The nucleosomal core histone octamer at 3.1 A resolution: a tripartite protein assembly and a left-handed superhelix.
The structure of the octameric histone core of the nucleosome has been determined by x-ray crystallography to a resolution of 3.1 A. The histone octamer is a tripartite assembly in which a centrally located (H3-H4)2 tetramer is flanked by two H2A-H2B dimers. It has a complex outer surface; depending on the perspective, the structure appears as a wedge or as a flat disk. The disk represents the planar projection of a left-handed proteinaceous superhelix with approximately 28 A pitch. The diameter of the particle is 65 A and the length is 60 A at its maximum and approximately 10 A at its minimum extension; these dimensions are in agreement with those reported earlier by Klug et al. [Klug, A., Rhodes, D., Smith, J., Finch, J. T. & Thomas, J. O. (1980) Nature (London) 287, 509-516]. The folded histone chains are elongated rather than globular and are assembled in a characteristic "handshake" motif. The individual polypeptides share a common central structural element of the helix-loop-helix type, which we name the histone fold.
Arents
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Department of Biology, Johns Hopkins University, Baltimore, MD 21218.
Burlingame
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Wang
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Love
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Moudrianakis
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D000818:Animals; D002645:Chickens; D003196:Computer Graphics; D003198:Computer Simulation; D004912:Erythrocytes / Q000648:ultrastructure; D006657:Histones / Q000737:chemistry*; D046911:Macromolecular Substances; D008958:Models, Molecular; D009707:Nucleosomes / Q000648:ultrastructure*; D010781:Photography; D011487:Protein Conformation; D014961:X-Ray Diffraction / Q000379:methods
D006657:Histones; D046911:Macromolecular Substances; D009707:Nucleosomes