Crystallization and preliminary crystallographic analysis of the phosphotriesterase-like lactonase from Geobacillus kaustophilus.

GK1506 from the thermophilic bacterium Geobacillus kaustophilus is a member of the phosphotriesterase-like lactonases, which can catalyze the hydrolysis of a broad range of compounds with different chemical properties. It is of particular interest because of its high thermostability and its dual activity towards organophosphate compounds and some lactones. These properties make GK1506 an attractive target for future enzyme engineering and use in practical applications. In order to resolve the crystal structure of GK1506 and to gain a better understanding of its biological function, recombinant GK1506 was expressed, purified and crystallized using 0.1 M HEPES pH 7.6, 12%(w/v) PEG 8000, 8%(v/v) ethylene glycol at 291 K. A 2.6 Å resolution native data set was collected from a single flash-cooled crystal (100 K) using 10%(v/v) glycerol as a cryoprotectant. These crystals belonged to space group P2(1), with unit-cell parameters a=51.444, b=80.453, c=92.615 Å, β=99.29°. Two molecules were assumed to be present per asymmetric unit, which gives a Matthews coefficient of 2.7 Å3 Da(-1).