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CENP-C reshapes and stabilizes CENP-A nucleosomes at the centromere

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Science  08 May 2015:
Vol. 348, Issue 6235, pp. 699-703
DOI: 10.1126/science.1259308

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Building stable centromeres

Each of our chromosomes has a single centromere, seen as a constriction during cell division, which is required for accurate chromosome segregation to daughter cells. Falk et al. show that the special histone protein known as CENP-A, which forms part of the nucleosomes at centromeres, makes the chromatin at these constrictions very stable and long-lived. This stability is conferred by a protein-binding partner, CENP-C, recruited to the centromere by the CENP-A histone. Binding of CENP-C to CENP-A–containing nucleosomes alters the behavior of the macromolecular centromere complex to help it maintain its identity

Science, this issue p. 699

Abstract

Inheritance of each chromosome depends upon its centromere. A histone H3 variant, centromere protein A (CENP-A), is essential for epigenetically marking centromere location. We find that CENP-A is quantitatively retained at the centromere upon which it is initially assembled. CENP-C binds to CENP-A nucleosomes and is a prime candidate to stabilize centromeric chromatin. Using purified components, we find that CENP-C reshapes the octameric histone core of CENP-A nucleosomes, rigidifies both surface and internal nucleosome structure, and modulates terminal DNA to match the loose wrap that is found on native CENP-A nucleosomes at functional human centromeres. Thus, CENP-C affects nucleosome shape and dynamics in a manner analogous to allosteric regulation of enzymes. CENP-C depletion leads to rapid removal of CENP-A from centromeres, indicating their collaboration in maintaining centromere identity.

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