Crystallization and preliminary analysis of xenobiotic reductase A and ligand complexes from Pseudomonas putida II-B.

Diffraction-quality crystals have been obtained of the xenobiotic reductase A (XenA) from Pseudomonas II-B, which was originally cultured from the contaminated soil of a World War II era munitions-manufacturing plant. Several complete X-ray diffraction data sets have been collected and analyzed. The native XenA data set includes reflections between 35 and 1.65 A. Four-wavelength MAD data sets from selenomethionine-enriched XenA and from three different ligand complexes are also reported. The XenA crystals belong to space group P2(1)2(1)2, with unit-cell parameters a = 84, b = 158, c = 57 A. Experimental phasing from analysis of the MAD data from selenomethionine-enriched XenA reveals the presence of two molecules in the asymmetric unit. They are related by a non-crystallographic 2(1) screw axis nearly parallel to the c axis, but offset by a quarter unit-cell translation. Thus, the local symmetry produces approximate systematic absences along the (00l) principal axis and complicates the space-group determination.