Expression in Escherichia coli of a Clavaminic Acid Synthase Isozyme: A Trifunctional Oxygenase Involved in Clavulanic Acid Biosynthesis.

Abstract Purification and sequencing of clavaminic acid synthase (CAS) activities from S. clavuligerus SC2 provided evidence for the existence of two CAS isozymes. One of these isozymes was cloned and expressed in E. coli. The recombinant CAS isozyme was shown to catalyse the hydroxylation of (2S)-5-guanidino-2-(2′-oxoazetidin-1′-yl)pentanoic acid, in addition to the production of clavaminic acid from dihydroclavaminic acid via proclavaminic acid, consistent with the trifunctional role proposed for clavaminic acid synthase in the biosynthesis of clavulanic acid. A preliminary purification and characterisation of recombinant isozyme is reported.