Transcriptional Studies on a Streptomyces clavuligerus oppA2 Deletion Mutant: N -Acetylglycyl-Clavaminic Acid Is an Intermediate of Clavulanic Acid Biosynthesis

Theoppa2 gene encodes an oligopeptide permease essential for the production of clavulanic acid. A transcriptomic analysis ofS. clavuligerus ΔoppA2 ::aac in comparison to the parental strainS. clavuligerus ATCC 27064 is reported. The lack of OppA2 results in different expression of 233 genes, including genes for proteases and genes for transport systems. The expression of the clavulanic acid genes in theoppA2 mutant is not significantly affected, but the genes for holomycin biosynthesis are strongly upregulated, in agreement with the higher holomycin production by this strain. TheoppA2 -mutant is known to releaseN -acetylglycyl-clavaminic acid to the broth. Cosynthesis assays using non-clavulanic acid-producing mutants showed that the addition of pureN -acetylglycyl-clavaminic acid to mutants in which clavulanic acid formation was blocked resulted in the recovery of clavulanic acid production, but only in mutants blocked in the early steps of the pathway. This suggests thatN -acetylglycyl-clavaminic acid is a previously unknown late intermediate of the clavulanic acid pathway.