Purification, crystallization and preliminary X-ray studies of ClpX from Helicobacter pylori

ClpX, a member of the HSP (heat-shock protein) 100 family, functions as a molecular chaperone and is a regulatory subunit of the ClpXP protease. To understand the chaperone and regulatory mechanisms of ClpX, Helicobacter pylori ClpX has been overexpressed in Escherichia coli and crystallized at 295 K using (NH4)(2)HPO4 as precipitant. X-ray diffraction data have been collected to 2.6 Angstrom resolution using a synchrotron-radiation source. The crystals belong to the hexagonal space group P6(5) or P6(1), with unit-cell parameters a = b = 78.52 (04), c = 131.51 (09) Angstrom, alpha = beta = 90, gamma = 120degrees. The crystallographic asymmetric unit contains one molecule of ClpX, with a corresponding V-M of 2.78 Angstrom(3) Da(-1) and a solvent content of 55.8%.