scholarly journals The CpxRA Signal Transduction System ofEscherichia coli: Growth-Related Autoactivation and Control of Unanticipated Target Operons

1999 ◽  
Vol 181 (21) ◽  
pp. 6772-6778 ◽  
Author(s):  
Peter De Wulf ◽  
Ohsuk Kwon ◽  
E. C. C. Lin
Keyword(s):  
Signal Transduction ◽  
Response Regulator ◽  
Consensus Sequence ◽  
Negative Control ◽  
Northern Hybridization ◽  
Signal Transduction System ◽  
Mobility Shift ◽  
Response Network ◽  
Shift Analysis ◽  
Cognate Response Regulator

ABSTRACT In Escherichia coli, the CpxRA two-component signal transduction system senses and responds to aggregated and misfolded proteins in the bacterial envelope. We show that CpxR-P (the phosphorylated form of the cognate response regulator) activatescpxRA expression in conjunction with RpoS, suggesting an involvement of the Cpx system in stationary-phase survival. Engagement of the CpxRA system in functions beyond protein management is indicated by several putative targets identified after a genomic screening for the CpxR-P recognition consensus sequence. Direct negative control of the newly identified targets motABcheAW (specifying motility and chemotaxis) and tsr (encoding the serine chemoreceptor) by CpxR-P was shown by electrophoretic mobility shift analysis and Northern hybridization. The results suggest that the CpxRA system plays a core role in an extensive stress response network in which the coordination of protein turnover and energy conservation may be the unifying element.

scholarly journals Cpx Two-Component Signal Transduction inEscherichia coli: Excessive CpxR-P Levels Underlie CpxA* Phenotypes

2000 ◽  
Vol 182 (5) ◽  
pp. 1423-1426 ◽  
Author(s):  
Peter De Wulf ◽  
E. C. C. Lin
Keyword(s):  
Signal Transduction ◽  
Response Regulator ◽  
Response Regulators ◽  
Signal Transduction System ◽  
Regulate Gene Expression ◽  
Adverse Conditions ◽  
Two Component ◽  
Sensor Protein ◽  
Two Component Signal Transduction ◽  
Cognate Response Regulator

ABSTRACT In Escherichia coli, the CpxA-CpxR two-component signal transduction system and the ςE and ς32response pathways jointly regulate gene expression in adaptation to adverse conditions. These include envelope protein distress, heat shock, oxidative stress, high pH, and entry into stationary phase. Certain mutant versions of the CpxA sensor protein (CpxA* proteins) exhibit an elevated ratio of kinase to phosphatase activity on CpxR, the cognate response regulator. As a result, CpxA* strains display numerous phenotypes, many of which cannot be easily related to currently known functions of the CpxA-CpxR pathway. It is unclear whether CpxA* phenotypes are caused solely by hyperphosphorylation of CpxR. We here report that all of the tested CpxA* phenotypes depend on elevated levels of CpxR-P and not on cross-signalling of CpxA* to noncognate response regulators.

The tumor suppressor p53 regulates its own transcription

1993 ◽  
Vol 13 (6) ◽  
pp. 3415-3423
Author(s):  
A Deffie ◽  
H Wu ◽  
V Reinke ◽  
G Lozano
Keyword(s):  
Consensus Sequence ◽  
Point Mutations ◽  
Direct Interaction ◽  
Mutant P53 ◽  
Tumor Suppressor P53 ◽  
Mobility Shift ◽  
Shift Analysis ◽  
Promoter Deletion Analysis ◽  
Protein Dna Interactions ◽  
Responsive Element

The ability of p53 to suppress transformation correlates with its ability to activate transcription. To identify targets of p53 transactivation, we examined the p53 promoter itself. Northern (RNA) analysis and transient transfection experiments showed that p53 transcriptionally regulated itself. A functionally inactive mutant p53 could not regulate the p53 promoter. Deletion analysis of the p53 promoter delineated sequences between +22 and +67 as being critical for regulation. Electrophoretic mobility shift analysis and methylation interference pinpointed the p53 DNA responsive element. When oligomerized in front of a heterologous minimal promoter, this element was regulated by wild-type p53 and not by mutant p53. Point mutations in the DNA element that eliminated protein-DNA interactions also resulted in a nonresponsive p53 promoter. The DNA element in the p53 promoter responsive to p53 regulation is similar to the p53 consensus sequence. However, we have been unable to detect a direct interaction of p53 with its promoter.

scholarly journals Multistress Regulation in Escherichia coli: Expression of osmB Involves Two Independent Promoters Responding either to σS or to the RcsCDB His-Asp Phosphorelay

2005 ◽  
Vol 187 (9) ◽  
pp. 3282-3286 ◽  
Author(s):  
Alice Boulanger ◽  
Anne Francez-Charlot ◽  
Annie Conter ◽  
Marie-Pierre Castanié-Cornet ◽  
Kaymeuang Cam ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Signal Transduction ◽  
Transcription Factors ◽  
Response Regulator ◽  
Osmotic Shock ◽  
Dependent Manner ◽  
Signal Transduction System ◽  
Upstream Promoter ◽  
Site Consensus ◽  
Escherichia Coli Expression

ABSTRACT Transcription of the Escherichia coli osmB gene is induced by several stress conditions. osmB is expressed from two promoters, osmBp1 and osmBp2. The downstream promoter, osmBp2, is induced after osmotic shock or upon entry into stationary phase in a σS-dependent manner. The upstream promoter, osmBp1, is independent of σS and is activated by RcsB, the response regulator of the His-Asp phosphorelay signal transduction system RcsCDB. RcsB is responsible for the induction of osmBp1 following treatment with chlorpromazine. Activation of osmBp1 by RcsB requires a sequence upstream of its −35 element similar to the RcsB binding site consensus, suggesting a direct regulatory role. osmB appears as another example of a multistress-responsive gene whose transcription involves both a σS-dependent promoter and a second one independent of σS but controlled by stress-specific transcription factors.

scholarly journals Analysis of a Heme-Dependent Signal Transduction System in Corynebacterium diphtheriae: Deletion of the chrAS Genes Results in Heme Sensitivity and Diminished Heme-Dependent Activation of the hmuO Promoter

2005 ◽  
Vol 73 (11) ◽  
pp. 7406-7412 ◽  
Author(s):  
Lori A. Bibb ◽  
Natalie D. King ◽  
Carey A. Kunkle ◽  
Michael P. Schmitt
Keyword(s):  
Signal Transduction ◽  
Transcriptional Activation ◽  
Transcriptional Activity ◽  
Response Regulator ◽  
Corynebacterium Diphtheriae ◽  
Transcriptional Analysis ◽  
Sensor Kinase ◽  
Signal Transduction System ◽  
Dependent Signal ◽  
Two Component Signal Transduction

ABSTRACT The Corynebacterium diphtheriae hmuO gene encodes a heme oxygenase that is involved in the utilization of heme as an iron source. Transcription of hmuO is activated by heme or hemoglobin and repressed by iron and DtxR. Previous studies with Escherichia coli showed that heme-dependent transcriptional activation of an hmuO promoter-lacZ fusion was dependent on the cloned C. diphtheriae chrA and chrS genes (chrAS), which encode the response regulator and sensor kinase, respectively, of a two-component signal transduction system. In this study, nonpolar deletions in the chrAS genes were constructed on the chromosome of C. diphtheriae. Mutations in chrAS resulted in marked reduction in heme-dependent transcription of hmuO, which indicates that the ChrA/S system is a key regulator at the hmuO promoter. However, low but significant levels of heme-specific transcriptional activity were observed at the hmuO promoter in the chrAS mutants, suggesting that an additional heme-dependent activator is involved in hmuO expression. The chrAS mutants were also sensitive to heme, which was observed only in stationary-phase cultures and correlated with reduced cell viability. The heme sensitivity of the mutants was not due to reduced expression of hmuO, and these results suggest that additional factors controlled by the ChrA/S system may be involved in protection against heme toxicity. Transcriptional analysis of the chrAS operon revealed that it was not autoregulated or affected by iron or heme levels.

Phosphorylation activity of the response regulator of the two-component signal transduction system AtoS–AtoC in E. coli

2005 ◽  
Vol 1725 (3) ◽  
pp. 257-268 ◽  
Author(s):  
Efthimia E. Lioliou ◽  
Eleni P. Mimitou ◽  
Asterios I. Grigoroudis ◽  
Cynthia H. Panagiotidis ◽  
Christos A. Panagiotidis ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Response Regulator ◽  
Signal Transduction System ◽  
E Coli ◽  
Two Component ◽  
Two Component Signal Transduction

scholarly journals CheX in the Three-Phosphatase System of Bacterial Chemotaxis

2007 ◽  
Vol 189 (19) ◽  
pp. 7007-7013 ◽  
Author(s):  
Travis J. Muff ◽  
Richard M. Foster ◽  
Peter J. Y. Liu ◽  
George W. Ordal
Keyword(s):  
Escherichia Coli ◽  
Signal Transduction ◽  
Bacillus Subtilis ◽  
Mutant Strain ◽  
Response Regulator ◽  
Bacterial Chemotaxis ◽  
Signal Transduction System ◽  
Two Component ◽  
Two Component Signal Transduction ◽  
Phosphatase System

ABSTRACT Bacterial chemotaxis involves the regulation of motility by a modified two-component signal transduction system. In Escherichia coli, CheZ is the phosphatase of the response regulator CheY but many other bacteria, including Bacillus subtilis, use members of the CheC-FliY-CheX family for this purpose. While Bacillus subtilis has only CheC and FliY, many systems also have CheX. The effect of this three-phosphatase system on chemotaxis has not been studied previously. CheX was shown to be a stronger CheY-P phosphatase than either CheC or FliY. In Bacillus subtilis, a cheC mutant strain was nearly complemented by heterologous cheX expression. CheX was shown to overcome the ΔcheC adaptational defect but also generally lowered the counterclockwise flagellar rotational bias. The effect on rotational bias suggests that CheX reduced the overall levels of CheY-P in the cell and did not truly replicate the adaptational effects of CheC. Thus, CheX is not functionally redundant to CheC and, as outlined in the discussion, may be more analogous to CheZ.

scholarly journals Rap Phosphatase of Virulence Plasmid pXO1 Inhibits Bacillus anthracis Sporulation

2006 ◽  
Vol 188 (2) ◽  
pp. 487-498 ◽  
Author(s):  
Cristina Bongiorni ◽  
Ricarda Stoessel ◽  
Dorinda Shoemaker ◽  
Marta Perego
Keyword(s):  
Cell Cycle ◽  
Signal Transduction ◽  
Bacillus Anthracis ◽  
Response Regulator ◽  
Selective Advantage ◽  
Virulence Plasmid ◽  
Signal Transduction System ◽  
Developmental Pathway ◽  
Sporulation Initiation ◽  
Carboxy Terminal

ABSTRACT This study shows that the Bacillus anthracis pXO1 virulence plasmid carries a Rap-Phr system, BXA0205, which regulates sporulation initiation in this organism. The BXA0205Rap protein was shown to dephosphorylate the Spo0F response regulator intermediate of the phosphorelay signal transduction system that regulates the initiation of the developmental pathway in response to environmental, metabolic, and cell cycle signals. The activity of the Rap protein was shown to be inhibited by the carboxy-terminal pentapeptide generated through an export-import processing pathway from the associated BXA0205Phr protein. Deregulation of the Rap activity by either overexpression or lack of the Phr pentapeptide resulted in severe inhibition of sporulation. Five additional Rap-Phr encoding systems were identified on the chromosome of B. anthracis, one of which, BA3790-3791, also affected sporulation initiation. The results suggest that the plasmid-borne Rap-Phr system may provide a selective advantage to the virulence of B. anthracis.

scholarly journals Role of the Transporter-Like Sensor Kinase CbrA in Histidine Uptake and Signal Transduction

2015 ◽  
Vol 197 (17) ◽  
pp. 2867-2878 ◽  
Author(s):  
Xue-Xian Zhang ◽  
Jonathan C. Gauntlett ◽  
Darby G. Oldenburg ◽  
Gregory M. Cook ◽  
Paul B. Rainey
Keyword(s):  
Signal Transduction ◽  
Response Regulator ◽  
Nutrient Acquisition ◽  
Coupled Processes ◽  
Sensor Kinase ◽  
Unique Type ◽  
Content Type ◽  
Genes Encoding ◽  
Interdomain Interactions ◽  
Cognate Response Regulator

ABSTRACTCbrA is an atypical sensor kinase found inPseudomonas. The autokinase domain is connected to a putative transporter of the sodium/solute symporter family (SSSF). CbrA functions together with its cognate response regulator, CbrB, and plays an important role in nutrient acquisition, including regulation ofhutgenes for the utilization of histidine and its derivative, urocanate. Here we report on the findings of a genetic and biochemical analysis of CbrA with a focus on the function of the putative transporter domain. The work was initiated with mutagenesis of histidine uptake-proficient strains to identify histidine-specific transport genes located outside thehutoperon. Genes encoding transporters were not identified, but mutations were repeatedly found incbrA. This, coupled with the findings of [3H]histidine transport assays and further mutagenesis, implicated CbrA in histidine uptake. In addition, mutations in different regions of the SSSF domain abolished signal transduction. Site-specific mutations were made at four conserved residues: W55 and G172 (SSSF domain), H766 (H box), and N876 (N box). The mutations W55G, G172H, and N876G compromised histidine transport but had minimal effects on signal transduction. The H766G mutation abolished both transport and signal transduction, but the capacity to transport histidine was restored upon complementation with a transport-defective allele of CbrA, most likely due to interdomain interactions. Our combined data implicate the SSSF domain of CbrA in histidine transport and suggest that transport is coupled to signal transduction.IMPORTANCENutrient acquisition in bacteria typically involves membrane-bound sensors that, via cognate response regulators, determine the activity of specific transporters. However, nutrient perception and uptake are often coupled processes. Thus, from a physiological perspective, it would make sense for systems that couple the process of signaling and transport within a single protein and where transport is itself the stimulus that precipitates signal transduction to have evolved. The CbrA regulator inPseudomonasrepresents a unique type of sensor kinase whose autokinase domain is connected to a transporter domain. We present genetic and biochemical evidence that suggests that CbrA plays a dual role in histidine uptake and sensing and that transport is dependent on signal transduction.

scholarly journals Resistance to Bacitracin in Bacillus subtilis: Unexpected Requirement of the BceAB ABC Transporter in the Control of Expression of Its Own Structural Genes

2007 ◽  
Vol 189 (23) ◽  
pp. 8636-8642 ◽  
Author(s):  
Remi Bernard ◽  
Annick Guiseppi ◽  
Marc Chippaux ◽  
Maryline Foglino ◽  
François Denizot
Keyword(s):  
Signal Transduction ◽  
Bacillus Subtilis ◽  
Abc Transporter ◽  
Defense Mechanism ◽  
Response Regulator ◽  
Nucleotide Binding ◽  
Binding Domain ◽  
Nucleotide Binding Domain ◽  
Signal Transduction System ◽  
Native Form

ABSTRACT The Bacillus subtilis BceAB ABC transporter involved in a defense mechanism against bacitracin is composed of a membrane-spanning domain and a nucleotide-binding domain. Induction of the structural bceAB genes requires the BceR response regulator and the BceS histidine kinase of a signal transduction system. However, despite the presence of such a transduction system and of bacitracin, no transcription from an unaltered bceA promoter is observed in cells lacking the BceAB transporter. Expression in trans of the BceAB transporter in these bceAB cells restores the transcription from the bceA promoter. Cells possessing a mutated nucleotide-binding domain of the transporter are also no longer able to trigger transcription from the bceA promoter in the presence of bacitracin, although the mutated ABC transporter is still bound to the membrane. In these cells, expression of the bceA promoter can no longer be detected, indicating that the ABC transporter not only must be present in the cell membrane, but also must be expressed in a native form for the induction of the bceAB genes. Several hypotheses are discussed to explain the simultaneous need for bacitracin, a native signal transduction system, and an active BceAB ABC transporter to trigger transcription from the bceA promoter.

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