Competence Modulation by the NADH Oxidase ofStreptococcus pneumoniae Involves Signal Transduction

ABSTRACT Oxygen controls competence development in Streptococcus pneumoniae. Oxygen signaling involves the two-component signal transduction systems CiaRH and ComDE and the competence-stimulating peptide encoded by comC and processed by ComAB. We found that NADH oxidase (Nox) was required for optimal competence. Transcriptional analysis and genetic dissection showed that Nox was involved in post-transcriptional activation of the response regulator ComE and in the transcriptional control of ciaRH andcomCDE. Thus, in S. pneumoniae, Nox, with O2 as its secondary substrate, is part of the O2-signaling pathway.

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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

Infection and Immunity ◽

10.1128/iai.73.11.7406-7412.2005 ◽

2005 ◽

Vol 73 (11) ◽

pp. 7406-7412 ◽

Cited By ~ 28

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.

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A Selective Tether Recruits Activated Response Regulator CheB to Its Chemoreceptor Substrate

mBio ◽

10.1128/mbio.03106-21 ◽

2021 ◽

Author(s):

Mingshan Li ◽

Xianjin Xu ◽

Xiaoqin Zou ◽

Gerald L. Hazelbauer

Keyword(s):

Signal Transduction ◽

Response Regulator ◽

Response Regulators ◽

Two Component ◽

Primary Means ◽

Two Component Signal Transduction ◽

Sense And Respond ◽

Signal Transduction Systems

Two-component signal transduction systems are a primary means by which bacteria sense and respond to their environment. Response regulators are key components of these systems.

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Comparative analysis of two-component signal transduction systems of Bacillus cereus, Bacillus thuringiensis and Bacillus anthracis

Microbiology ◽

10.1099/mic.0.29137-0 ◽

2006 ◽

Vol 152 (10) ◽

pp. 3035-3048 ◽

Cited By ~ 37

Author(s):

Mark de Been ◽

Christof Francke ◽

Roy Moezelaar ◽

Tjakko Abee ◽

Roland J. Siezen

Keyword(s):

Signal Transduction ◽

Bacillus Cereus ◽

Response Regulator ◽

Adaptive Responses ◽

Wide Range ◽

Two Component ◽

Two Component Signal Transduction ◽

Host Microbe Interactions ◽

Cognate Response Regulator ◽

Signal Transduction Systems

Members of the Bacillus cereus group are ubiquitously present in the environment and can adapt to a wide range of environmental fluctuations. In bacteria, these adaptive responses are generally mediated by two-component signal transduction systems (TCSs), which consist of a histidine kinase (HK) and its cognate response regulator (RR). With the use of in silico techniques, a complete set of HKs and RRs was recovered from eight completely sequenced B. cereus group genomes. By applying a bidirectional best-hits method combined with gene neighbourhood analysis, a footprint of these proteins was made. Around 40 HK-RR gene pairs were detected in each member of the B. cereus group. In addition, each member contained many HK and RR genes not encoded in pairs (‘orphans’). Classification of HKs and RRs based on their enzymic domains together with the analysis of two neighbour-joining trees of these domains revealed putative interaction partners for most of the ‘orphans’. Putative biological functions, including involvement in virulence and host–microbe interactions, were predicted for the B. cereus group HKs and RRs by comparing them with those of B. subtilis and other micro-organisms. Remarkably, B. anthracis appeared to lack specific HKs and RRs and was found to contain many truncated, putatively non-functional, HK and RR genes. It is hypothesized that specialization of B. anthracis as a pathogen could have reduced the range of environmental stimuli to which it is exposed. This may have rendered some of its TCSs obsolete, ultimately resulting in the deletion of some HK and RR genes.

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Comprehensive Studies of Drug Resistance Mediated by Overexpression of Response Regulators of Two-Component Signal Transduction Systems in Escherichia coli

Journal of Bacteriology ◽

10.1128/jb.185.6.1851-1856.2003 ◽

2003 ◽

Vol 185 (6) ◽

pp. 1851-1856 ◽

Cited By ~ 102

Author(s):

Hidetada Hirakawa ◽

Kunihiko Nishino ◽

Takahiro Hirata ◽

Akihito Yamaguchi

Keyword(s):

Escherichia Coli ◽

Signal Transduction ◽

Drug Resistance ◽

Response Regulator ◽

Gene Knockout ◽

Open Reading Frames ◽

Two Component ◽

Two Component Signal Transduction ◽

Regulator Genes ◽

Signal Transduction Systems

ABSTRACT In Escherichia coli, there are 32 open reading frames (ORFs) that are assumed to be response regulator genes of two-component signal transduction systems on the basis of sequence similarities. We cloned all of these 32 ORFs into a multicopy expression vector and investigated whether or not they confer drug resistance via control of drug resistance determinants. Fifteen of these ORFs, i.e., baeR, citB, cpxR, evgA, fimZ, kdpE, narL, narP, ompR, rcsB, rstA, torR, yedW, yehT, and dcuR, conferred increased single- or multidrug resistance. Two-thirds of them conferred deoxycholate resistance. Five of them, i.e., evgA, baeR, ompR, cpxR, and rcsB, modulated the expression of several drug exporter genes. The drug resistance mediated by evgA, baeR, and cpxR could be assigned to drug exporters by using drug exporter gene knockout strains.

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An Essential Two-Component Signal Transduction System in Mycobacterium tuberculosis

Journal of Bacteriology ◽

10.1128/jb.182.13.3832-3838.2000 ◽

2000 ◽

Vol 182 (13) ◽

pp. 3832-3838 ◽

Cited By ~ 140

Author(s):

Thomas C. Zahrt ◽

Vojo Deretic

Keyword(s):

Signal Transduction ◽

Mycobacterium Tuberculosis ◽

Transcriptional Activation ◽

Response Regulator ◽

Mrna Levels ◽

Phagocytic Cells ◽

S1 Nuclease ◽

Two Component ◽

Two Component Signal Transduction

ABSTRACT The bacterial two-component signal transduction systems regulate adaptation processes and are likely to play a role inMycobacterium tuberculosis physiology and pathogenesis. The previous initial characterization of an M. tuberculosis response regulator from one of these systems,mtrA-mtrB, suggested its transcriptional activation during infection of phagocytic cells. In this work, we further characterized the mtrA response regulator fromM. tuberculosis H37Rv. Inactivation ofmtrA on the chromosome of M. tuberculosisH37Rv was possible only in the presence of plasmid-borne functionalmtrA, suggesting that this response regulator is essential for M. tuberculosis viability. In keeping with these findings, expression of mtrA in M. tuberculosis H37Rv was detectable during in vitro growth, as determined by S1 nuclease protection and primer extension analyses of mRNA levels and mapping of transcript 5′ ends. The mtrAgene was expressed differently in virulent M. tuberculosis and the vaccine strain M. tuberculosis var. bovis BCG during infection of macrophages, as determined by monitoring of mtrA-gfp fusion activity. In M. bovis BCG, mtrA was induced upon entry into macrophages. In M. tuberculosis H37Rv, its expression was constitutive and unchanged upon infection of murine or human monocyte-derived macrophages. In conclusion, these results identify mtrA as an essential response regulator gene in M. tuberculosis which is differentially expressed in virulent and avirulent strains during growth in macrophages.

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