scholarly journals Dual Transcriptional Regulation of theEscherichia coli Phosphate-Starvation-InduciblepsiE Gene of the Phosphate Regulon by PhoB and the Cyclic AMP (cAMP)-cAMP Receptor Protein Complex

2000 ◽  
Vol 182 (19) ◽  
pp. 5596-5599 ◽  
Author(s):  
Soo-Ki Kim ◽  
Sigenobu Kimura ◽  
Hideo Shinagawa ◽  
Atsuo Nakata ◽  
Ki-Sung Lee ◽  
...  

ABSTRACT We have shown that the Escherichia coliphosphate-starvation-inducible psiE gene is regulated by both phosphate and the carbon source by using both lacZ and chloramphenicol acetyltransferase gene (cat) fusions. Yet, under all conditions tested, a single transcriptional start site lying 7 bp downstream of a predicted −10 region was revealed by primer extension analysis. DNase I footprinting showed that the PhoB transcriptional-activator protein protects two predictedpho boxes lying upstream of and near the −35 promoter region. Similar analysis showed that the cyclic AMP (cAMP)-cAMP receptor protein (cAMP-CRP) complex binds a region that overlaps with the downstream pho box. These results, together with measurements of the in vivo psiE promoter activity under various conditions, show that expression of the psiE gene is under direct positive and negative control by PhoB and cAMP-CRP, respectively.

1998 ◽  
Vol 180 (7) ◽  
pp. 1777-1785 ◽  
Author(s):  
Norbert Peekhaus ◽  
T. Conway

ABSTRACT The gntT gene of Escherichia coli is specifically induced by gluconate and repressed via catabolite repression. Thus, gluconate is both an inducer and a repressor ofgntT expression since gluconate is a catabolite-repressing sugar. In a gntR deletion mutant, the expression of a chromosomal gntT::lacZ fusion is both high and constitutive, confirming that GntR is the negative regulator of gntT. Indeed, GntR binds to two consensus gnt operator sites; one overlaps the −10 region of the gntT promoter, and the other is centered at +120 with respect to the transcriptional start site. The binding of GntR to these sites was proven in vitro by gel redardation assays and in vivo by site-directed mutagenesis of the binding sites. Binding of GntR to the operators is eliminated by gluconate and also by 6-phosphogluconate at a 10-fold-higher concentration. Interestingly, when gntR deletion strains are grown in the presence of gluconate, there is a twofold decrease in gntTexpression which is independent of catabolite repression and binding of GntR to the operator sites. This novel response of gntRmutants to the inducer is termed ultrarepression. Transcription ofgntT is activated by binding of the cyclic AMP (cAMP)-cAMP receptor protein (CRP) complex to a CRP binding site positioned at −71 upstream of the gntT transcription start site.


2008 ◽  
Vol 77 (2) ◽  
pp. 791-798 ◽  
Author(s):  
Maria D. Bodero ◽  
George P. Munson

ABSTRACT Enterotoxigenic Escherichia coli is a major cause of acute diarrheal illness worldwide and is responsible for high infant and child mortality rates in developing nations. Two types of enterotoxins, one heat labile and the other heat stable, are known to cause diarrhea. The expression of soluble heat-labile toxin is subject to catabolite (glucose) activation, and three binding sites for cAMP receptor protein (CRP or CAP) were identified upstream and within the toxin promoter by DNase I footprinting. One CRP operator is centered at −31.5, thus encompassing the promoter's −35 hexamer. Potassium permanganate footprinting revealed that the occupancy of this operator prevents RNA polymerase from forming an open complex in vitro. However, the operator centered at −31.5 is not sufficient for full repression in vivo because the deletion of the other two CRP binding sites partially relieved the CRP-dependent repression of the heat-labile toxin promoter. In contrast to heat-labile toxin, CRP positively regulates the expression of heat-stable toxin. Thus, the conditions for the optimal expression of one enterotoxin limit the expression of the other. Since glucose inhibits the activity of CRP by suppressing the pathogen's synthesis of cyclic AMP (cAMP), the concentration of glucose in the lumen of the small intestine may determine which enterotoxin is maximally expressed. In addition, our results suggest that the host may also modulate enterotoxin expression because cells intoxicated with heat-labile toxin overproduce and release cAMP.


Microbiology ◽  
2006 ◽  
Vol 152 (9) ◽  
pp. 2749-2756 ◽  
Author(s):  
Nisheeth Agarwal ◽  
Tirumalai R. Raghunand ◽  
William R. Bishai

The wbl (whiB-like) genes encode putative transcription factors unique to actinomycetes. This study characterized the promoter element of one of the seven wbl genes of Mycobacterium tuberculosis, whiB1 (Rv3219c). The results reveal that whiB1 is transcribed by a class I-type cAMP receptor protein (CRP)-dependent promoter, harbouring a CRP-binding site positioned at −58.5 with respect to its transcription start point. In vivo promoter activity analysis and electrophoretic mobility shift assays suggest that the expression of whiB1 is indeed regulated by cAMP-dependent binding of CRPM (encoded by the M. tuberculosis gene Rv3676) to the whiB1 5′ untranslated region (5′UTR). β-Galactosidase gene fusion analysis revealed induction of the whiB1 promoter in M. tuberculosis on addition of exogenous dibutyric cAMP (a diffusible cAMP analogue) only when an intact CRP-binding site was present. These results indicate that M. tuberculosis whiB1 transcription is regulated in part by cAMP levels via direct binding of cAMP-activated CRPM to a consensus CRP-binding site in the whiB1 5′UTR.


1991 ◽  
Vol 173 (17) ◽  
pp. 5419-5430 ◽  
Author(s):  
P Gerlach ◽  
L Søgaard-Andersen ◽  
H Pedersen ◽  
J Martinussen ◽  
P Valentin-Hansen ◽  
...  

2004 ◽  
Vol 186 (6) ◽  
pp. 1893-1897 ◽  
Author(s):  
A. Derouaux ◽  
S. Halici ◽  
H. Nothaft ◽  
T. Neutelings ◽  
G. Moutzourelis ◽  
...  

ABSTRACT Open reading frame SCO3571 of Streptomyces coelicolor encodes a protein of the cyclic AMP (cAMP) receptor protein (CRP) superfamily of regulatory proteins. A mutant revealed a dramatic defect in germination, followed by growth delay and earlier sporulation. This phenotype correlates with those of an adenylate cyclase (cya) mutant that cannot synthesize cAMP. This finding suggests that S. coelicolor may use a Cya-cAMP-CRP system to trigger complex physiological processes such as morphogenesis.


PLoS ONE ◽  
2015 ◽  
Vol 10 (9) ◽  
pp. e0137529 ◽  
Author(s):  
M. Shamim Hasan Zahid ◽  
Sharda Prasad Awasthi ◽  
Masahiro Asakura ◽  
Shruti Chatterjee ◽  
Atsushi Hinenoya ◽  
...  

2021 ◽  
Vol 12 ◽  
Author(s):  
Laura Meyer ◽  
Elsa Germain ◽  
Etienne Maisonneuve

Guanosine penta- or tetraphosphate (known as (p)ppGpp) serves as second messenger to respond to nutrient downshift and other environmental stresses, a phenomenon called stringent response. Accumulation of (p)ppGpp promotes the coordinated inhibition of macromolecule synthesis, as well as the activation of stress response pathways to cope and adapt to harmful conditions. In Escherichia coli, the (p)ppGpp level is tightly regulated by two enzymes, the (p)ppGpp synthetase RelA and the bifunctional synthetase/hydrolase SpoT. We recently identified the small protein YtfK as a key regulator of SpoT-mediated activation of stringent response in E. coli. Here, we further characterized the regulation of ytfK. We observed that ytfK is subjected to catabolite repression and is positively regulated by the cyclic AMP (cAMP)-cAMP receptor protein (CRP) complex. Importantly, YtfK contributes to SpoT-dependent accumulation of (p)ppGpp and cell survival in response to glucose starvation. Therefore, regulation of ytfK by the cAMP-CRP appears important to adjust (p)ppGpp level and coordinate cellular metabolism in response to glucose availability.


1999 ◽  
Vol 181 (2) ◽  
pp. 689-694 ◽  
Author(s):  
Kyeong R. Park ◽  
Jean-Christophe Giard ◽  
Juno H. Eom ◽  
Shawn Bearson ◽  
John W. Foster

ABSTRACT Two acid-inducible genes, aniC and aciK, that require anaerobiosis and tyrosine for expression were identified as orf326a encoding a potential amino acid/polyamine antiporter and hyaB encoding hydrogenase I, respectively. Cyclic AMP (cAMP) receptor protein, cAMP, and TyrR, regulator of aromatic amino acid metabolism, were strong positive regulators of both genes.


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