Crystallization and preliminary X-ray diffraction studies of β-phosphoglucomutase from Lactococcus lactus

β-Phosphoglucomutase (β-PGM), a 28 kDa monomer, catalyzes the reversible conversion of β-D-glucose-1-phosphate to β-D-glucose-6-­phosphate in maltose metabolism in a variety of organisms. Sequence analysis of β-PGM indicates that it is a member of the haloacid dehalogenase (HAD) enzyme superfamily, which evolved to cleave C—Cl, C—P and C—OP bonds in a variety of substrates. β-­PGM has been crystallized using the hanging-drop method. Diffraction-quality crystals of the native protein have been obtained from two conditions, both belonging to space group P2₁2₁2₁, with unit-cell parameters a = 53.67, b = 92.78, c = 111.60 and a = 53.21, b = 57.01, c = 76.11 Å. To solve the phase problem, selenomethionine (SeMet) containing β-PGM crystals have been grown. The SeMet-containing crystals diffract to high resolution only when grown by microseeding with native crystals. A three-wavelength data set has been collected to 2.3 Å on crystals of the SeMet-substituted β-PGM. The structure solution is currently being attempted by the multiwavelength anomalous diffraction (MAD) phasing method.