Crystallization and preliminary X-ray analysis of 4-­pyridoxolactonase from Mesorhizobium loti

4-Pyridoxolactonase from Mesorhizobium loti MAFF303099 has been overexpressed in Escherichia coli. The recombinant enzyme was purified and was crystallized by the sitting-drop vapour-diffusion method using PEG 4000 and ammonium sulfate as precipitants. Crystals of the free enzyme (form I) and of the 5-pyridoxolactone-bound enzyme (form II) grew under these conditions. Crystals of form I diffracted to 2.0 Å resolution and belonged to the monoclinic space group C2, with unit-cell parameters a = 77.93, b = 38.88, c = 81.60 Å, β = 117.33°. Crystals of form II diffracted to 1.9 Å resolution and belonged to the monoclinic space group C2, with unit-cell parameters a = 86.24, b = 39.35, c = 82.68 Å, β = 118.02°. The calculated V_M values suggested that the asymmetric unit contains one molecule in both crystal forms.