scholarly journals Genomic and Transcriptomic Analysis of Colistin-Susceptible and Colistin-Resistant Isolates Identify Two-Component System EvgS/EvgA Associated with Colistin Resistance in Escherichia coli

2021 ◽  
Vol Volume 14 ◽  
pp. 2437-2447
Author(s):  
Fen Wan ◽  
Linna Xu ◽  
Zhi Ruan ◽  
Qixia Luo
Keyword(s):  
Escherichia Coli ◽  
Transcriptomic Analysis ◽  
Colistin Resistance ◽  
Two Component System ◽  
Component System ◽  
Two Component

HprSR is a Reactive Chlorine Species-Sensing, Two-Component System in Escherichia coli

2021 ◽  
Author(s):  
Sara El Hajj ◽  
Camille Henry ◽  
Camille Andrieu ◽  
Alexandra Vergnes ◽  
Laurent Loiseau ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hypochlorous Acid ◽  
Methionine Sulfoxide ◽  
Methionine Sulfoxide Reductase ◽  
Repair System ◽  
Bacterial Cells ◽  
Two Component System ◽  
Component System ◽  
Two Component ◽  
Redox Switch

Two-component systems (TCS) are signalling pathways that allow bacterial cells to sense, respond and adapt to fluctuating environments. Among the classical TCS of Escherichia coli , HprSR has recently been shown to be involved in the regulation of msrPQ , which encodes the periplasmic methionine sulfoxide reductase system. In this study, we demonstrate that hypochlorous acid (HOCl) induces the expression of msrPQ in an HprSR-dependant manner, whereas H 2 O 2 , NO and paraquat (a superoxide generator) do not. Therefore, HprS appears to be an HOCl-sensing histidine kinase. Using a directed mutagenesis approach, we show that Met residues located in the periplasmic loop of HprS are important for its activity: as HOCl preferentially oxidizes Met residues, we provide evidence that HprS could be activated via the reversible oxidation of its methionine residues, meaning that MsrPQ plays a role in switching HprSR off. We propose that the activation of HprS by HOCl could occur through a Met redox switch. HprSR appears to be the first characterized TCS able to detect reactive chlorine species (RCS) in E. coli . This study represents an important step towards understanding the mechanisms of RCS resistance in prokaryotes. IMPORTANCE Understanding how bacteria respond to oxidative stress at the molecular level is crucial in the fight against pathogens. HOCl is one of the most potent industrial and physiological microbiocidal oxidants. Therefore bacteria have developed counterstrategies to survive HOCl-induced stress. Over the last decade, important insights into these bacterial protection factors have been obtained. Our work establishes HprSR as a reactive chlorine species-sensing, two-component system in Escherichia coli MG1655, which regulates the expression of MsrPQ, a repair system for HOCl-oxidized proteins. Moreover we provide evidence suggesting that HOCl could activate HprS through a methionine redox switch.

Involvement of AtoSC two-component system in Escherichia coli flagellar regulon

Amino Acids ◽  
2011 ◽  
Vol 43 (2) ◽  
pp. 833-844 ◽  
Author(s):  
Marina C. Theodorou ◽  
Evaggelos C. Theodorou ◽  
Dimitrios A. Kyriakidis
Keyword(s):  
Escherichia Coli ◽  
Two Component System ◽  
Component System ◽  
Two Component ◽  
Flagellar Regulon

scholarly journals Polar Localization of a Tripartite Complex of the Two-Component System DcuS/DcuR and the Transporter DctA in Escherichia coli Depends on the Sensor Kinase DcuS

PLoS ONE ◽  
2014 ◽  
Vol 9 (12) ◽  
pp. e115534 ◽  
Author(s):  
Patrick D. Scheu ◽  
Philipp A. Steinmetz ◽  
Felix Dempwolff ◽  
Peter L. Graumann ◽  
Gottfried Unden
Keyword(s):  
Escherichia Coli ◽  
Sensor Kinase ◽  
Two Component System ◽  
Component System ◽  
Polar Localization ◽  
Two Component

scholarly journals First Insights into the Unexplored Two-Component System YehU/YehT in Escherichia coli

2012 ◽  
Vol 194 (16) ◽  
pp. 4272-4284 ◽  
Author(s):  
T. Kraxenberger ◽  
L. Fried ◽  
S. Behr ◽  
K. Jung
Keyword(s):  
Escherichia Coli ◽  
Two Component System ◽  
Component System ◽  
Two Component

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.

Modulation of virulence genes by the two-component system PhoP-PhoQ in avian pathogenic Escherichia coli

2016 ◽  
Vol 19 (1) ◽  
pp. 31-40 ◽  
Author(s):  
Jian Tu ◽  
Boyan Huang ◽  
Yu Zhang ◽  
Yuxi Zhang ◽  
Ting Xue ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Mutant Strain ◽  
Virulence Genes ◽  
Avian Pathogenic Escherichia Coli ◽  
Two Component System ◽  
Component System ◽  
Transcript Levels ◽  
Pathogenic Escherichia Coli ◽  
Two Component ◽  
Viable Bacteria

Abstract Avian pathogenic Escherichia coli (APEC) infections are a very important problem in the poultry industry. PhoP-PhoQ is a two-component system that regulates virulence genes in APEC. In this study, we constructed strains that lacked the PhoP or PhoQ genes to assess regulation of APEC pathogenicity by the PhoP-PhoQ two-component system. The PhoP mutant strain AE18, PhoQ mutant strain AE19, and PhoP/PhoQ mutant strain AE20 were constructed by the Red homologous recombination method. Swim plates were used to evaluate the motility of the APEC strains, viable bacteria counting was used to assess adhesion and invasion of chick embryo fibroblasts, and Real-Time PCR was used to measure mRNA expression of virulence genes. We first confirmed that AE18, AE19, and AE20 were successfully constructed from the wild-type AE17 strain. AE18, AE19, and AE20 showed significant decreases in motility of 70.97%, 83.87%, and 37.1%, respectively, in comparison with AE17. Moreover, in comparison with AE17, AE18, AE19, and AE20 showed significant decreases of 63.11%, 65.42%, and 30.26%, respectively, in CEF cell adhesion, and significant decreases of 59.83%, 57.82%, and 37.90%, respectively, in CEF cell invasion. In comparison with AE17, transcript levels of sodA, polA, and iss were significantly decreased in AE18, while transcript levels of fimC and iss were significantly decreased in AE19. Our results demonstrate that deletion of PhoP or PhoQ inhibits invasion and adhesion of APEC to CEF cells and significantly reduces APEC virulence by regulating transcription of virulence genes.

scholarly journals MgrB dependent colistin resistance in Klebsiella pneumoniae is associated with an increase in host-to-host transmission

2021 ◽  
Author(s):  
Andrew S. Bray ◽  
Richard D. Smith ◽  
Andrew W. Hudson ◽  
Giovanna E. Hernandez ◽  
Taylor M. Young ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Murine Model ◽  
Regulatory Protein ◽  
Common Mutation ◽  
Colistin Resistance ◽  
Two Component System ◽  
Component System ◽  
Gut Colonization ◽  
Two Component ◽  
Biological Cost

AbstractDue to its high transmissibility, Klebsiella pneumoniae (Kpn) is one of the leading causes of nosocomial infections. Here, we studied the biological cost of colistin resistance, an antibiotic of last resort, of this opportunistic pathogen using a murine model of gut colonization and transmission. Colistin resistance in Kpn is commonly the result of inactivation of the small regulatory protein MgrB. Without a functional MgrB, the two-component system PhoPQ is constitutively active, leading to increased lipid A modifications and subsequent colistin resistance. Using an engineered MgrB mutant, we observed that MgrB-dependent colistin resistance is not associated with a fitness defect during in vitro growth conditions. However, colistin-resistant Kpn colonizes the murine gut poorly, which may be due to the decreased production of capsular polysaccharide by the mutant. The colistin-resistant mutant of Kpn had increased survival outside the host when compared to the parental colistin-sensitive strain. We attribute this enhanced survivability to dysregulation of the PhoPQ two-component system and accumulation of the master stress regulator RpoS. The enhanced survival of the colistin resistant strain may be a key factor in the observed rapid host-to-host transmission in our model. Together, our data demonstrate that colistin-resistant Kpn experiences a biological cost in gastrointestinal colonization. However, this cost is mitigated by enhanced survival outside the host, increasing the risk of transmission. Additionally, it underscores the importance of considering the entire life cycle of a pathogen to truly determine the biological cost associated with antibiotic resistance.ImportanceThe biological cost associated with colistin resistance in Klebsiella pneumoniae (Kpn) was examined using a murine model of Kpn gut colonization and fecal-oral transmission. A common mutation resulting in colistin resistance in Kpn is a loss-of-function mutation of the small regulatory protein MgrB that regulates the two-component system PhoPQ. Even though colistin resistance in Kpn comes with a fitness defect in gut colonization, it increases bacterial survival outside the host enabling it to more effectively transmit to a new host. The enhanced survival is dependent upon the accumulation of RpoS and dysregulation of the PhoPQ. Hence, our study expands our understanding of the underlying molecular mechanism contributing to the transmission of colistin-resistant Kpn.

scholarly journals Roles of the EnvZ/OmpR Two-Component System and Porins in Iron Acquisition in Escherichia coli

2020 ◽  
Author(s):  
Henri Gerken ◽  
Phu Vuong ◽  
Ketaki Soparkar ◽  
Rajeev Misra
Keyword(s):  
Escherichia Coli ◽  
Iron Homeostasis ◽  
Anaerobic Growth ◽  
Transport Systems ◽  
Uptake System ◽  
Two Component System ◽  
Transport Pathway ◽  
Component System ◽  
Two Component ◽  
Positive Effect

ABSTRACTEscherichia coli secretes high-affinity Fe3+ chelators to solubilize and transport chelated Fe3+ via specific outer membrane receptors. In microaerobic and anaerobic growth environments, where the reduced Fe2+ form is predominant, ferrous transport systems fulfill the bacterial need for iron. Expression of genes coding for iron metabolism is controlled by Fur, which when bound to Fe2+ acts as a repressor. Work carried out in this paper shows that the constitutively activated EnvZ/OmpR two-component system, which normally controls expression of the ompC and ompF porin genes, dramatically increases the intracellular pool of accessible iron, as determined by whole-cell electron paramagnetic resonance (EPR) spectroscopy, by inducing the OmpC/FeoB-mediated ferrous transport pathway. Elevated levels of intracellular iron in turn activated Fur, which inhibited the ferric but not the ferrous transport pathway. The data show that the positive effect of constitutively activated EnvZ/OmpR on feoB expression is sufficient to overcome the negative effect of activated Fur on feoB. In a tonB mutant, which lacks functional ferric transport systems, deletion of ompR severely impairs growth on rich medium not supplemented with iron, while the simultaneous deletion of ompC and ompF is not viable. These data, together with the observation of de-repression of the Fur regulon in an OmpC mutant, show that the porins play an important role in iron homeostasis. The work presented here also resolves a long-standing paradoxical observation of the effect of certain mutant envZ alleles on iron regulon.IMPORTANCEThe work presented here solved a long-standing paradox of the negative effects of certain missense alleles of envZ, which codes for kinase of the EnvZ/OmpR two component system, on the expression of ferric uptake genes. The data revealed that the constitutive envZ alleles activate the Feo- and OmpC-mediated ferrous uptake pathway to flood the cytoplasm with accessible ferrous iron. This activates the ferric uptake regulator, Fur, which inhibits ferric uptake system but cannot inhibit the feo operon due to the positive effect of activated EnvZ/OmpR. The data also revealed importance of porins in iron homeostasis.

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