Previous Article | Next Article ![]()
Journal of Bacteriology, December 1998, p. 6476-6483, Vol. 180, No. 24
Maturation des ARN et Enzymologie
Moléculaire, UMR CNRS 7567, Université H. Poincaré,
Faculté des Sciences, 54506 Vandoeuvre-les-Nancy, Cedex, France
Received 28 July 1998/Accepted 14 October 1998
The Escherichia coli gapB gene codes for a protein that
is very similar to bacterial glyceraldehyde-3-phosphate dehydrogenases (GAPDH). In most bacteria, the gene for GAPDH is located upstream of
the pgk gene encoding 3-phosphoglycerate kinase (PGK). This is the case for gapB. However, this gene is poorly
expressed and encodes a protein with an erythrose 4-phosphate
dehydrogenase activity (E4PDH). The active GAPDH is encoded by the
gapA gene. Since we found that the nucleotide region
upstream of the gapB open reading frame is responsible for
part of the PGK production, we analyzed gapB promoter
activity in vivo by direct measurement of the mRNA levels by reverse
transcription. We showed the presence of a unique transcription
promoter, gapB P0, with a cyclic AMP (cAMP) receptor
protein (CRP)-cAMP binding site centered 70.5 bp upstream of the start
site. Interestingly, the gapB P0 promoter activity was
strongly enhanced when glucose was used as the carbon source. In these
conditions, deletion of the CRP-cAMP binding site had little effect on
promoter gapB P0 activity. In contrast, abolition of CRP
production or of cAMP biosynthesis (crp or cya mutant strains) strongly reduced promoter gapB P0 activity.
This suggests that in the presence of glucose, the CRP-cAMP complex has
an indirect effect on promoter gapB P0 activity. We also
showed that glucose stimulation of gapB P0 promoter
activity depends on the expression of enzyme IIGlc
(EIIGlc), encoded by the ptsG gene, and that
the gapA P1 promoter is also activated by glucose via the
EIIGlc protein. A similar glucose-mediated activation,
dependent on the EIIGlc protein, was described by others
for the pts operon. Altogether, this shows that when
glucose is present in the growth medium expression of the E. coli genes required for its uptake (pts) and its
metabolism (gapA and gapB-pgk) are coordinately
activated by a mechanism dependent upon the EIIGlc protein.
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
The EIIGlc Protein Is Involved in
Glucose-Mediated Activation of Escherichia coli gapA and
gapB-pgk Transcription
*
Corresponding author. Mailing address: Maturation des
ARN et Enzymologie Moléculaire, UMR CNRS 7567, Université
H. Poincaré, Faculté des Sciences, BP 239, 54506 Vandoeuvre-les-Nancy, Cedex, France. Phone: (33) 3 83 91 20 91. Fax:
(33) 3 83 91 20 93. E-mail: cbranlant{at}scbim.u-nancy.fr.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»