title: Biochemical and genetic characterization of a carbamyl phosphate synthetase mutant of Escherichia coli K12.
abstract: An unusual Escherichia coli K12 mutant for carbamyl phosphate synthetase is described. The mutation was generated by bacteriophage MUI insertion and left a 5% residual activity of the enzyme using either ammonia or glutamine as donors. The mutation is recessive to the wild-type allele and maps at or near the pyrA gene, but the mutant requires only arginine and not uracil for growth. By a second block in the pyrB gene it was possible to shift the accumulated carbamyl phosphate to arginine biosynthesis. The Km values and the levels of ornithine activation and inhibition by UMP were normal in the mutant enzyme.
mesh_terms: D000641:Ammonia / Q000378:metabolism; D001120:Arginine / Q000378:metabolism; D002222:Carbamoyl-Phosphate Synthase (Ammonia) / Q000378:metabolism; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing) / Q000378:metabolism; D002221:Carbamyl Phosphate / Q000378:metabolism; D002474:Cell-Free System; D003090:Coliphages / Q000254:growth & development; D004926:Escherichia coli / Q000201:enzymology* / Q000378:metabolism; D005808:Genes, Recessive; D005973:Glutamine / Q000378:metabolism; D009153:Mutagens; D009154:Mutation; D009604:Nitrosoguanidines; D009952:Ornithine / Q000494:pharmacology; D009954:Ornithine Carbamoyltransferase / Q000378:metabolism; D010770:Phosphotransferases / Q000096:biosynthesis*; D014161:Transduction, Genetic; D014500:Uracil Nucleotides / Q000494:pharmacology
chemical_list: D009153:Mutagens; D009604:Nitrosoguanidines; D014500:Uracil Nucleotides; D005973:Glutamine; D002221:Carbamyl Phosphate; D000641:Ammonia; D001120:Arginine; D009952:Ornithine; D009954:Ornithine Carbamoyltransferase; D010770:Phosphotransferases; D002222:Carbamoyl-Phosphate Synthase (Ammonia); D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing)