Overexpression, purification, crystallization and preliminary X-ray diffraction analysis of the receiver domain of PhoB

PhoB is the response regulator of the E. coli two-component signal transduc tion system for phosphate regulation. It is a transcription factor that act ivates more than 30 genes of the pho regulon. Crystals of the receiver doma in of PhoB were obtained by applying the hanging-drop vapour-diffusion meth od. X-ray diffraction data have been collected using synchrotron radiation to 1.88 Angstrom resolution. The crystals belong to the orthorhombic space group P2(1)2(1)2(1) with unit-cell constants a = 34.11, b = 60.42, c = 119. 97 Angstrom. The Matthews parameter suggests that PhoB crystallizes with tw o molecules per asymmetric unit, suggesting that activating dimerization oc curs in the crystal.