Crystallization and preliminary X-ray crystallographic studies of AfeH from <i>Acimetobacter</i> sp. DL-2

Fenoxaprop-P-ethyl (FE) is widely applied as a post-emergence aryloxyphenoxy propionate (AOPP) herbicide in agriculture. A novel FE hydrolase esterase from Acinetobacter sp. DL-2 (AfeH) was identified which belongs to the family IV carboxylesterases and shows less than 30% identity to other reported homologues with known structure. In order to understand the catalytic mechanism, recombinant AfeH was prepared in Escherichia coli and crystallized using the sitting-drop vapor-diffusion method. X-ray diffraction data were collected to 1.9 Å resolution. The crystal belonged to space group P12₁1, with unit-cell parameters a = 84.27, b = 46.74, c = 258.68 Å. The Matthews coefficient (V_M) was calculated to be 2.43 ų Da^-1, which corresponds to a solvent content of 49.4%, suggesting the presence of three monomers in the crystallographic asymmetric unit. The crystal was assessed to be suitable for further structural determination, which is currently in progress.