A membrane-bound esterase PA2949 from Pseudomonas aeruginosa is expressed and purified from Escherichia coli

Pseudomonasaeruginosa strain 1001 produces an esterase (EstA) that can hydrolyse the racemic methyl ester of -acetylthioisobutyrate to produce the (D)-enantiomer, which serves as a precursor of captopril, a drug used for treatment of hypertension. We show here that PA2949 from P.aeruginosa PA01, a homologue of EstA, can efficiently be expressed in an enzymatically active form in E.coli. The enzyme is membrane-associated as demonstrated by cell fractionation studies. PA2949 was purified to homogeneity after solubilisation with the nonionic detergent, Triton X-100, and was shown to possess a conserved esterase catalytic triad consisting of Ser137-His258-Asp286. Our results should allow the development of an expression and purification strategy to produce this biotechnologically relevant esterase in a pure form with a high yield.