title: Isolation and characterization of catabolite-resistant mutants in the D-serine deaminase system of Escherichia coli K-12.
abstract: Two classes of D-serine deaminase (Dsdase)-specific secondary mutants of Escherichia coli K-12 were isolated from a Dsdase low constitutive nonhyperinducible mutant as types which could grow in the presence of both D-serine and glucose. These strains contain cis dominant, nonsuppressible mutations in the dsdO (operator-initiator) region. In the first class of mutants (e.g., FB4010), Dsdase synthesis is completely insensitive to catabolite repression, and synthesis occurs at a high constitutive rate in the absence of cyclic adenosine 5'-monophosphate. In the second class (e.g., FB4005), Dsdase synthesis is partially insensitive to catabolite repression, and catabolite repression is reversed by the addition of cyclic adenosine 5'-monophosphate. Dsdase synthesis in strain FB4005 is partially independent of the cyclic adenosine 5'-monophosphate binding protein, as constitutive synthesis is reduced only 65% (relative to the cap+ strain) in strains unable to synthesize the cyclic adenosine 5'-monophosphate binding protein. Surprisingly, the constitutive rate of Dsdase synthesis is fourfold higher in all mutants of both classes than in the parent, indicating a close interrelationship between the sites of response to induction and catabolite repression.
mesh_terms: D002874:Chromosome Mapping; D000242:Cyclic AMP / Q000378:metabolism; D004790:Enzyme Induction; D004794:Enzyme Repression; D004926:Escherichia coli / Q000201:enzymology* / Q000302:isolation & purification / Q000378:metabolism; D005696:Galactosidases / Q000096:biosynthesis / Q000378:metabolism; D005799:Genes, Dominant; D008040:Genetic Linkage; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D012695:L-Serine Dehydratase / Q000096:biosynthesis* / Q000378:metabolism; D009153:Mutagens; D009154:Mutation; D009604:Nitrosoguanidines; D010641:Phenotype; D011485:Protein Binding; D012694:Serine / Q000378:metabolism; D013237:Stereoisomerism; D013489:Suppression, Genetic; D014161:Transduction, Genetic
chemical_list: D009153:Mutagens; D009604:Nitrosoguanidines; D012694:Serine; D000242:Cyclic AMP; D005696:Galactosidases; D012695:L-Serine Dehydratase; D005947:Glucose; D005990:Glycerol