MOLECULAR-CLONING AND CHARACTERIZATION OF FENGYCIN SYNTHETASE GENE FENB FROM BACILLUS-SUBTILIS

A fengycin synthetase gene, fenB, has been cloned and sequenced. The p rotein (FenB) encoded by this gene has a predicted molecular mass of 1 43.6 kDa. This protein was overexpressed in Escherichia coli and was p urified to near homogeneity by affinity chromatography. Experimental r esults indicated that the recombinant FenB has a substrate specificity toward isoleucine with an optimum temperature of 25 degrees C, an opt imum pH of 4.5, a K-m value of 922 mu M, and a turnover number of 236 s(-1). FenB also consists of a thioesterase domain, suggesting that th is protein mag be involved in tile activation of the last amino acid o f fengycin.