EXPRESSION IN ESCHERICHIA-COLI OF A CLAVAMINIC ACID SYNTHASE ISOZYME - A TRIFUNCTIONAL OXYGENASE INVOLVED IN CLAVULANIC ACID BIOSYNTHESIS

Purification and sequencing of clavaminic acid synthase (CAS) activiti es from S. clavuligerus SC2 provided evidence for the existence of two CAS isozymes. One of these isozymes was cloned and expressed in E. co li. The recombinant CAS isozyme was shown to catalyse the hydroxylatio n of (2S)-5-guanidino-2-(2'-oxoazetidin-1'-yl)pentanoic acid, in addit ion to the production of clavaminic acid from dihydroclavaminic acid v ia proclavaminic acid consistent with the trifunctional role proposed for clavaminic acid synthase in the biosynthesis of clavulanic acid. A preliminary purification and characterisation of the recombinant isoz yme is reported.