CENP-C unwraps the human CENP-A nucleosome through the H2A C-terminal tail.Ali-Ahmad, A., Bilokapic, S., Schafer, I.B., Halic, M., Sekulic, N.
(2019) EMBO Rep 20: e48913-e48913
- PubMed: 31475439
- DOI: https://doi.org/10.15252/embr.201948913
- Primary Citation of Related Structures:
6SE0, 6SE6, 6SEE, 6SEF, 6SEG
- PubMed Abstract:
Centromeres are defined epigenetically by nucleosomes containing the histone H3 variant CENP-A, upon which the constitutive centromere-associated network of proteins (CCAN) is built. CENP-C is considered to be a central organizer of the CCAN. We provide new molecular insights into the structure of human CENP-A nucleosomes, in isolation and in complex with the CENP-C central region (CENP-C CR ), the main CENP-A binding module of human CENP-C. We establish that the short αN helix of CENP-A promotes DNA flexibility at the nucleosome ends, independently of the sequence it wraps. Furthermore, we show that, in vitro, two regions of human CENP-C (CENP-C CR and CENP-C motif ) both bind exclusively to the CENP-A nucleosome. We find CENP-C CR to bind with high affinity due to an extended hydrophobic area made up of CENP-A V 532 and CENP-A V 533 . Importantly, we identify two key conformational changes within the CENP-A nucleosome upon CENP-C binding. First, the loose DNA wrapping of CENP-A nucleosomes is further exacerbated, through destabilization of the H2A C-terminal tail. Second, CENP-C CR rigidifies the N-terminal tail of H4 in the conformation favoring H4 K20 monomethylation, essential for a functional centromere.
Centre for Molecular Medicine Norway (NCMM), Nordic EMBL Partnership, University of Oslo, Oslo, Norway.