scholarly journals CpxP, a Stress-Combative Member of the Cpx Regulon

1998 ◽  
Vol 180 (4) ◽  
pp. 831-839 ◽  
Author(s):  
Paul N. Danese ◽  
Thomas J. Silhavy
Keyword(s):  
Escherichia Coli ◽  
Envelope Protein ◽  
Periplasmic Protein ◽  
Dependent Manner ◽  
Alkaline Ph ◽  
Signal Transduction System ◽  
Two Component ◽  
Mutant Strains ◽  
Alkaline Conditions ◽  
Two Component Signal Transduction

ABSTRACT The CpxA/R two-component signal transduction system ofEscherichia coli can combat a variety of extracytoplasmic protein-mediated toxicities. The Cpx system performs this function, in part, by increasing the synthesis of the periplasmic protease, DegP. However, other factors are also employed by the Cpx system for this stress-combative function. In an effort to identify these remaining factors, we screened a collection of random lacZ operon fusions for those fusions whose transcription is regulated by CpxA/R. Through this approach, we have identified a new locus,cpxP, whose transcription is stimulated by activation of the Cpx pathway. cpxP specifies a periplasmic protein that can combat the lethal phenotype associated with the synthesis of a toxic envelope protein. In addition, we show that cpxPtranscription is strongly induced by alkaline pH in a CpxA-dependent manner and that cpxP and cpx mutant strains display hypersensitivity to growth in alkaline conditions.

Extracellular Ca2+ transients affect poly-(R)-3-hydroxybutyrate regulation by the AtoS-AtoC system in Escherichia coli

2009 ◽  
Vol 417 (3) ◽  
pp. 667-672 ◽  
Author(s):  
Marina C. Theodorou ◽  
Ekaterini Tiligada ◽  
Dimitrios A. Kyriakidis
Keyword(s):  
Escherichia Coli ◽  
Channel Blocker ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Signal Transduction System ◽  
Two Component System ◽  
Component System ◽  
E Coli ◽  
Two Component ◽  
Membrane Bound

Escherichia coli is exposed to wide extracellular concentrations of Ca2+, whereas the cytosolic levels of the ion are subject to stringent control and are implicated in many physiological functions. The present study shows that extracellular Ca2+ controls cPHB [complexed poly-(R)-3-hydroxybutyrate] biosynthesis through the AtoS-AtoC two-component system. Maximal cPHB accumulation was observed at higher [Ca2+]e (extracellular Ca2+ concentration) in AtoS-AtoC-expressing E. coli compared with their ΔatoSC counterparts, in both cytosolic and membrane fractions. The reversal of EGTA-mediated down-regulation of cPHB biosynthesis by the addition of Ca2+ and Mg2+ was under the control of the AtoS-AtoC system. Moreover, the Ca2+-channel blocker verapamil reduced total and membrane-bound cPHB levels, the inhibitory effect being circumvented by Ca2+ addition only in atoSC+ bacteria. Histamine and compound 48/80 affected cPHB accumulation in a [Ca2+]e-dependent manner directed by the AtoS-AtoC system. In conclusion, these data provide evidence for the involvement of external Ca2+ on cPHB synthesis regulated by the AtoS-AtoC two-component system, thus linking Ca2+ with a signal transduction system, most probably through a transporter.

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 Identification of a Two-Component Signal Transduction System fromCorynebacterium diphtheriae That Activates Gene Expression in Response to the Presence of Heme and Hemoglobin

1999 ◽  
Vol 181 (17) ◽  
pp. 5330-5340 ◽  
Author(s):  
Michael P. Schmitt
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Response Regulator ◽  
Open Reading Frames ◽  
Sensor Kinase ◽  
Dependent Manner ◽  
Signal Transduction System ◽  
Kinase Gene ◽  
Two Component ◽  
Two Component Signal Transduction

ABSTRACT Corynebacterium diphtheriae, the causative agent of diphtheria, utilizes various host compounds to acquire iron. TheC. diphtheriae hmuO gene encodes a heme oxygenase that is involved in the utilization of heme and hemoglobin as iron sources. Transcription of the hmuO gene in C. diphtheriae is controlled under a dual regulatory mechanism in which the diphtheria toxin repressor protein (DtxR) and iron repress expression while either heme or hemoglobin is needed to activate transcription. In this study, two clones isolated from a C. diphtheriae chromosomal library were shown to activate transcription from the hmuO promoter in Escherichia coli. Sequence analysis revealed that these activator clones each carried distinct genes whose products had significant homology to response regulators of two-component signal transduction systems. Located upstream from each of these response regulator homologs are partial open reading frames that are predicted to encode the C-terminal portions of sensor kinases. The full-length sensor kinase gene for each of these systems was cloned from the C. diphtheriaechromosome, and constructs each carrying one complete sensor kinase gene and its cognate response regulator were constructed. One of these constructs, pTSB20, which carried the response regulator (chrA) and its cognate sensor kinase (chrS), was shown to strongly activate transcription from the hmuOpromoter in a heme-dependent manner in E. coli. A mutation in chrA (chrAD50N), which changed a conserved aspartic acid residue at position 50, the presumed site of phosphorylation by ChrS, to an asparagine, abolished heme-dependent activation. These findings suggest that the sensor kinase ChrS is involved in the detection of heme and the transduction of this signal, via a phosphotransfer mechanism, to the response regulator ChrA, which then activates transcription of the hmuO promoter. This is the first report of a bacterial two-component signal transduction system that controls gene expression through a heme-responsive mechanism.

scholarly journals EvgA of the Two-Component Signal Transduction System Modulates Production of the YhiUV Multidrug Transporter in Escherichia coli

2002 ◽  
Vol 184 (8) ◽  
pp. 2319-2323 ◽  
Author(s):  
Kunihiko Nishino ◽  
Akihito Yamaguchi
Keyword(s):  
Escherichia Coli ◽  
Signal Transduction ◽  
Multidrug Resistance ◽  
Multidrug Transporter ◽  
Signal Transduction System ◽  
Two Component ◽  
Two Component Signal Transduction

ABSTRACT Overexpression of the EvgA regulator of the two-component signal transduction system was previously found to modulate multidrug resistance of Escherichia coli by increasing efflux of drugs (K. Nishino and A. Yamaguchi, J. Bacteriol. 183:1455-1458, 2001). Here we present data showing that EvgA contributes to multidrug resistance through increased expression of the multidrug transporter yhiUV gene.

scholarly journals Overexpression of the Response RegulatorevgA of the Two-Component Signal Transduction System Modulates Multidrug Resistance Conferred by Multidrug Resistance Transporters

2001 ◽  
Vol 183 (4) ◽  
pp. 1455-1458 ◽  
Author(s):  
Kunihiko Nishino ◽  
Akihito Yamaguchi
Keyword(s):  
Escherichia Coli ◽  
Multidrug Resistance ◽  
Response Regulator ◽  
Multidrug Efflux ◽  
Signal Transduction System ◽  
Two Component System ◽  
Component System ◽  
Two Component ◽  
Two Component Signal Transduction ◽  
Multidrug Resistance Transporters

ABSTRACT Overexpression of evgA, a response regulator of a two-component system, increased multidrug efflux in Escherichia coli. Since overexpression of the emrKY operon, which is controlled by evgAS, could account only for deoxycholate resistance, the evgAS locus apparently controls expression of at least one other multidrug efflux operon.

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