon which other centromere and kinetochore proteins are assembled.
Carroll
Christopher W
CW
Department of Biochemistry, Stanford University School of Medicine, Palo Alto, CA 94503, USA.
Milks
Kirstin J
KJ
Straight
Aaron F
AF
D001324:Autoantigens / Q000378:metabolism*; D002503:Centromere / Q000378:metabolism*; D000076247:Centromere Protein A; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone / Q000172:deficiency / Q000378:metabolism*; D006801:Humans; D009154:Mutation; D009707:Nucleosomes / Q000378:metabolism*; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000494:pharmacology
D001324:Autoantigens; C000619700:CENPA protein, human; D000076247:Centromere Protein A; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D009707:Nucleosomes; D034741:RNA, Small Interfering; C060905:centromere protein C