Internal symmetry of the molecular chaperone cpn60 (GroEL) determined by X-ray crystallography.
The Escherichia coli molecular chaperone cpn60 oligomer, [cpn60](14), also called GroEL, has been crystallized and examined by X-ray crystallography and self-rotation function calculations. The crystals show unit-cell dimensions a = 143.3, b = 154.6 and c = 265 A, with alpha = 82, beta = 95 and gamma = 107 degrees. The space group is P1 and crystals diffract to 7 A. X-ray analysis shows that the oligomer has one sevenfold symmetry axis and seven twofold axes that are all perpendicular to the sevenfold. The symmetry suggests that [cpn60](24) consists of two heptamers, [cpn60](7), stacked on top of each other. The orientations of the symmetry axes of the two independent [cpn60](14) oligomers in the triclinic unit cell have been determined relative to the crystallographic axes. The two oligomers in the unit cell are arranged side-by- side, but the second oligomer is rotated 26 degrees around the sevenfold axis relative to the first oligomer.
Spangfort
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MD
Department of Molecular Biophyiscs, Chemical Center, University of Lund, Sweden.
Surin
B P
BP
Dixon
N E
NE
Svensson
L A
LA