Expression of Escherichia coli pyruvate oxidase (PoxB) depends on the sigma factor encoded by the rpoS(katF) gene.
The activity of Escherichia coli pyruvate oxidase (PoxB) was shown to be growth-phase dependent; the enzyme activity reaches a maximum at early stationary phase. We report that PoxB activity is dependent on a functional rpoS(katF) gene which encodes a sigma factor required to transcribe a number of stationary-phase-induced genes. PoxB activity as well as the beta-galactosidase encoded by a poxB::lacZ protein fusion was completely abolished in a strain containing a defective rpoS gene. Northern and primer extension analyses showed that poxB expression was regulated at the transcriptional level and was transcribed from a single promoter; the 5' end of the mRNA being located 27 bp upstream of the translational initiation codon of poxB. The poxB gene was expressed at decreased levels under anaerobiosis; however, the anaerobic regulatory genes arcA, arcB or fnr were not involved in anaerobic poxB gene expression. Expression of the rpoS(katF) gene has been reported to be affected by acetate, the product of PoxB reaction. However, we found that poxB null mutations had no effect on rpoS(katF) expression. Inactivation of two genes involved in acetate metabolism, ackA and pta, had no effect on either poxB or rpoS(katF) expression.
Department of Microbiology, University of Illinois, Urbana 61801.
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Chang
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Wang
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D000332:Aerobiosis / Q000502:physiology; D000595:Amino Acid Sequence; D000693:Anaerobiosis / Q000502:physiology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D005798:Genes, Bacterial; D007506:Iron-Sulfur Proteins; D008565:Membrane Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic / Q000235:genetics; D011494:Protein Kinases; D011771:Pyruvate Oxidase / Q000096:biosynthesis / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins; D012808:Sigma Factor / Q000378:metabolism*; D014158:Transcription, Genetic
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C060704:FNR protein, E coli; D007506:Iron-Sulfur Proteins; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D012808:Sigma Factor; C041610:arcA protein, E coli; C069567:sigma factor KatF protein, Bacteria; D011771:Pyruvate Oxidase; D011494:Protein Kinases; C065271:arcB protein, E coli