Regulation of microcin C51 operon expression: the role of global regulators of transcription.
Expression of the microcin C51 operon in Escherichia coli cells is regulated as a function of the phase of growth; it is stimulated during the decelerating phase of growth. Using single-copy P(mcc)-lac transcriptional fusion (the promoter region of the microcin C51 operon fused to a promoterless lac operon in lambda phage), we showed that transcription from the microcin operon promoter is dependent on sigma(s) (RpoS) factor. However, some level of P(mcc)-lac expression is possible in rpoS null mutants, indicating that another sigma factor might be involved in transcription of the microcin C51 operon. Overproduction of sigma70 decreased Pmcc-directed transcription, presumably as a result of competition of sigma factors for the limited amount of core RNA polymerase. The cyclic AMP-CRP complex was shown to stimulate transcription from Pmcc: the absence of CRP or cAMP in crp or cya mutant cells strongly decreased the level of P(mcc)-lac expression. The production of C51 microcin decreased or was absent in rpoS, crp and cya mutant cells. Leucine-responsive protein Lrp and histone-like protein H-NS repressed P(mcc)-lac expression in the exponential and decelerating phases of growth. In studies of P(mcc)-lac expression in double mutant cells, we showed that proteins CRP, Lrp and H-NS acted in rpoS-dependent and rpoS-independent ways in transcription of the microcin C51 operon. Mutation hns(-) resulted in an increase in P(mcc)-lac expression in crp, rpoS and lrp mutant cells, as in wild-type cells.
Fomenko
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D
Institute of Molecular Genetics, Russian Academy of Sciences, Moscow.
Veselovskii
A
A
Khmel
I
I
D001426:Bacterial Proteins / Q000378:metabolism; D001430:Bacteriocins / Q000235:genetics*; D001483:Base Sequence; D002352:Carrier Proteins; D003001:Cloning, Molecular; D002373:Cyclic AMP Receptor Protein / Q000378:metabolism; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins / Q000378:metabolism; D029721:Drosophila Proteins; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D007763:Lac Operon; D051756:Leucine-Responsive Regulatory Protein; D008969:Molecular Sequence Data; D009154:Mutation; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D009876:Operon; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic; D012808:Sigma Factor / Q000378:metabolism; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000235:genetics; D001616:beta-Galactosidase / Q000096:biosynthesis
D001426:Bacterial Proteins; D001430:Bacteriocins; D002352:Carrier Proteins; D002373:Cyclic AMP Receptor Protein; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D029968:Escherichia coli Proteins; C031908:H-NS protein, bacteria; C497278:Lrp protein, E coli; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D012808:Sigma Factor; D014157:Transcription Factors; C073099:pros protein, Drosophila; C069567:sigma factor KatF protein, Bacteria; D051756:Leucine-Responsive Regulatory Protein; C020411:microcin; D001616:beta-Galactosidase