A thermostable and alkaline GDSL-motif esterase from Bacillus sp. K91: crystallization and X-ray crystallographic analysis

The esterase Est8 from the thermophilic bacterium Bacillus sp. K91 belongs to the GDSL family and is active on a variety of acetylated compounds, including 7-aminocephalosporanic acid. In contrast to other esterases of the GDSL family, the catalytic residues Asp182 and His185 were more pivotal for the catalytic activity of Est8 than the Ser11 residue. To better understand the biochemical and enzymatic properties of Est8, recombinant Est8 protein was purified and crystallized. Crystals of Est8 were obtained by the hanging-drop vapour-diffusion method using 2.0 M ammonium sulfate, 5%(v/v) 2-propanol as the crystallization solution. X-ray diffraction data were collected to a resolution of 2.30 Å with an R (merge) of 16.4% from a crystal belonging to space group P4(1)2(1)2 or P4(3)2(1)2, with unit-cell parameters a = b = 68.50, c = 79.57 Å.