High-resolution structure of the native histone octamer

• Published in: Acta crystallographica. Section F, Structural biology and crystallization communications Structural biology and crystallization communications, 2005-06, Vol.61 (6), p.541-545
• Main Authors: Wood, Christopher M., Nicholson, James M., Lambert, Stanley J., Chantalat, Laurent, Reynolds, Colin D., Baldwin, John P.
• Format: Article
• Language: English
• Subjects: Animals; Chickens; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Crystallography, X-Ray; CRYSTALS; Dimerization; DIMERS; Erythrocytes - chemistry; histone octamer; Histones - chemistry; INSTABILITY; INTERACTIONS; MOLECULAR CLUSTERS; Molecular Structure; MOLECULES; Nucleosomes - chemistry; POTASSIUM PHOSPHATES; Protein Binding; Protein Conformation; Protein Structure Communications; RESOLUTION; SHEETS; SPACE GROUPS; WATER; Water - chemistry
• ISSN: 1744-3091; 1744-3091
• DOI: 10.1107/S1744309105013813

Crystals of native histone octamers (H2A–H2B)–(H4–H3)–(H3′–H4′)–(H2B′–­H2A′) from chick erythrocytes in 2 M KCl, 1.35 M potassium phosphate pH 6.9 diffract X‐rays to 1.90 Å resolution, yielding a structure with an Rwork value of 18.7% and an Rfree of 22.2%. The crystal space group is P65, the asymmetric unit of which contains one complete octamer. This high‐resolution model of the histone‐core octamer allows further insight into intermolecular interactions, including water molecules, that dock the histone dimers to the tetramer in the nucleosome‐core particle and have relevance to nucleosome remodelling. The three key areas analysed are the H2A′–H3–H4 molecular cluster (also H2A–H3′–H4′), the H4–H2B′ interaction (also H4′–H2B) and the H2A′–H4 β‐sheet interaction (also H2A–H4′). The latter of these three regions is important to nucleosome remodelling by RNA polymerase II, as it is shown to be a likely core‐histone binding site, and its disruption creates an instability in the nucleosome‐core particle. A majority of the water molecules in the high‐resolution octamer have positions that correlate to similar positions in the high‐­resolution nucleosome‐core particle structure, suggesting that the high‐resolution octamer model can be used for comparative studies with the high‐resolution nucleosome‐core particle.