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Divergent transcription of the argECBH cluster of Escherichia coli K12. Mutations which alter the control of enzyme synthesis

1976; Elsevier BV; Volume: 102; Issue: 2 Linguagem: Inglês

10.1016/s0022-2836(76)80049-6

1089-8638

Anthony Bretscher, S. Baumberg,

RNA and protein synthesis mechanisms

A method is described for the selection of mutants with altered control of argE expression. Three mutations were characterized and mapped. The first, lying in argH, results in a partially functional enzyme and so limits the supply of arginine for repression. The second, the promoter mutation arg8, confers in creased expression of argE and reduced expression of argCBH, although the wild type repression ratios are retained. The third, the operator mutation arg11, leads to non-repressible expression of argE and reduced repressibility of argCBH expression. The effects of all three mutations are cluster specific. Arg8 and arg11 are dominant mutations and do not result from genetic duplication. These two mutations map close to, or at, the argE-argC boundary; arg8 lies between argE and arg11. The properties of these mutations support previous conclusions that the cluster is transcribed divergently from the argE-argC boundary.