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The β-lactamase inhibitor clavulanic acid is formed by condensation of a pyruvate-derived C3 unit with a molecule of arginine. A gene (pyc , for pyruvate converting) located upstream of thebls gene in the clavulanic acid gene cluster ofStreptomyces clavuligerus encodes a 582-amino-acid protein with domains recognizing pyruvate and thiamine pyrophosphate that shows 29.9% identity to acetohydroxyacid synthases. Amplification of thepyc gene resulted in an earlier onset and higher production of clavulanic acid. Replacement of thepyc gene with theaph gene did not cause isoleucine-valine auxotrophy in the mutant. Thepyc replacement mutant did not produce clavulanic acid in starch-asparagine (SA) or in Trypticase soy broth (TSB) complex medium, suggesting that thepyc gene product is involved in the conversion of pyruvate into the C3 unit of clavulanic acid. However, the β-lactamase inhibitor was still formed at the same level as in the wild-type strain in defined medium containingd -glycerol, glutamic acid, and proline (GSPG medium) as confirmed by high-pressure liquid chromatography and paper chromatography. The production of clavulanic acid by the replacement mutant was dependent on addition of glycerol to the medium, and glycerol-free GSPG medium did not support clavulanic acid biosynthesis, suggesting that an alternative gene product catalyzes the incorporation of glycerol into clavulanic acid in the absence of the Pyc protein. Thepyc replacement mutant overproduces cephamycin.

journal of bacteriology

Deletion of the <i>pyc</i> Gene Blocks Clavulanic Acid Biosynthesis Except in Glycerol-Containing Medium: Evidence for Two Different Genes in Formation of the C3 Unit

Deletion of the pyc Gene Blocks Clavulanic Acid Biosynthesis Except in Glycerol-Containing Medium: Evidence for Two Different Genes in Formation of the C3 Unit