scholarly journals Effects of ISSo2 Insertions in Structural and Regulatory Genes of the Trimethylamine Oxide Reductase of Shewanella oneidensis

2003 ◽  
Vol 185 (6) ◽  
pp. 2042-2045 ◽  
Author(s):  
Christophe Bordi ◽  
Chantal Iobbi-Nivol ◽  
Vincent Méjean ◽  
Jean-Claude Patte
Keyword(s):  
Growth Analysis ◽  
Response Regulator ◽  
Shewanella Oneidensis ◽  
Regulatory Genes ◽  
Trimethylamine Oxide ◽  
Tmao Reductase

ABSTRACT We have isolated three Shewanella oneidensis mutants specifically impaired in trimethylamine oxide (TMAO) respiration. The mutations arose from insertions of an ISSo2 element into torA, torR, and torS, encoding, respectively, the TMAO reductase TorA, the response regulator TorR, and the sensor TorS. Although TorA is not the sole enzyme reducing TMAO in S. oneidensis, growth analysis showed that it is the main respiratory TMAO reductase. Use of a plasmid-borne torE′-lacZ fusion confirmed that the TorS-TorR phosphorelay mediates TMAO induction of the torECAD operon.

scholarly journals Genes Regulated by TorR, the Trimethylamine Oxide Response Regulator of Shewanella oneidensis

2004 ◽  
Vol 186 (14) ◽  
pp. 4502-4509 ◽  
Author(s):  
Christophe Bordi ◽  
Mireille Ansaldi ◽  
Stéphanie Gon ◽  
Cécile Jourlin-Castelli ◽  
Chantal Iobbi-Nivol ◽  
...  
Keyword(s):  
Response Regulator ◽  
Shewanella Oneidensis ◽  
Direct Repeat ◽  
Start Site ◽  
Site Location ◽  
Promoter Regions ◽  
Trimethylamine Oxide ◽  
Single Operator ◽  
Operator Site

ABSTRACT The torECAD operon encoding the trimethylamine oxide (TMAO) respiratory system of Shewanella oneidensis is positively controlled by the TorS/TorR two-component system when TMAO is available. Activation of the tor operon occurs upon binding of the phosphorylated response regulator TorR to a single operator site containing the direct repeat nucleotide sequence TTCATAN4TTCATA. Here we show that the replacement of any nucleotide of one TTCATA hexamer prevented TorR binding in vitro, meaning that TorR specifically interacts with this DNA target. Identical direct repeat sequences were found in the promoter regions of torR and of the new gene torF (SO4694), and they allowed TorR binding to both promoters. Real-time PCR experiments revealed that torR is negatively autoregulated, whereas torF is strongly induced by TorR in response to TMAO. Transcription start site location and footprinting analysis indicate that the operator site at torR overlaps the promoter −10 box, whereas the operator site at torF is centered at −74 bp from the start site, in agreement with the opposite role of TorR in the regulation of the two genes. Since torF and torECAD are positively coregulated by TorR, we propose that the TorF protein plays a role related to TMAO respiration.

scholarly journals Reconstitution of the Trimethylamine Oxide Reductase Regulatory Elements of Shewanella oneidensis in Escherichia coli

2002 ◽  
Vol 184 (5) ◽  
pp. 1262-1269 ◽  
Author(s):  
Stéphanie Gon ◽  
Jean-Claude Patte ◽  
Jean-Philippe Dos Santos ◽  
Vincent Méjean
Keyword(s):  
Escherichia Coli ◽  
Gene Cluster ◽  
Response Regulator ◽  
Regulatory Gene ◽  
Regulatory System ◽  
Regulatory Elements ◽  
Oxygen Control ◽  
E Coli ◽  
Trimethylamine Oxide ◽  
Tmao Reductase

ABSTRACT Several bacteria can grow by using small organic compounds such as trimethylamine oxide (TMAO) as electron acceptors. In Shewanella species, the TMAO reductase respiratory system is encoded by the torECAD operon. We showed that production of the TMAO reductase of S. oneidensis was induced by TMAO and repressed by oxygen, and we noticed that a three-gene cluster (torSTR) encoding a complex two-component regulatory system was present downstream of the torECAD operon. We introduced the torSTR gene cluster into Escherichia coli and showed that this regulatory gene cluster is involved in TMAO induction of the torE promoter but plays no role in the oxygen control. The TorR response regulator was purified, and gel shift and footprinting experiments revealed that TorR binds to a single region located about 70 bases upstream of the transcription start site of the tor structural operon. By deletion analysis, we confirmed that the TorR operator site is required for induction of the tor structural promoter. As the TMAO regulatory system of S. oneidensis is homologous to that of E. coli, we investigated a possible complementation between the TMAO regulatory components of the two bacteria. Interestingly, TorSec, the TMAO sensor of E. coli, was able to transphosphorylate TorRso, the TMAO response regulator of S. oneidensis.

scholarly journals Mutations in Four Regulatory Genes Have Interrelated Effects on Heterocyst Maturation in Anabaena sp. Strain PCC 7120

2006 ◽  
Vol 188 (21) ◽  
pp. 7387-7395 ◽  
Author(s):  
Sigal Lechno-Yossef ◽  
Qing Fan ◽  
Shigeki Ehira ◽  
Naoki Sato ◽  
C. Peter Wolk
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Response Regulator ◽  
Regulatory System ◽  
Transcript Abundance ◽  
Regulatory Genes ◽  
Wild Type ◽  
Serine Threonine Kinase ◽  
In The Wild ◽  
Pcc 7120

ABSTRACT Regulatory genes hepK, hepN, henR, and hepS are required for heterocyst maturation in Anabaena sp. strain PCC 7120. They presumptively encode two histidine kinases, a response regulator, and a serine/threonine kinase, respectively. To identify relationships between those genes, we compared global patterns of gene expression, at 14 h after nitrogen step-down, in corresponding mutants and in the wild-type strain. Heterocyst envelopes of mutants affected in any of those genes lack a homogeneous, polysaccharide layer. Those of a henR mutant also lack a glycolipid layer. patA, which encodes a positive effector of heterocyst differentiation, was up-regulated in all mutants except the hepK mutant, suggesting that patA expression may be inhibited by products related to heterocyst development. hepS and hepK were up-regulated if mutated and so appear to be negatively autoregulated. HepS and HenR regulated a common set of genes and so appear to belong to one regulatory system. Some nontranscriptional mechanism may account for the observation that henR mutants lack, and hepS mutants possess, a glycolipid layer, even though both mutations down-regulated genes involved in formation of the glycolipid layer. HepK and HepN also affected transcription of a common set of genes and therefore appear to share a regulatory pathway. However, the transcript abundance of other genes differed very significantly from expression in the wild-type strain in either the hepK or hepN mutant while differing very little from wild-type expression in the other of those two mutants. Therefore, hepK and hepN appear to participate also in separate pathways.

scholarly journals Molecular Mechanisms of Phosphate Stress Activation of Pseudomonas aeruginosa Quorum Sensing Systems

mSphere ◽  
2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Xianfa Meng ◽  
Stephen Dela Ahator ◽  
Lian-Hui Zhang
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Response Regulator ◽  
Regulatory System ◽  
Regulatory Genes ◽  
Phosphate Deficiency ◽  
Content Type ◽  
Sensing Systems ◽  
Two Component ◽  
Phosphate Depletion

ABSTRACT The hierarchical quorum sensing (QS) systems of Pseudomonas aeruginosa, consisting of las, pqs, and rhl, coordinate the expression of bacterial virulence genes. Previous studies showed that under phosphate deficiency conditions, two-component regulatory system PhoRB could activate various genes involved in cytotoxicity through modulation of QS systems, but the mechanism by which PhoR/PhoB influences QS remains largely unknown. Here, we provide evidence that among the key QS regulatory genes in P. aeruginosa, rhlR, pqsA, mvfR, and lasI were activated by the response regulator PhoB under phosphate-depleted conditions. We show that PhoB is a strong competitor against LasR and RsaL for binding to the promoter of lasI and induces significant expression of lasI, rhlR, and mvfR. However, expression of lasI, encoding the signal 3-oxo-C12-HSL, was increased only marginally under the same phosphate-depleted conditions. This seeming inconsistency was attributed to the induction of pvdQ, which encodes an enzyme for degradation of 3-oxo-C12-HSL signal molecules. Taken together, the results from this study demonstrate that through the two-component regulatory system PhoR/PhoB, phosphate depletion stress could influence the QS network by modulating several key regulators, including lasI, rhlR, mvfR, and pvdQ. The findings highlight not only the potency of the PhoR/PhoB-mediated bacterial stress response mechanism but also the plasticity of the P. aeruginosa QS systems in coping with the changed environmental conditions. IMPORTANCE It is not fully understood how phosphate deficiency could influence the virulence of Pseudomonas aeruginosa through modulation of the bacterial QS systems. This report presents a systemic investigation on the impact of phosphate depletion on the hierarchy of quorum sensing systems of P. aeruginosa. The results showed that phosphate stress could have an extensive impact on the QS networks of this bacterial pathogen. Among the 7 QS regulatory genes representing the 3 sets of QS systems tested, 4 were significantly upregulated by phosphate depletion stress through the PhoR/PhoB two-component regulatory system, especially the upstream QS regulatory gene lasI. We also present evidence that the response regulator PhoB was a strong competitor against the las regulators LasR and RsaL for the lasI promoter, unveiling the mechanistic basis of the process by which phosphate stress could modulate the bacterial QS systems.

scholarly journals Shewanella oneidensis arcA Mutation Impairs Aerobic Growth Mainly by Compromising Translation

Life ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 926
Author(s):  
Peilu Xie ◽  
Jiahao Wang ◽  
Huihui Liang ◽  
Haichun Gao
Keyword(s):  
Response Regulator ◽  
Shewanella Oneidensis ◽  
Growth Defect ◽  
Primary System ◽  
Translation Efficiency ◽  
Aerobic Growth ◽  
Regulatory Systems ◽  
Metabolic Transition ◽  
Ribosome Biosynthesis ◽  
Major Defect

Arc (anoxic redox control), one of the most intensely investigated two-component regulatory systems in γ-proteobacteria, plays a major role in mediating the metabolic transition from aerobiosis to anaerobiosis. In Shewanella oneidensis, a research model for respiratory versatility, Arc is crucial for aerobic growth. However, how this occurs remains largely unknown. In this study, we demonstrated that the loss of the response regulator ArcA distorts the correlation between transcription and translation by inhibiting the ribosome biosynthesis. This effect largely underlies the growth defect because it concurs with the effect of chloramphenicol, which impairs translation. Reduced transcription of ArcA-dependent ribosomal protein S1 appears to have a significant impact on ribosome assembly. We further show that the lowered translation efficiency is not accountable for the envelope defect, another major defect resulting from the ArcA loss. Overall, our results suggest that although the arcA mutation impairs growth through multi-fold complex impacts in physiology, the reduced translation efficacy appears to be a major cause for the phenotype, demonstrating that Arc is a primary system that coordinates proteomic resources with metabolism in S. oneidensis.

scholarly journals A complex regulatory network controls aerobic ethanol oxidation in Pseudomonas aeruginosa: indication of four levels of sensor kinases and response regulators

Microbiology ◽  
2010 ◽  
Vol 156 (5) ◽  
pp. 1505-1516 ◽  
Author(s):  
Demissew S. Mern ◽  
Seung-Wook Ha ◽  
Viola Khodaverdi ◽  
Nicole Gliese ◽  
Helmut Görisch
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Regulatory Network ◽  
Ethanol Oxidation ◽  
Paracoccus Denitrificans ◽  
Response Regulator ◽  
Regulatory Genes ◽  
Response Regulators ◽  
Two Component ◽  
Sensor Kinases ◽  
Complex Regulatory Network

In addition to the known response regulator ErbR (former AgmR) and the two-component regulatory system EraSR (former ExaDE), three additional regulatory proteins have been identified as being involved in controlling transcription of the aerobic ethanol oxidation system in Pseudomonas aeruginosa. Two putative sensor kinases, ErcS and ErcS′, and a response regulator, ErdR, were found, all of which show significant similarity to the two-component flhSR system that controls methanol and formaldehyde metabolism in Paracoccus denitrificans. All three identified response regulators, EraR (formerly ExaE), ErbR (formerly AgmR) and ErdR, are members of the luxR family. The three sensor kinases EraS (formerly ExaD), ErcS and ErcS′ do not contain a membrane domain. Apparently, they are localized in the cytoplasm and recognize cytoplasmic signals. Inactivation of gene ercS caused an extended lag phase on ethanol. Inactivation of both genes, ercS and ercS′, resulted in no growth at all on ethanol, as did inactivation of erdR. Of the three sensor kinases and three response regulators identified thus far, only the EraSR (formerly ExaDE) system forms a corresponding kinase/regulator pair. Using reporter gene constructs of all identified regulatory genes in different mutants allowed the hierarchy of a hypothetical complex regulatory network to be established. Probably, two additional sensor kinases and two additional response regulators, which are hidden among the numerous regulatory genes annotated in the genome of P. aeruginosa, remain to be identified.

scholarly journals Transcriptional regulator ArcA mediates expression of oligopeptide transport systems both directly and indirectly in Shewanella oneidensis

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Huihui Liang ◽  
Yinting Mao ◽  
Yijuan Sun ◽  
Haichun Gao
Keyword(s):  
Response Regulator ◽  
Shewanella Oneidensis ◽  
Anaerobic Growth ◽  
Transport Systems ◽  
Peptide Transporter ◽  
Growth Defect ◽  
Aerobic Growth ◽  
Two Component System ◽  
Metabolic Transition ◽  
Peptide Uptake

Abstract In γ-proteobacterial species, such as Escherichia coli, the Arc (anoxic redox control) two-component system plays a major role in mediating the metabolic transition from aerobiosis to anaerobiosis, and thus is crucial for anaerobic growth but dispensable for aerobic growth. In Shewanella oneidensis, a bacterium renowned for respiratory versatility, Arc (SoArc) primarily affects aerobic growth. To date, how this occurs has remained largely unknown although the growth defect resulting from the loss of DNA-binding response regulator SoArcA is tryptone-dependent. In this study, we demonstrated that the growth defect is in part linked to utilization of oligopeptides and di-tripeptides, and peptide uptake but not peptide degradation is significantly affected by the SoArcA loss. A systematic characterization of major small peptide uptake systems manifests that ABC peptide transporter Sap and four proton-dependent oligopeptide transporters (POTs) are responsible for transport of oligopeptides and di-tripeptides respectively. Among them, Sap and DtpA (one of POTs) are responsive to the SoarcA mutation but only dtpA is under the direct control of SoArcA. We further showed that both Sap and DtpA, when overproduced, improve growth of the SoarcA mutant. While the data firmly establish a link between transport of oligopeptides and di-tripeptides and the SoarcA mutation, other yet-unidentified factors are implicated in the growth defect resulting from the SoArcA loss.

scholarly journals ArcS, the Cognate Sensor Kinase in an Atypical Arc System of Shewanella oneidensis MR-1

2010 ◽  
Vol 76 (10) ◽  
pp. 3263-3274 ◽  
Author(s):  
Jürgen Lassak ◽  
Anna-Lena Henche ◽  
Lucas Binnenkade ◽  
Kai M. Thormann
Keyword(s):  
Escherichia Coli ◽  
Response Regulator ◽  
Phylogenetic Analyses ◽  
Shewanella Oneidensis ◽  
Sensor Kinase ◽  
Two Component System ◽  
Oxygen Levels ◽  
Protein Protein Interaction ◽  
Sequence Homologies ◽  
Cognate Response Regulator

ABSTRACT The availability of oxygen is a major environmental factor for many microbes, in particular for bacteria such as Shewanella species, which thrive in redox-stratified environments. One of the best-studied systems involved in mediating the response to changes in environmental oxygen levels is the Arc two-component system of Escherichia coli, consisting of the sensor kinase ArcB and the cognate response regulator ArcA. An ArcA ortholog was previously identified in Shewanella, and as in Escherichia coli, Shewanella ArcA is involved in regulating the response to shifts in oxygen levels. Here, we identified the hybrid sensor kinase SO_0577, now designated ArcS, as the previously elusive cognate sensor kinase of the Arc system in Shewanella oneidensis MR-1. Phenotypic mutant characterization, transcriptomic analysis, protein-protein interaction, and phosphotransfer studies revealed that the Shewanella Arc system consists of the sensor kinase ArcS, the single phosphotransfer domain protein HptA, and the response regulator ArcA. Phylogenetic analyses suggest that HptA might be a relict of ArcB. Conversely, ArcS is substantially different with respect to overall sequence homologies and domain organizations. Thus, we speculate that ArcS might have adopted the role of ArcB after a loss of the original sensor kinase, perhaps as a consequence of regulatory adaptation to a redox-stratified environment.

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