Catabolite Repression in the d -Serine Deaminase System of Escherichia coli K-12

Abstract

The induced synthesis of d -serine deaminase in Escherichia coli is subject to three catabolic effects: inhibition on inducer uptake, transient repression, and catabolite repression. Inhibition on d -serine uptake is not significant at the d -serine concentration normally used for induction. Transient repression and catabolite repression of d -serine deaminase synthesis are abolished by mutations in dsdCy , which appears to be an operator locus. The decline in the rate of constitutive synthesis observed in dsdCx mutants growing with glycerol as carbon source at temperatures above 37 C is due to catabolite repression. The low level of constitutivity at 37 C and the partial cis dominance of dsdCx mutants are not artifacts of catabolite repression. It is suggested that a product of one of the genes of the dsd operon may regulate the expression of the operon.