title: Expression of the arginine regulon of Escherichia coli W: evidence for a second regulatory gene.
abstract: Effect of the M (modifier) gene of Escherichia coli W on the expression of wild-type structural genes of four arginine biosynthetic enzymes was studied by examining enzyme activity in cell-free extracts of cultures grown in minimal medium and medium containing arginine. The mutant M gene was originally identified as causing arginine-induced synthesis of acetylornithine delta-transaminase in a strain deficient for the enzyme. The strains used in this study received the mutant M gene by recombination. Noncoordinate repression has been demonstrated for two more enzymes of the arginine regulon of E. coli W and the M(-) gene increases the degree of noncoordinate repression for the regulon. Mutation of the M gene results in altered regulation of acetylornithine delta-transaminase, ornithine transcarbamylase, and acetylornithinase. In addition, a decreased growth rate is observed. It is proposed that the M gene is a regulatory gene. A model is presented to explain the data which involves changes in operator-repressor affinity for the structural genes and possibly for the gene controlling arginyl transfer ribonucleic acid synthetase.
mesh_terms: D000581:Amidohydrolases / Q000378:metabolism; D001120:Arginine / Q000096:biosynthesis*; D004794:Enzyme Repression; D004926:Escherichia coli / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism; D005796:Genes; D005809:Genes, Regulator; D008190:Lyases / Q000378:metabolism; D008967:Molecular Biology; D009154:Mutation; D009954:Ornithine Carbamoyltransferase / Q000378:metabolism; D000637:Transaminases / Q000378:metabolism
chemical_list: D001120:Arginine; D009954:Ornithine Carbamoyltransferase; D000637:Transaminases; D000581:Amidohydrolases; D008190:Lyases