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 over-expressed in Escherichia coli and crystallized at 295 K using (NH₄)₂HPO₄ as precipitant. X-ray diffraction data have been collected to 2.6 Å resolution using a synchrotron-radiation source. The crystals belong to the hexagonal space group P6₅ or P6₁, with unit-cell parameters a = b = 78.52 (04), c = 131.51 (09) A, α = β = 90, γ= 120°. The crystallographic asymmetric unit contains one molecule of ClpX, with a corresponding V_M of 2.78 ų Da^-1 and a solvent content of 55.8%.