EXPRESSION OF AN ACTIVE ADENYLATE-FORMING DOMAIN OF PEPTIDE SYNTHETASES CORRESPONDING TO ACYL-COA-SYNTHETASES

Peptide synthetases and acyl-CoA-synthetases form acyl adenylates which are transferred to CoA or enzyme-bound pantetheine. To verify the existence of an adenylate domain in peptide synthetases, a 60.8 kDa fragment of tyrocidine 1-synthetase was constructed by a 1629 bp deletion, expressed in Escherichia coli, and characterized. The truncated multienzyme activated phenylalanine and substrate analogues with comparable kinetics as the over-expressed synthetase, as judged by ATP[P-32]PPi exchange reaction. Thus the N-terminal domain resembling an acyl-CoA-synthetase is an autonomous structural element. This N-terminal domain is followed by a cofactor binding domain, resembling acyl carrier proteins involved in polyketide formation.