Repression of the gene encoding succinate dehydrogenase in response to glucose is mediated by the EIICB(Glc) protein in Escherichia coli.
The Escherichia coli sdhCDAB operon encodes succinate dehydrogenase, an enzyme complex involved in the tricarboxylic acid (TCA) cycle. Expression of this operon is under complex transcriptional regulation in response to growth conditions, such as anaerobiosis and carbon sources. Typically, the expression of sdhCDAB is known to be subjected to "an aerobic repression" and "a glucose repression." The molecular mechanism underlying the anaerobic repression has been well documented, involving both the ArcB-ArcA two-component system and the Fnr global anaerobic regulator. However, the mechanism underlying the glucose repression is not yet clear, because the involvement of the general catabolite regulators such as CRP and CRA has been dismissed. In this study, we conducted a series of genetic analyses to identify the regulator gene(s) involved in the glucose repression of sdh. The results demonstrate that the EIICB(Glc) protein (the ptsG gene product), a component of the major glucose transporter, acts as a crucial mediator in glucose repression. These results support the view that the EIICB(Glc) protein functions not only as a glucose transporter, but also as a glucose-sensing signal transducer that modulates the glucose repression of the sdhCDAB operon.
Takeda
S
S
Laboratory of Molecular Microbiology, School of Agriculture, Nagoya University, Chikusa-ku, Nagoya, 464-8601, Japan.
Matsushika
A
A
Mizuno
T
T
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000378:metabolism; D002876:Chromosomes, Bacterial / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D005947:Glucose / Q000378:metabolism*; D007763:Lac Operon; D008565:Membrane Proteins / Q000378:metabolism; D008954:Models, Biological; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000235:genetics* / Q000502:physiology*; D011494:Protein Kinases; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D015398:Signal Transduction; D013385:Succinate Dehydrogenase / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000378:metabolism
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; C111065:Mlc protein, E coli; D009004:Monosaccharide Transport Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D013385:Succinate Dehydrogenase; D011494:Protein Kinases; C065271:arcB protein, E coli; D001616:beta-Galactosidase; D005947:Glucose