scholarly journals A cAMP-independent carbohydrate-driven mechanism inhibits tnaA expression and TnaA enzyme activity in Escherichia coli

Microbiology ◽  
2014 ◽  
Vol 160 (9) ◽  
pp. 2079-2088 ◽  
Author(s):  
Gang Li ◽  
Kevin D. Young
Keyword(s):  
Escherichia Coli ◽  
Enzyme Activity ◽  
Receptor Protein ◽  
Intracellular Camp ◽  
Camp Receptor Protein ◽  
Additional Mechanism ◽  
E Coli ◽  
Tolc Protein ◽  
Camp Receptor ◽  
Camp Levels

When Escherichia coli is grown in a medium lacking glucose or another preferred carbohydrate, the concentration of cAMP–cAMP receptor protein (cAMP–CRP) increases, and this latter complex regulates the expression of more than 180 genes. To respond rapidly to changes in carbohydrate availability, E. coli must maintain a suitable intracellular concentration of cAMP by either exporting or degrading excess cAMP. Currently, cAMP export via the TolC protein is thought to be more efficient at reducing these levels than is CpdA-mediated degradation of cAMP. Here, we compared the contributions of TolC and CpdA by measuring the expression of cAMP-regulated genes that encode tryptophanase (TnaA) and β-galactosidase. In the presence of exogenous cAMP, a tolC mutant produced intermediate levels of these enzymes, suggesting that cAMP levels were held in check by CpdA. Conversely, a cpdA mutant produced much higher amounts of these enzymes, indicating that CpdA was more efficient than TolC at reducing cAMP levels. Surprisingly, expression of the tnaA gene halted rapidly when glucose was added to cells lacking both TolC and CpdA, even though under these conditions cAMP could not be removed by either pathway and tnaA expression should have remained high. This result suggests the existence of an additional mechanism that eliminates intracellular cAMP or terminates expression of some cAMP–CRP-regulated genes. In addition, adding glucose and other carbohydrates rapidly inhibited the function of pre-formed TnaA, indicating that TnaA is regulated by a previously unknown carbohydrate-dependent post-translational mechanism.

Determination of the rates of synthesis and degradation of adenosine 3′,5′-cyclic monophosphate in Escherichia coli CRP− and CRP+ strains

1978 ◽  
Vol 56 (9) ◽  
pp. 849-852 ◽  
Author(s):  
Ann D. E. Fraser ◽  
Hiroshi Yamazaki
Keyword(s):  
Escherichia Coli ◽  
Receptor Protein ◽  
Camp Receptor Protein ◽  
Balanced Growth ◽  
E Coli ◽  
Cyclic Monophosphate ◽  
Camp Receptor ◽  
Extracellular Camp ◽  
Synthesis And Degradation

We have developed a method for estimating the rates of synthesis and degradation of adenosine 3′,5′-cyclic monophosphate (cAMP) in Escherichia coli during balanced growth. Applying this method, we have found that an E. coli CRP− mutant 5333 (deficient for cAMP receptor protein) synthesizes cAMP about 25 times faster than does its CRP+ parent 1100. This accounts for the abnormally high intracellular and extracellular cAMP accumulation in 5333.

scholarly journals Regulation of ytfK by cAMP-CRP Contributes to SpoT-Dependent Accumulation of (p)ppGpp in Response to Carbon Starvation YtfK Responds to Glucose Exhaustion

2021 ◽  
Vol 12 ◽  
Author(s):  
Laura Meyer ◽  
Elsa Germain ◽  
Etienne Maisonneuve
Keyword(s):  
Escherichia Coli ◽  
Cyclic Amp ◽  
Catabolite Repression ◽  
Stringent Response ◽  
Receptor Protein ◽  
Glucose Starvation ◽  
Camp Receptor Protein ◽  
E Coli ◽  
Camp Receptor ◽  
Glucose Availability

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.

scholarly journals Studies of the distribution of Escherichia coli cAMP-receptor protein and RNA polymerase along the E. coli chromosome

2005 ◽  
Vol 102 (49) ◽  
pp. 17693-17698 ◽  
Author(s):  
D. C. Grainger ◽  
D. Hurd ◽  
M. Harrison ◽  
J. Holdstock ◽  
S. J. W. Busby
Keyword(s):  
Escherichia Coli ◽  
Rna Polymerase ◽  
Receptor Protein ◽  
Camp Receptor Protein ◽  
E Coli ◽  
Camp Receptor

scholarly journals Positive Effect of Carbon Sources on Natural Transformation in Escherichia coli: Role of Low-Level Cyclic AMP (cAMP)-cAMP Receptor Protein in the Derepression ofrpoS

2015 ◽  
Vol 197 (20) ◽  
pp. 3317-3328 ◽  
Author(s):  
Mengyue Guo ◽  
Huanyu Wang ◽  
Nengbin Xie ◽  
Zhixiong Xie
Keyword(s):  
Escherichia Coli ◽  
Natural Transformation ◽  
Carbon Sources ◽  
Transformation Frequency ◽  
Receptor Protein ◽  
Camp Receptor Protein ◽  
Content Type ◽  
E Coli ◽  
Camp Receptor

ABSTRACTNatural plasmid transformation ofEscherichia coliis a complex process that occurs strictly on agar plates and requires the global stress response factor σS. Here, we showed that additional carbon sources could significantly enhance the transformability ofE. coli. Inactivation of phosphotransferase system genes (ptsH,ptsG, andcrr) caused an increase in the transformation frequency, and the addition of cyclic AMP (cAMP) neutralized the promotional effect of carbon sources. This implies a negative role of cAMP in natural transformation. Further study showed thatcrpandcyaAmutations conferred a higher transformation frequency, suggesting that the cAMP-cAMP receptor protein (CRP) complex has an inhibitory effect on transformation. Moreover, we observed thatrpoSis negatively regulated by cAMP-CRP in early log phase and that bothcrpandcyaAmutants show no transformation superiority whenrpoSis knocked out. Therefore, it can be concluded that both thecrpandcyaAmutations derepressrpoSexpression in early log phase, whereby they aid in the promotion of natural transformation ability. We also showed that the accumulation of RpoS during early log phase can account for the enhanced transformation aroused by additional carbon sources. Our results thus demonstrated that the presence of additional carbon sources promotes competence development and natural transformation by reducing cAMP-CRP and, thus, derepressingrpoSexpression during log phase. This finding could contribute to a better understanding of the relationship between nutrition state and competence, as well as the mechanism of natural plasmid transformation inE. coli.IMPORTANCEEscherichia coli, which is not usually considered to be naturally transformable, was found to spontaneously take up plasmid DNA on agar plates. Researching the mechanism of natural transformation is important for understanding the role of transformation in evolution, as well as in the transfer of pathogenicity and antibiotic resistance genes. In this work, we found that carbon sources significantly improve transformation by decreasing cAMP. Then, the low level of cAMP-CRP derepresses the general stress response regulator RpoS via a biphasic regulatory pattern, thereby contributing to transformation. Thus, we demonstrate the mechanism by which carbon sources affect natural transformation, which is important for revealing information about the interplay between nutrition state and competence development inE. coli.

scholarly journals N-Acetyl-d-Glucosamine Induces the Expression of Multidrug Exporter Genes, mdtEF, via Catabolite Activation in Escherichia coli

2006 ◽  
Vol 188 (16) ◽  
pp. 5851-5858 ◽  
Author(s):  
Hidetada Hirakawa ◽  
Yoshihiko Inazumi ◽  
Yasuko Senda ◽  
Asuka Kobayashi ◽  
Takahiro Hirata ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Signaling Pathways ◽  
Protein Gene ◽  
The Other ◽  
Receptor Protein ◽  
Camp Receptor Protein ◽  
Gene Encoding ◽  
E Coli ◽  
Camp Receptor ◽  
Multiple Signaling

ABSTRACT The expression of MdtEF, a multidrug exporter in Escherichia coli, is positively controlled through multiple signaling pathways, but little is known about signals that induce MdtEF expression. In this study, we investigated compounds that induce the expression of the mdtEF genes and found that out of 20 drug exporter genes in E. coli, the expression of mdtEF is greatly induced by N-acetyl-d-glucosamine (GlcNAc). The induction of mdtEF by GlcNAc is not mediated by the evgSA, ydeO, gadX, and rpoS signaling pathways that have been known to regulate mdtEF expression. On the other hand, deletion of the nagE gene, encoding the phosphotransferase (PTS) system for GlcNAc, prevented induction by GlcNAc. The induction of mdtEF by GlcNAc was also greatly inhibited by the addition of cyclic AMP (cAMP) and completely abolished upon deletion of the cAMP receptor protein gene (crp). Other PTS sugars, glucose and d-glucosamine, also induced mdtEF gene expression. These results suggest that mdtEF expression is stimulated through catabolite control.

scholarly journals Characterization of DNA-binding specificity and analysis of binding sites of the Pseudomonas aeruginosa global regulator, Vfr, a homologue of the Escherichia coli cAMP receptor protein

Microbiology ◽  
2006 ◽  
Vol 152 (12) ◽  
pp. 3485-3496 ◽  
Author(s):  
Kristen J. Kanack ◽  
Laura J. Runyen-Janecky ◽  
Evan P. Ferrell ◽  
Sang-Jin Suh ◽  
Susan E. H. West
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Receptor Protein ◽  
Camp Receptor Protein ◽  
Global Regulator ◽  
E Coli ◽  
Consensus Binding Sequence ◽  
Target Sequences ◽  
Camp Receptor ◽  
Binding Sequence

Vfr, a global regulator of Pseudomonas aeruginosa virulence factors, is a homologue of the Escherichia coli cAMP receptor protein, CRP. Vfr is 91 % similar to CRP and maintains many residues important for CRP to bind cAMP, bind DNA, and interact with RNA polymerase at target promoters. While vfr can complement an E. coli crp mutant in β-galactosidase production, tryptophanase production and catabolite repression, crp can only complement a subset of Vfr-dependent phenotypes in P. aeruginosa. Using specific CRP binding site mutations, it is shown that Vfr requires the same nucleotides as CRP for optimal transcriptional activity from the E. coli lac promoter. In contrast, CRP did not bind Vfr target sequences in the promoters of the toxA and regA genes. Footprinting analysis revealed Vfr protected sequences upstream of toxA, regA, and the quorum sensing regulator lasR, that are similar to but significantly divergent from the CRP consensus binding sequence, and Vfr causes similar DNA bending to CRP in bound target sequences. Using a preliminary Vfr consensus binding sequence deduced from the Vfr-protected sites, Vfr target sequences were identified upstream of the virulence-associated genes plcN, plcHR, pbpG, prpL and algD, and in the vfr/orfX, argH/fimS, pilM/ponA intergenic regions. From these sequences the Vfr consensus binding sequence, 5′-ANWWTGNGAWNY : AGWTCACAT-3′, was formulated. This study suggests that Vfr shares many of the same functions as CRP, but has specialized functions, at least in terms of DNA target sequence binding, required for regulation of a subset of genes in its regulon.

Sign in / Sign up

Export Citation Format

Share Document