The glutamate-dependent acid resistance system in Escherichia coli: essential and dual role of the His–Asp phosphorelay RcsCDB/AF

Castanié-Cornet, Marie-Pierre; Treffandier, Hélène; Francez‐Charlot, Anne; Gutierrez, Claude; Cam, Kaymeuang

doi:10.1099/mic.0.29278-0

Cited by 62 publications

(55 citation statements)

References 42 publications

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“…The activity of the gadE promoter, which is partially dependent on itself for full activity (1,23), was reduced nearly 100-fold in the ⌬rcsB strain (Table 1). Thus, the effect of loss of RcsB on the regulation of GadE-dependent promoters may be due simply to loss of GadE expression, distinct from the reported situation in stationary phase (4). In addition, the GadE-independent promoters for safA, slp, gadW, gadY, mgtA, and ydeP showed significant reductions in acid-inducible activity in the ⌬rcsB strain ( Table 1).…”

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confidence: 82%

“…Several inducible acid resistance genes are under the control of the GadE-RcsB heterodimer (2,4,15,16). However, genes outside the GadE regulon also contribute to resistance to extreme acid shock and are induced by mild pH shock (16,(19)(20)(21).…”

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confidence: 99%

“…AR2 requires several regulators, including the central regulator GadE, to integrate signals from the EvgAS and PhoPQ two-component systems (3,(10)(11)(12)(13)17). RcsB, a regulator with a wide range of roles in many enteric bacteria (5), is essential for survival during extreme acid challenge (pH 2.5 or below) during stationary phase and regulates transcription of some AR2 genes by forming a heterodimer with GadE (2,4,15,16). RcsB also forms heterodimers with RcsA, TviA, and BglJ to regulate colanic acid synthesis, antigen VI expression, and sugar transport, respectively (26)(27)(28).…”

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RcsB Is Required for Inducible Acid Resistance in Escherichia coli and Acts at gadE-Dependent and -Independent Promoters

Johnson¹,

Burton²,

Gutiérrez³

et al. 2011

Journal of Bacteriology

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RcsB interacts with GadE to mediate acid resistance in stationary-phase Escherichia coli K-12. We show here that RcsB is also required for inducible acid resistance in exponential phase and that it acts on promoters that are not GadE regulated. It is also required for acid resistance in E. coli O157:H7.The glutamate-dependent acid resistance system AR2 of Escherichia coli is regulated by a regulatory network that responds to general stress, via the alternative sigma factor RpoS, and to low pH (8,13,17,18,20,22,25). AR2 requires several regulators, including the central regulator GadE, to integrate signals from the EvgAS and PhoPQ two-component systems (3,(10)(11)(12)(13)17). RcsB, a regulator with a wide range of roles in many enteric bacteria (5), is essential for survival during extreme acid challenge (pH 2.5 or below) during stationary phase and regulates transcription of some AR2 genes by forming a heterodimer with GadE (2, 4, 15, 16). RcsB also forms heterodimers with RcsA, TviA, and BglJ to regulate colanic acid synthesis, antigen VI expression, and sugar transport, respectively (26-28). Here we show that the inducible acid resistance of exponential-phase E. coli is also completely dependent on RcsB and that this resistance correlates with dependence of activation of the AR2 network on RcsB. We show that several AR2 genes that are not GadE regulated require RcsB and that RcsB must interact downstream of the sensor kinase EvgS but upstream of the first regulator, YdeO. These results suggest an additional role for RcsB in the activation of acid resistance and show that there is cross talk between the Rcs and EvgAS systems. We show that the role of RcsB extends to the pathogenic strain E. coli O157:H7 (Sakai).Induced acid resistance is rcsB dependent. A ⌬rcsB derivative of E. coli K-12 MG1655 was constructed as previously described (7). We determined the survival of this strain and the wild-type parent to extreme acid challenge in exponential phase, with and without induction by mild acidification (pH 5.7). Both strains grew at the same rate. Cells were grown, from overnight cultures diluted at least 500-fold, to an optical density at 600 nm (OD 600 ) of 0.2 in M9 with glucose (22.2 mM) and Casamino Acids (0.2% [wt/vol]), buffered with morpholinepropanesulfonic acid (MOPS) and morpholineethanesulfonic acid (MES) as described previously (M9supp) (1), and then incubated at pH 5.7 or pH 7 for 70 min before acid challenge at pH 2.4 for 2 h. We determined that under these conditions there are no detectable carryover effects from stationary phase on gene expression or cell survival. Cultures were always checked to ensure that the adjusted pH values remained constant for the entire experiment (data not shown). Survival was measured as previously described (1). Induction at pH 5.7 caused a significant increase in resistance in the wild-type strain (Fig. 1a). Survival of the ⌬rcsB strain was below the level of detection in both induced and uninduced cultures (Fig. 1a). To complement the rcsB deletion, we constructed p...

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confidence: 82%

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confidence: 99%

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confidence: 99%

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RcsB Is Required for Inducible Acid Resistance in Escherichia coli and Acts at gadE-Dependent and -Independent Promoters

Johnson¹,

Burton²,

Gutiérrez³

et al. 2011

Journal of Bacteriology

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“…The GAD system is the most effective system in protecting E. coli cells against low pH compared to other known AR mechanisms (10,11,27,56). The GAD system has three components: two GAD isozymes, GadA and GadB, and the gamma-aminobutyric acid (GABA)-glutamate antiporter GadC (18,31).…”

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Characterization of theEscherichia coliO157:H7 Sakai GadE Regulon

Bergholz

Whittam

2009

J Bacteriol

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Integrating laterally acquired virulence genes into the backbone regulatory network is important for the pathogenesis of Escherichia coli O157:H7, which has captured many virulence genes through horizontal transfer during evolution. GadE is an essential transcriptional activator of the glutamate decarboxylase (GAD) system, the most efficient acid resistance (AR) mechanism in E. coli. The full contribution of GadE to the AR and virulence of E. coli O157:H7 remains largely unknown. We inactivated gadE in E. coli O157:H7 Sakai and compared global transcription profiles of the mutant with that of the wild type in the exponential and stationary phases of growth. Inactivation of gadE significantly altered the expression of 60 genes independently of the growth phase and of 122 genes in a growth phase-dependent manner. Inactivation of gadE markedly downregulated the expression of gadA, gadB, and gadC and of many acid fitness island genes. Nineteen genes encoded on the locus of enterocyte effacement (LEE), including ler, showed a significant increase in expression upon gadE inactivation. Inactivation of ler in the ⌬gadE strain reversed the effect of gadE deletion on LEE expression, indicating that Ler is necessary for LEE repression by GadE. GadE is also involved in downregulation of LEE expression under conditions of moderately acidic pH. Characterization of AR of the ⌬gadE strain revealed that GadE is indispensable for a functional GAD system and for survival of E. coli O157:H7 in a simulated gastric environment. Altogether, these data indicate that GadE is critical for the AR of E. coli O157:H7 and that it plays an important role in virulence by downregulating expression of LEE.

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“…Since deletion of grvA was shown to upregulate GDAR genes (gadA, gadBC, gadE, gadW, gadX) during exponential-phase growth, the contribution of GrvA to GDAR was determined for exponential-phase cultures and was compared to that of the GDAR phenotype of stationary-phase cultures. In addition, since RcsB activates grvA transcription and is a dual regulator of GDAR system genes in E. coli K-12 (28,58,59), the interactions of rcsB and grvA in expression of the GDAR phenotype in EHEC O157:H7 were examined.…”

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confidence: 99%

Global Regulator of Virulence A (GrvA) Coordinates Expression of Discrete Pathogenic Mechanisms in Enterohemorrhagic Escherichia coli through Interactions with GadW-GadE

et al. 2016

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Global regulator of virulence A (GrvA) is a ToxR-family transcriptional regulator that activates locus of enterocyte effacement (LEE)-dependent adherence in enterohemorrhagic Escherichia coli (EHEC). LEE activation by GrvA requires the Rcs phosphorelay response regulator RcsB and is sensitive to physiologically relevant concentrations of bicarbonate, a known stimulant of virulence systems in intestinal pathogens. This study determines the genomic scale of GrvA-dependent regulation and uncovers details of the molecular mechanism underlying GrvA-dependent regulation of pathogenic mechanisms in EHEC. In a grvA-null background of EHEC strain TW14359, RNA sequencing analysis revealed the altered expression of over 700 genes, including the downregulation of LEE-and non-LEE-encoded effectors and the upregulation of genes for glutamate-dependent acid resistance (GDAR). Upregulation of GDAR genes corresponded with a marked increase in acid resistance. GrvA-dependent regulation of GDAR and the LEE required gadE, the central activator of GDAR genes and a direct repressor of the LEE. Control of gadE by GrvA was further determined to occur through downregulation of the gadE activator GadW. This interaction of GrvA with GadW-GadE represses the acid resistance phenotype, while it concomitantly activates the LEE-dependent adherence and secretion of immune subversion effectors. The results of this study significantly broaden the scope of GrvA-dependent regulation and its role in EHEC pathogenesis. IMPORTANCEEnterohemorrhagic Escherichia coli (EHEC) is an intestinal human pathogen causing acute hemorrhagic colitis and life-threatening hemolytic-uremic syndrome. For successful transmission and gut colonization, EHEC relies on the glutamate-dependent acid resistance (GDAR) system and a type III secretion apparatus, encoded on the LEE pathogenicity island. This study investigates the mechanism whereby the DNA-binding regulator GrvA coordinates activation of the LEE with repression of GDAR. Investigating how these systems are regulated leads to an understanding of pathogenic behavior and novel strategies aimed at disease prevention and control.

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The glutamate-dependent acid resistance system in Escherichia coli: essential and dual role of the His–Asp phosphorelay RcsCDB/AF

Cited by 62 publications

References 42 publications

RcsB Is Required for Inducible Acid Resistance in Escherichia coli and Acts at gadE-Dependent and -Independent Promoters

RcsB Is Required for Inducible Acid Resistance in Escherichia coli and Acts at gadE-Dependent and -Independent Promoters

Characterization of theEscherichia coliO157:H7 Sakai GadE Regulon

Global Regulator of Virulence A (GrvA) Coordinates Expression of Discrete Pathogenic Mechanisms in Enterohemorrhagic Escherichia coli through Interactions with GadW-GadE

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