Crystallization and preliminary X-ray crystallographic analysis of Thermotoga maritima CheA P3-P4-P5 domains in complex with CheW.

The CheA-CheW complex plays a key role in bacterial chemotaxis signal transduction by initiating phosphotransfer to response regulators via coupling to the chemoreceptors. CheA (P3-P4-P5 domains) and CheW from Thermotoga maritima were overexpressed in Escherichia coli and crystallized as a complex at 298 K using ammonium dihydrogen phosphate as a precipitant. X-ray diffraction data were collected to ~8 Å resolution at 100 K using synchrotron radiation. The crystal belonged to space group I222 or I2(1)2(1)2(1), with unit-cell parameters a = 184.2, b = 286.4, c = 327.7 Å. The asymmetric unit may contain six to ten CheA-CheW molecules.