Molecular cloning of enantioselective ester hydrolase from Bacillus pumilus DBRL-191

A gene from Bacillus pumilus expressed under its native promoter was cloned in Escherichia coli. Recombinant B. pumilus esterase (BPE) affects the kinetic resolution of racemic mixtures such as unsubstituted and substituted 1-(phenyl)ethanols (E ∼ 33-103), ethyl 3-hydroxy-3-phenylpropanoate (E ∼ 45-71), trans-4-fluorophenyl-3-hydroxymethyl-N-methylpiperidine (E ∼ 10-13) and ethyl 2-hydroxy-4-phenylbutyrate (E ∼ 7). The enzyme is composed of a 34-amino acid signal peptide and a 181-amino acid mature protein corresponding to a molecular weight of ∼19.2 kD and pI ∼ 9.4. 3-D the structural model of the enzyme built by homology modelling using the atomic coordinates from the crystal structure of B. subtilis lipase (LipA) showed a compact minimal α/β hydrolase fold.