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

beta-Phosphoglucomutase (beta-PGM), a 28 kDa monomer, catalyzes the reversible conversion of beta-D-glucose-1-phosphate to beta-D-glucose-6-phosphate in maltose metabolism in a variety of organisms. Sequence analysis of beta-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. beta-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 P2(1)2(1)2(1), with unit-cell parameters a = 53.67, b = 92.78, c = 111.60 and a = 53.21, b = 57.01, c = 76.11 Angstrom. To solve the phase problem, selenomethionine (SeMet) containing alpha-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 Angstrom on crystals of the SeMet-substituted beta-PGM. The structure solution is currently being attempted by the multi-wavelength anomalous diffraction (MAD) phasing method.