Catabolite repression and nitrogen control of allantoin-degrading enzymes in Pseudomonas aeruginosa.

The formation of the allantoin-degrading enzymes allantoinase, allantoicase and ureidoglycolase in Pseudomonas aeruginosa was found to be regulated by induction, catabolite repression and nitrogen control. Induction was observed when urate, allantoin or allantoate were included in the growth medium, but not with ureidoglycolate. Tricarboxylic acid cycle intermediates exerted catabolite repression of the synthesis of the three enzymes, while pyruvate and glucose caused less repression. The operation of a nitrogen control mechanism in the regulation of the allantoin-degrading enzymes could be demonstrated with glutamine synthetase-negative mutants, which showed elevated synthesis and escape from catabolite repression when growth was limited for glutamine.