title: Regulation of argA operon expression in Escherichia coli K-12: cell-free synthesis of beta-galactosidase under argA control.
abstract: Regulation of argA operon expression in Escherichia coli K-12 was studied in a cell-free, deoxyribonucleic acid-dependent, enzyme-synthesizing system. lambdaAZ-7 deoxyribonucleic acid, which carries a fusion of the lacZ structural gene to the argA operon so that beta-galactosidase synthesis is under argA regulation, was used as the template. To eliminate extraneous readthrough from lambda promoters, lambda repressor was introduced into the synthesis mixtures by preparing the S-30 component from a strain (514X5a-12-29) that carries a multicopy hybrid plasmid (pKB252) containing the lambdacI gene. Under these conditions beta-galactosidase synthesis was repressed 90% by the arginine repressor when a sufficient concentration of L-arginine was present. This repression could be overcome by escape synthesis when the lambdaAZ-7 deoxyribonucleic acid concentration in the synthesis mixtures was increased. Guanosine 3'-diphosphate-5'-diphosphate stimulated beta-galactosidase synthesis from this template.
mesh_terms: D001120:Arginine / Q000096:biosynthesis / Q000235:genetics*; D002474:Cell-Free System; D003090:Coliphages / Q000235:genetics; D004279:DNA, Viral / Q000235:genetics; D004794:Enzyme Repression; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D005696:Galactosidases / Q000235:genetics*; D005809:Genes, Regulator; D009876:Operon; D013698:Templates, Genetic; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D004279:DNA, Viral; D001120:Arginine; D005696:Galactosidases; D001616:beta-Galactosidase