The structure of (CENP-A-H4)(2) reveals physical features that mark centromeres.
Centromeres are specified epigenetically, and the histone H3 variant CENP-A is assembled into the chromatin of all active centromeres. Divergence from H3 raises the possibility that CENP-A generates unique chromatin features to mark physically centromere location. Here we report the crystal structure of a subnucleosomal heterotetramer, human (CENP-A-H4)(2), that reveals three distinguishing properties encoded by the residues that comprise the CENP-A targeting domain (CATD; ref. 2): (1) a CENP-A-CENP-A interface that is substantially rotated relative to the H3-H3 interface; (2) a protruding loop L1 of the opposite charge as that on H3; and (3) strong hydrophobic contacts that rigidify the CENP-A-H4 interface. Residues involved in the CENP-A-CENP-A rotation are required for efficient incorporation into centromeric chromatin, indicating specificity for an unconventional nucleosome shape. DNA topological analysis indicates that CENP-A-containing nucleosomes are octameric with conventional left-handed DNA wrapping, in contrast to other recent proposals. Our results indicate that CENP-A marks centromere location by restructuring the nucleosome from within its folded histone core.
Sekulic
Nikolina
N
Department of Biochemistry and Biophysics, University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania 19104-6059, USA.
Bassett
Emily A
EA
Rogers
Danielle J
DJ
Black
Ben E
BE
D000595:Amino Acid Sequence; D001324:Autoantigens / Q000737:chemistry* / Q000378:metabolism*; D001665:Binding Sites; D002503:Centromere / Q000737:chemistry* / Q000378:metabolism*; D000076247:Centromere Protein A; D042002:Chromatin Assembly and Disassembly; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D041961:Deuterium Exchange Measurement; D004843:Epistasis, Genetic; D006657:Histones / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009707:Nucleosomes / Q000737:chemistry / Q000378:metabolism; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D012399:Rotation; D053838:Scattering, Small Angle; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
D001324:Autoantigens; C000619700:CENPA protein, human; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone; D006657:Histones; D009707:Nucleosomes; D004247:DNA