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Dornblut, C,Quinn, N,Monajambashi, S,Prendergast, L,van Vuuren, C,Munch, S,Deng, W,Leonhardt, H,Cardoso, MC,Hoischen, C,Diekmann, S,Sullivan, KF
2014
February
Open Biology
A CENP-S/X complex assembles at the centromere in S and G2 phases of the human cell cycle
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centromere mitosis constitutive centromere-associated network kinetochore LIVING HUMAN-CELLS A CHROMATIN MESSENGER-RNA HISTONE H3 PROTEIN DNA CORE MAINTENANCE DYNAMICS SCM3
4
The functional identity of centromeres arises from a set of specific nucleoprotein particle subunits of the centromeric chromatin fibre. These include CENP-A and histone H3 nucleosomes and a novel nucleosome-like complex of CENPs -T, -W, -S and -X. Fluorescence cross-correlation spectroscopy and Forster resonance energy transfer (FRET) revealed that human CENP-S and -X exist principally in complex in soluble form and retain proximity when assembled at centromeres. Conditional labelling experiments show that they both assemble de novo during S phase and G2, increasing approximately three-to fourfold in abundance at centromeres. Fluorescence recovery after photobleaching (FRAP) measurements documented steady-state exchange between soluble and assembled pools, with CENP-X exchanging approximately 10 times faster than CENP-S (t(1/2) similar to 10 min versus 120 min). CENP-S binding to sites of DNA damage was quite distinct, with a FRAP half-time of approximately 160 s. Fluorescent two-hybrid analysis identified CENP-T as a uniquely strong CENP-S binding protein and this association was confirmed by FRET, revealing a centromere-bound complex containing CENP-S, CENP-X and CENP-T in proximity to histone H3 but not CENP-A. We propose that deposition of the CENP-T/W/S/X particle reveals a kinetochore-specific chromatin assembly pathway that functions to switch centromeric chromatin to a mitosis-competent state after DNA replication. Centromeres shuttle between CENP-A-rich, replication-competent and H3-CENP-T/W/S/X-rich mitosis-competent compositions in the cell cycle.
ARTN 130229
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