PRECURSOR FLUX CONTROL THROUGH TARGETED CHROMOSOMAL INSERTION OF THE LYSINE EPSILON-AMINOTRANSFERASE (LAT) GENE IN CEPHAMYCIN C BIOSYNTHESIS

Targeted gene insertion methodology was used to study the effect of pe rturbing alpha-aminoadipic acid precursor flux on the overall producti on rate of beta-lactam biosynthesis in Streptomyces clavuligerus. A hi gh-copy-number plasmid containing the lysine epsilon-aminotransferase gene (lat) was constructed and used to transform S. clavuligerus. The resulting recombinant strain (LHM100) contained an additional complete copy of lat located adjacent to the corresponding wild-type gene in t he chromosome. Biological activity and production levels of beta-lacta m antibiotics were two to five times greater than in wild-type S. clav uligerus. Although levels of lysine epsilon-aminotransferase were elev ated fourfold in LHM100, the level of ACV synthetase, whose gene is lo cated just downstream of lat, remained unchanged. These data strongly support the notion that direct perturbation of alpha-aminoadipic acid precursor flux resulted in increased antibiotic production. This strat egy represents a successful application of metabolic engineering based on theoretical predictions of precursor flux in a secondary metabolic pathway.