DNA replication-mediated error correction of ectopic CENP-A deposition maintains centromere identity

Chromatin assembled with histone H3 variant CENP-A is the heritable epigenetic determinant of human centromere identity. Using genome-wide mapping and reference models for 23 human centromeres, CENP-A is shown in early G1 to be assembled into nucleosomes within megabase, repetitive a-satellite DNAs at each centromere and onto 11,390 sites on the chromosome arms. Centromere-bound CENP-A is found to be quantitatively maintained during DNA replication by coordinated action of the MCM2 helicase, CAF1, HJURP, and the CCAN network of constitutive centromere components. CCAN serves to tether CENP-A removed by MCM2, thereby enabling local reassembly onto both daughter centromeres with identical DNA sequence preferences and nucleosome phasing as the loading in G1 and independent of CENP-B. Conversely, without CCAN-mediated tethering, DNA replication removes CENP-A from sites on the chromosome arms. Our data identify an MCM2/CAF1/HJURP- and CCAN-dependent error correction mechanism that acts in S-phase to maintain CENP-A-dependent centromere identity. Centromere protein A ChIP-seq during different stages of the cell cycle and with reference to replication data