scholarly journals The KdpD Sensor Kinase of Escherichia coli Responds to Several Distinct Signals To Turn on Expression of the Kdp Transport System

2015 ◽  
Vol 198 (2) ◽  
pp. 212-220 ◽  
Author(s):  
Wolfgang Epstein
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Transport System ◽  
Kinase Activity ◽  
Response Regulator ◽  
Sensor Kinase ◽  
Monovalent Cations ◽  
Two Component System ◽  
Content Type ◽  
E Coli

ABSTRACTKdp, one of three saturable K+uptake systems inEscherichia coli, is the system with the highest affinity for K+and the only one whose expression is strongly controlled by medium K+concentration. Expression is controlled by a two-component system of KdpD, the sensor kinase, and KdpE, the response regulator. There is general agreement that expression occurs when the growth rate of cells begins to become limited by K+availability. How K+limitation results in expression has been controversial. Studying the roles of the major components of the growth medium shows that KdpD senses at least two distinct signals inside the cell, those of Na+and NH4+, and it probably senses other monovalent cations in the cell. KdpD does not sense turgor.IMPORTANCEThe expression of the Kdp K+transport system ofE. colioccurs when cells become limited in their growth rate by the availability of K+. Cells sense limited K+and try to compensate by taking up other monovalent cations, particularly Na+and NH4+. These cations are sensed in the cytoplasm by the KdpD response regulator, presumably to stimulate its kinase activity. It is shown that KdpD does not sense turgor, as was suggested earlier.

scholarly journals Molecular Control of Sucrose Utilization in Escherichia coli W, an Efficient Sucrose-Utilizing Strain

2012 ◽  
Vol 79 (2) ◽  
pp. 478-487 ◽  
Author(s):  
Suriana Sabri ◽  
Lars K. Nielsen ◽  
Claudia E. Vickers
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Good Growth ◽  
Knockout Mutant ◽  
Sucrose Transport ◽  
Molecular Control ◽  
Content Type ◽  
E Coli ◽  
K 12 ◽  
Sucrose Utilization

ABSTRACTSucrose is an industrially important carbon source for microbial fermentation. Sucrose utilization inEscherichia coli, however, is poorly understood, and most industrial strains cannot utilize sucrose. The roles of the chromosomally encoded sucrose catabolism (csc) genes inE. coliW were examined by knockout and overexpression experiments. At low sucrose concentrations, thecscgenes are repressed and cells cannot grow. Removal of either the repressor protein (cscR) or the fructokinase (cscK) gene facilitated derepression. Furthermore, combinatorial knockout ofcscRandcscKconferred an improved growth rate on low sucrose. The invertase (cscA) and sucrose transporter (cscB) genes are essential for sucrose catabolism inE. coliW, demonstrating that no other genes can provide sucrose transport or inversion activities. However,cscKis not essential for sucrose utilization. Fructose is excreted into the medium by thecscK-knockout strain in the presence of high sucrose, whereas at low sucrose (when carbon availability is limiting), fructose is utilized by the cell. Overexpression ofcscA,cscAK, orcscABcould complement the WΔcscRKABknockout mutant or confer growth on a K-12 strain which could not naturally utilize sucrose. However, phenotypic stability and relatively good growth rates were observed in the K-12 strain only when overexpressingcscAB, and full growth rate complementation in WΔcscRKABalso requiredcscAB. Our understanding of sucrose utilization can be used to improveE. coliW and engineer sucrose utilization in strains which do not naturally utilize sucrose, allowing substitution of sucrose for other, less desirable carbon sources in industrial fermentations.

scholarly journals Fitness, Stress Resistance, and Extraintestinal Virulence in Escherichia coli

2013 ◽  
Vol 81 (8) ◽  
pp. 2733-2742 ◽  
Author(s):  
Alexandre Bleibtreu ◽  
Pierre-Alexis Gros ◽  
Cédric Laouénan ◽  
Olivier Clermont ◽  
Hervé Le Nagard ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Stress Response ◽  
Mouse Model ◽  
Stress Resistance ◽  
Maximum Growth ◽  
Competitive Fitness ◽  
Content Type ◽  
General Stress Response ◽  
E Coli

ABSTRACTThe extraintestinal virulence ofEscherichia coliis dependent on numerous virulence genes. However, there is growing evidence for a role of the metabolic properties and stress responses of strains in pathogenesis. We assessed the respective roles of these factors in strain virulence by developing phenotypic assays for measuringin vitroindividual and competitive fitness and the general stress response, which we applied to 82 commensal and extraintestinal pathogenicE. colistrains previously tested in a mouse model of sepsis. Individual fitness properties, in terms of maximum growth rates in various media (Luria-Bertani broth with and without iron chelator, minimal medium supplemented with gluconate, and human urine) and competitive fitness properties, estimated as the mean relative growth rate per generation in mixed cultures with a reference fluorescentE. colistrain, were highly diverse between strains. The activity of the main general stress response regulator, RpoS, as determined by iodine staining of the colonies, H2O2resistance, andrpoSsequencing, was also highly variable. No correlation between strain fitness and stress resistance and virulence in the mouse model was found, except that the maximum growth rate in urine was higher for virulent strains. Multivariate analysis showed that the number of virulence factors was the only independent factor explaining the virulence in mice. At the species level, growth capacity and stress resistance are heterogeneous properties that do not contribute significantly to the intrinsic virulence of the strains.

scholarly journals Biochemical Activities of the absA Two-Component System of Streptomyces coelicolor

2005 ◽  
Vol 187 (2) ◽  
pp. 687-696 ◽  
Author(s):  
Nancy L. Sheeler ◽  
Susan V. MacMillan ◽  
Justin R. Nodwell
Keyword(s):  
Transcriptional Repression ◽  
Kinase Activity ◽  
Response Regulator ◽  
Streptomyces Coelicolor ◽  
Point Mutations ◽  
Stable State ◽  
Sensor Kinase ◽  
Two Component System ◽  
Antibiotic Synthesis ◽  
Cognate Response Regulator

ABSTRACT The AbsA1 sensor kinase and its cognate response regulator AbsA2 are important regulators of antibiotic synthesis in Streptomyces coelicolor. While certain point mutations in absA1 reduce or eliminate the synthesis of several antibiotics, null mutations in these genes bring about enhanced antibiotic synthesis. We show here that AbsA1, which is unusual in sequence and structure, is both an AbsA2 kinase and an AbsA2∼P phosphatase. The half-life of AbsA2∼P in solution is 68.6 min, consistent with a role in maintaining a relatively stable state of transcriptional repression or activation. We find that mutations in the absA locus that enhance antibiotic synthesis impair AbsA2 kinase activity and that mutations that repress antibiotic synthesis impair AbsA2∼P phosphatase activity. These results support a model in which the phosphorylation state of AbsA2 is determined by the balance of the kinase and phosphatase activities of AbsA1 and where AbsA2∼P represses antibiotic biosynthetic genes either directly or indirectly.

scholarly journals Enterohemorrhagic Escherichia coli Virulence Regulation by Two Bacterial Adrenergic Kinases, QseC and QseE

2011 ◽  
Vol 80 (2) ◽  
pp. 688-703 ◽  
Author(s):  
Jacqueline Njoroge ◽  
Vanessa Sperandio
Keyword(s):  
Escherichia Coli ◽  
Response Regulator ◽  
Enterohemorrhagic Escherichia Coli ◽  
Dependent Manner ◽  
Content Type ◽  
E Coli ◽  
Virulence Regulation ◽  
Sensor Kinases ◽  
Virulence Factor Gene ◽  
Enterocyte Effacement

ABSTRACTThe human pathogen enterohemorrhagicEscherichia coli(EHEC) O157:H7 has two histidine sensor kinases, QseC and QseE, which respond to the mammalian adrenergic hormones epinephrine and norepinephrine by increasing their autophosphorylation. Although QseC and QseE are present in nonpathogenic strains ofE. coli, EHEC exploits these kinases for virulence regulation. To further investigate the full extent of epinephrine and its sensors' impact on EHEC virulence, we performed transcriptomic and phenotypic analyses of single and double deletions ofqseCandqseEgenes in the absence or presence of epinephrine. We showed that in EHEC, epinephrine sensing seems to occur primarily through QseC and QseE. We also observed that QseC and QseE regulate expression of the locus of enterocyte effacement (LEE) genes positively and negatively, respectively. LEE activation, which is required for the formation of the characteristic attaching and effacing (A/E) lesions by EHEC on epithelial cells, is epinephrine dependent. Regulation of the LEE and the non-LEE-contained virulence factor genenleAby QseE is indirect, through transcription inhibition of the RcsB response regulator. Finally, we show that coincubation of HeLa cells with epinephrine increases EHEC infectivity in a QseC- and QseE-dependent manner. These results genetically and phenotypically map the contributions of the two adrenergic sensors QseC and QseE to EHEC pathogenesis.

scholarly journals Conversion of Norepinephrine to 3,4-Dihdroxymandelic Acid in Escherichia coli Requires the QseBC Quorum-Sensing System and the FeaR Transcription Factor

2017 ◽  
Vol 200 (1) ◽  
Author(s):  
Sasikiran Pasupuleti ◽  
Nitesh Sule ◽  
Michael D. Manson ◽  
Arul Jayaraman
Keyword(s):  
Escherichia Coli ◽  
Transcription Factor ◽  
Quorum Sensing ◽  
Aromatic Amines ◽  
Response Regulator ◽  
Content Type ◽  
E Coli ◽  
Expression Of Genes ◽  
K 12 ◽  
Cognate Response Regulator

ABSTRACTThe detection of norepinephrine (NE) as a chemoattractant byEscherichia colistrain K-12 requires the combined action of the TynA monoamine oxidase and the FeaB aromatic aldehyde dehydrogenase. The role of these enzymes is to convert NE into 3,4-dihydroxymandelic acid (DHMA), which is a potent chemoattractant sensed by the Tsr chemoreceptor. These two enzymes must be induced by prior exposure to NE, and cells that are exposed to NE for the first time initially show minimal chemotaxis toward it. The induction of TynA and FeaB requires the QseC quorum-sensing histidine kinase, and the signaling cascade requires new protein synthesis. Here, we demonstrate that the cognate response regulator for QseC, the transcription factor QseB, is also required for induction. The related quorum-sensing kinase QseE appears not to be part of the signaling pathway, but its cognate response regulator, QseF, which is also a substrate for phosphotransfer from QseC, plays a nonessential role. The promoter of thefeaRgene, which encodes a transcription factor that has been shown to be essential for the expression oftynAandfeaB, has two predicted QseB-binding sites. One of these sites appears to be in an appropriate position to stimulate transcription from the P1promoter of thefeaRgene. This study unites two well-known pathways: one for expression of genes regulated by catecholamines (QseBC) and one for expression of genes required for metabolism of aromatic amines (FeaR, TynA, and FeaB). This cross talk allowsE. colito convert the host-derived and chemotactically inert NE into the potent bacterial chemoattractant DHMA.IMPORTANCEThe chemotaxis ofE. coliK-12 to norepinephrine (NE) requires the conversion of NE to 3,4-dihydroxymandleic acid (DHMA), and DHMA is both an attractant and inducer of virulence gene expression for a pathogenic enterohemorrhagicE. coli(EHEC) strain. The induction of virulence by DHMA and NE requires QseC. The results described here show that the cognate response regulator for QseC, QseB, is also required for conversion of NE into DHMA. Production of DHMA requires induction of a pathway involved in the metabolism of aromatic amines. Thus, the QseBC sensory system provides a direct link between virulence and chemotaxis, suggesting that chemotaxis to host signaling molecules may require that those molecules are first metabolized by bacterial enzymes to generate the actual chemoattractant.

scholarly journals Effect of d-Lactate on the Physiological Activity of the ArcB Sensor Kinase in Escherichia coli

2004 ◽  
Vol 186 (7) ◽  
pp. 2085-2090 ◽  
Author(s):  
Claudia Rodriguez ◽  
Ohsuk Kwon ◽  
Dimitris Georgellis
Keyword(s):  
Kinase Activity ◽  
Response Regulator ◽  
Physiological Activity ◽  
Growth Conditions ◽  
Sensor Kinase ◽  
Two Component System ◽  
Direct Signal ◽  
Two Component

ABSTRACT The Arc two-component system, comprising the ArcB sensor kinase and the ArcA response regulator, modulates the expression of numerous genes in response to the respiratory growth conditions. Under anoxic growth conditions ArcB autophosphorylates and transphosphorylates ArcA, which in turn represses or activates its target operons. The anaerobic metabolite d-lactate has been shown to stimulate the in vitro autophosphorylating activity of ArcB. In this study, the in vivo effect of d-lactate on the kinase activity of ArcB was assessed. The results demonstrate that d-lactate does not act as a direct signal for activation of ArcB, as previously proposed, but acts as a physiologically significant effector that amplifies ArcB kinase activity.

scholarly journals Evolved Cobalamin-Independent Methionine Synthase (MetE) Improves the Acetate and Thermal Tolerance of Escherichia coli

2013 ◽  
Vol 79 (24) ◽  
pp. 7905-7915 ◽  
Author(s):  
Elena A. Mordukhova ◽  
Jae-Gu Pan
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Elevated Temperatures ◽  
Defined Medium ◽  
Methionine Synthase ◽  
Mutant Enzyme ◽  
Content Type ◽  
E Coli ◽  
K 12

ABSTRACTAcetate-mediated growth inhibition ofEscherichia colihas been found to be a consequence of the accumulation of homocysteine, the substrate of the cobalamin-independent methionine synthase (MetE) that catalyzes the final step of methionine biosynthesis. To improve the acetate resistance ofE. coli, we randomly mutated the MetE enzyme and isolated a mutant enzyme, designated MetE-214 (V39A, R46C, T106I, and K713E), that conferred accelerated growth in theE. coliK-12 WE strain in the presence of acetate. Additionally, replacement of cysteine 645, which is a unique site of oxidation in the MetE protein, with alanine improved acetate tolerance, and introduction of the C645A mutation into the MetE-214 mutant enzyme resulted in the highest growth rate in acetate-treatedE. colicells among three mutant MetE proteins.E. coliWE strains harboring acetate-tolerant MetE mutants were less inhibited by homocysteine inl-isoleucine-enriched medium. Furthermore, the acetate-tolerant MetE mutants stimulated the growth of the host strain at elevated temperatures (44 and 45°C). Unexpectedly, the mutant MetE enzymes displayed a reduced melting temperature (Tm) but an enhancedin vivostability. Thus, we demonstrate improvedE. coligrowth in the presence of acetate or at elevated temperatures solely due to mutations in the MetE enzyme. Furthermore, when anE. coliWE strain carrying the MetE mutant was combined with a previously found MetA (homoserineo-succinyltransferase) mutant enzyme, the MetA/MetE strain was found to grow at 45°C, a nonpermissive growth temperature forE. coliin defined medium, with a similar growth rate as if it were supplemented byl-methionine.

scholarly journals Role of RcsF in Signaling to the Rcs Phosphorelay Pathway in Escherichia coli

2005 ◽  
Vol 187 (19) ◽  
pp. 6770-6778 ◽  
Author(s):  
Nadim Majdalani ◽  
Michael Heck ◽  
Valerie Stout ◽  
Susan Gottesman
Keyword(s):  
Escherichia Coli ◽  
Cell Surface ◽  
Small Rna ◽  
Kinase Activity ◽  
Response Regulator ◽  
Constitutive Expression ◽  
Activation Mechanism ◽  
Sensor Kinase ◽  
High Level

ABSTRACT The rcs phosphorelay pathway components were originally identified as regulators of capsule synthesis. In addition to the transmembrane sensor kinase RcsC, the RcsA coregulator, and the response regulator RcsB, two new components have been characterized, RcsD and RcsF. RcsD, the product of the yojN gene, now renamed rcsD, acts as a phosphorelay between RcsC and RcsB. Transcription of genes for capsule synthesis (cps) requires both RcsA and RcsB; transcription of other promoters, including that for the small RNA RprA, requires only RcsB. RcsF was described as an alternative sensor kinase for RcsB. We have examined the role of RcsF in the activation of both the rprA and cps promoters. We find that a number of signals that lead to activation of the phosphorelay require both RcsF and RcsC; epistasis experiments place RcsF upstream of RcsC. The RcsF sequence is characteristic of lipoproteins, consistent with a role in sensing cell surface perturbation and transmitting this signal to RcsC. Activation of RcsF does not require increased transcription of the gene, suggesting that modification of the RcsF protein may act as an activating signal. Signals from RcsC require RcsD to activate RcsB. Sequencing of an rcsC allele, rcsC137, that leads to high-level constitutive expression of both cps and rprA suggests that the response regulator domain of RcsC plays a role in negatively regulating the kinase activity of RcsC. The phosphorelay and the variation in the activation mechanism (dependent upon or independent of RcsA) provide multiple steps for modulating the output from this system.

scholarly journals A transcriptome study of the QseEF two-component system and the QseG membrane protein in enterohaemorrhagic Escherichia coli O157 : H7

Microbiology ◽  
2010 ◽  
Vol 156 (4) ◽  
pp. 1167-1175 ◽  
Author(s):  
Nicola C. Reading ◽  
David Rasko ◽  
Alfredo G. Torres ◽  
Vanessa Sperandio
Keyword(s):  
Escherichia Coli ◽  
Membrane Protein ◽  
Response Regulator ◽  
Two Component System ◽  
E Coli ◽  
Enterohaemorrhagic Escherichia Coli ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems ◽  
Type Iii Secretion Effector

QseE is a sensor kinase that responds to epinephrine, sulfate and phosphate. QseE constitutes a two-component signalling system together with the QseF σ 54-dependent response regulator. Encoded within the same operon as qseEF is the qseG gene, which encodes a membrane protein involved in the translocation of a type III secretion effector protein of enterohaemorrhagic Escherichia coli (EHEC) into epithelial cells. The qseEGF genes also form an operon with the glnB gene, which encodes the E. coli nitrogen sensor PII protein. Here we report a transcriptome analysis comparing qseE, qseF andqseG single mutants with the wild-type strain. This study revealed that the proteins encoded by these genes play a modest but significant role in iron uptake. Although QseEFG regulate genes involved in nitrogen utilization, these proteins do not play a notable role in nitrogen metabolism. In addition, QseEFG regulate transcription of the rcsBC and phoPQ two-component systems, linking several signal transduction pathways. The similarity of the microarray profiles of these mutants also indicates that these proteins work together. These data indicate that QseEFG are involved in the regulation of virulence and metabolism in EHEC.

scholarly journals The Escherichia coli BarA-UvrY Two-Component System Is Needed for Efficient Switching between Glycolytic and Gluconeogenic Carbon Sources

2003 ◽  
Vol 185 (3) ◽  
pp. 843-853 ◽  
Author(s):  
Anna-Karin Pernestig ◽  
Dimitris Georgellis ◽  
Tony Romeo ◽  
Kazushi Suzuki ◽  
Henrik Tomenius ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Response Regulator ◽  
Carbon Sources ◽  
Regulation System ◽  
Wild Type ◽  
Two Component System ◽  
Kinase Gene ◽  
Component System ◽  
E Coli ◽  
Two Component

ABSTRACT The Escherichia coli BarA and UvrY proteins were recently demonstrated to constitute a novel two-component system, although its function has remained largely elusive. Here we show that mutations in the sensor kinase gene, barA, or the response regulator gene, uvrY, in uropathogenic E. coli drastically affect survival in long-term competition cultures. Using media with gluconeogenic carbon sources, the mutants have a clear growth advantage when competing with the wild type, but using media with carbon sources feeding into the glycolysis leads to a clear growth advantage for the wild type. Results from competitions with mutants in the carbon storage regulation system, CsrA/B, known to be a master switch between glycolysis and gluconeogenesis, led us to propose that the BarA-UvrY two-component system controls the Csr system. Taking these results together, we propose the BarA-UvrY two-component system is crucial for efficient adaptation between different metabolic pathways, an essential function for adaptation to a new environment.

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