Cloning and expression in Escherichia coli of apolyurethane-degrading enzyme from Pseudomonasfluorescens

A polyester polyurethane (PU)-degrading enzyme, PU esterase, derived from Pseudomonas fluorescens, a bacterium that utilizes polyester PU as the sole carbon source,was purified to homogeneity as indicated by sodium dodecyl sulfate-polyacrylamide gelelectrophoresis. This enzyme was a soluble, extracellular protein with a molecular mass of 48 kDa and was inhibited by phenylmethylsulfonylfluoride (PMSF). A genomic library of Ps.fluorescens was constructed using the Escherichia coli bacteriophage l vector lZAPII. A recombinant phage exhibiting activity against Impranil DLN was isolated. The geneencoding the polyurethanase (PUase) protein was subcloned into a plasmid expression vectorpT7-6 and expressed in E. coli. Upon expression, the PUase was secreted by the host,displayed esterase activity which was inhibited by PMSF, and in vivo ³⁵S-methionine labeling of the gene product encoded by the open reading frame of the clone insertrevealed a single polypeptide with a molecular mass of 48 kDa.