Crystallization and preliminary crystallographic studies of UbiG, an O-methyltransferase from Escherichia coli

UbiG, an O-methyltransferase from the ubiquinone-biosynthesis pathway in Escherichia coli, catalyzes two O-methyl transfer steps. The primary structures of the O-methyltransferase enzyme family used in ubiquinone synthesis are conserved in both prokaryotes and eukaryotes, but their tertiary structures and catalytic mechanisms are not yet known. Here, UbiG with an N-terminal hexahistidine tag was expressed and crystallized. Crystals grown by the hanging-drop vapour-diffusion method diffracted to 2.00 angstrom resolution and belonged to space group C121, with unit-cell parameters a = 119.8, b = 58.6, c = 40.2 angstrom, beta = 105.3 degrees. Both Matthews coefficient analysis and the self-rotation function suggested the presence of one molecule per asymmetric unit in the crystal, with a solvent content of 50.52% (V-M = 2.48 angstrom(3) Da(-1)).