1hq3

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spinqualitylabelsall models 1hq3, resolution 2.15Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

CRYSTAL STRUCTURE OF THE HISTONE-CORE-OCTAMER IN KCL/PHOSPHATE

Overview

The structure of the native chicken histone octamer, crystallized in 2 M, KCl, 1.35 M potassium phosphate pH 6.9, has been refined at 2.15 A, resolution to a final R factor of 21.4% and an R(free) of 25.2%. Unique, crystal-packing interactions between histone-core octamers are strong and, one of them (area 4000 A(2)) involves two chloride ions and direct, interactions between six acidic amino-acid residues on one octamer and the, equivalent number of basic residues on the next. These interactions are on, the structured part of the octamer (not involving tails). Five phosphate, ions, 23 chloride ions and 437 water molecules have been identified in the, structure. The phosphate and some chloride ions bind to basic amino-acid, residues that interact with DNA in the nucleosome. The binding of most of, the anions and the packing interactions are unique to these crystals. In, other respects, and including the positions of four chloride ions, the, octamer structure is very close to that of octamers in nucleosome-core, particle crystals, particularly with respect to 'docking' sequences of the, histone H2As and H4s. These sequences together with the H2B-H4 four-helix, bundles stabilize the histone structure in the nucleosome and prevent the, dissociation of the (H2A-H2B) dimers from the (H3-H4)(2) tetramer., Possible reasons why this happens at high salt in the absence of DNA are, given.

About this Structure

1HQ3 is a Protein complex structure of sequences from Gallus gallus with PO4 and CL as ligands. Full crystallographic information is available from OCA.

Reference

Structure of the histone-core octamer in KCl/phosphate crystals at 2.15 A resolution., Chantalat L, Nicholson JM, Lambert SJ, Reid AJ, Donovan MJ, Reynolds CD, Wood CM, Baldwin JP, Acta Crystallogr D Biol Crystallogr. 2003 Aug;59(Pt 8):1395-407. Epub 2003, Jul 23. PMID:12876341

Page seeded by OCA on Tue Nov 20 16:44:07 2007