Crystallization And X-Ray Diffraction Analysis Of The Ch Domain Of The Cotton Kinesin Ghkch2

GhKCH2 belongs to a group of plant-specific kinesins (KCHs) containing an actin-binding calponin homology (CH) domain in the N-terminus. Previous studies revealed that the GhKCH2 CH domain (GhKCH2-CH) had a higher affinity for F-actin (K-d = 0.42 +/- 0.02 mu M) than most other CH-domain-containing proteins. To understand the underlying mechanism, prokaryotically expressed GhKCH2-CH (amino acids 30-166) was purified and crystallized. Crystals were grown by the sitting-drop vapour-diffusion method using 0.1 M Tris-HCl pH 7.0, 20%(w/v) PEG 8000 as a precipitant. The crystals diffracted to a resolution of 2.5 angstrom and belonged to space group P2(1), with unit-cell parameters a = 41.57, b = 81.92, c = 83.00 angstrom, alpha = 90.00, beta = 97.31, gamma = 90.00 degrees. Four molecules were found in the asymmetric unit with a Matthews coefficient of 2.22 angstrom(3) Da(-1), corresponding to a solvent content of 44.8%.