Isolation and identification of mutants constitutive for aspartokinase III synthesis in Escherichia coli K 12.
We devised a procedure in order to isolate, in Escherichia coli, constitutive mutants for aspartokinase III synthesis, the first enzyme of the lysine regulon. It consists of the introduction of a limiting step in lysine biosynthesis, by the use of the partial suppression of a nonsense mutation. For the first time we could isolate many constitutive mutants. Their characteristics (cotransduction with the lysC structural gene; no effect on the synthesis of other enzymes of the regulon; cis-dominance) lead to classify these mutations as operator-type. The fact that no repressor mutations could be isolated is discussed.
D001222:Aspartate Kinase / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D008239:Lysine / Q000494:pharmacology; D009154:Mutation; D010770:Phosphotransferases / Q000235:genetics*; D013045:Species Specificity; D014161:Transduction, Genetic
D010770:Phosphotransferases; D001222:Aspartate Kinase; D008239:Lysine