Regulation of bacterial motility in response to low pH in Escherichia coli: the role of H-NS protein

Soutourina, Olga; Krin, Evelyne; Laurent‐Winter, Christine; Hommais, Florence; Danchin, Antoine; Bertin, Philippe

doi:10.1099/00221287-148-5-1543

Cited by 62 publications

(55 citation statements)

References 58 publications

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“…These data suggest that the cydB strain is less motile than wild type. Diminished H-NS activity has been shown to decrease activity of the FlhDC master regulator of flagella biosynthesis (56). The current observation that both FlhDC activity and motility are diminished in a cydB strain could explain in part previous data where loss of the CydDC cysteine/glutathione exporter, which also results in the loss of a functional cytochrome bd, causes decreased motility (27).…”

Section: Loss Of Cydb Causes Diminished Respirationsupporting

confidence: 69%

Compensations for Diminished Terminal Oxidase Activity in Escherichia coli

Shepherd

Sanguinetti

Cook

et al. 2010

Journal of Biological Chemistry

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Escherichia coli possesses cytochrome bo (CyoABCDE), cytochrome bd-I (CydAB), and cytochrome bd-II (AppBC) quinol oxidases, all of which can catalyze the terminal step in the aerobic respiratory chain, the reduction of oxygen by ubiquinol. Although CydAB has a role in the generation of ⌬pH, AppBC has been proposed to alleviate the accumulation of electrons in the quinone pool during respiratory stress via electroneutral ubiquinol oxidation. A cydB mutant strain exhibited lower respiration rates while maintaining a wild type growth rate. Transcriptomic analysis revealed a dramatic up-regulation of AppBC in the cydB strain, accompanied by the induction of genes involved in glutamate/␥-aminobutyric acid (GABA) antiport, the GABA shunt, the glyoxylate shunt, respiration (including appBC), motility, and osmotic stress. Transcription factor modeling suggests that the underpinning regulation is largely controlled by H-NS, GadX, FlhDC, and AppY. The transcriptional adaptations imply that cydB cells contribute to the proton motive force via consumption of intracellular protons and glutamate/GABA antiport. Indeed, supplementation of culture medium with L-glutamate stimulates growth in a cydB strain. Phenotype analyses of the cydB strain confirm decreased motility and elevated acid resistance and also an elevated cytochrome d spectroscopic signal in cells grown at low pH. We propose a mechanism via which E. coli can compensate for the loss of cytochrome bd-I activity; cytochrome bd-II-mediated quinol oxidation prevents the accumulation of NADH, whereas GABA synthesis/antiport maintains the proton motive force for ATP production.

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Section: Loss Of Cydb Causes Diminished Respirationsupporting

confidence: 69%

Compensations for Diminished Terminal Oxidase Activity in Escherichia coli

Shepherd

Sanguinetti

Cook

et al. 2010

Journal of Biological Chemistry

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“…As the CRP binding sites on the ompT promoter were predicted based on the consensus CRP binding site from E. coli, the promoter region of the flhDC gene (encoding the master regulator of the flagella operon), which is known to interact directly with CRP, was used as a positive control. V. cholerae CRP was shown to bind specifically to a 200 bp fragment of this promoter that contains a consensus CRP binding site (Soutourina et al, 1999) (Fig. 4A).…”

Section: Direct Interaction Of Crp With the Ompt Promotermentioning

confidence: 99%

ToxR interferes with CRP‐dependent transcriptional activation of ompT in Vibrio cholerae

Merrell

Camilli

et al. 2002

Molecular Microbiology

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SummaryIn pathogenic Vibrio cholerae, the transmembrane DNA-binding protein ToxR co-ordinates the expression of over 20 genes, including those encoding important virulence factors such as cholera toxin and the toxin-co-regulated pilus. The outer membrane protein OmpT is the only member of the ToxR regulon known to be repressed by ToxR. In this study, we examined the environmental conditions that regulate OmpT expression and demonstrated that ompT transcription is upregulated 14-fold when the bacteria enter late log phase from early log phase. Deletion of the crp gene completely abolishes OmpT expression. Comparison of ompT transcription levels in the isogenic crp -, toxR -and crp -toxR -mutants revealed that (i) in the absence of ToxR, constitutive high-level ompT transcription is dependent on cAMP receptor protein (CRP); (ii) ToxR not only interferes with CRPdependent ompT activation, but also abolishes the CRP-independent, basal level ompT transcription; thus, the mechanism by which ToxR represses ompT transcription involves both antiactivation and direct repression; (iii) both CRP and ToxR are required for the regulation of OmpT expression by growth phase. To provide further insights into the molecular mechanism of CRP-dependent activation of ompT transcription, we demonstrated that CRP-dependent activation requires a CRP binding site centred at -310 of the ompT promoter, without which the interaction of CRP with other CRP binding site(s) more proximal to the promoter results in repression. Mutations in two regions on CRP (AR1 and AR2) that directly

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“…Since the FlhD/FlhC is essential for transcription of all the genes in the flagellar cascade, it is also called a master regulator. Transcription of the flhDC operon is known to be regulated by a number of global regulatory signals in E. coli and related bacteria (Iyoda et al, 2006;Shi et al, 1993;Soutourina et al, 2002). In addition, the FlhD/FlhC is modulated at the post-transcriptional and post-translational levels (Tomoyasu et al, 2003;Wozniak et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Dual regulatory pathways of flagellar gene expression by ClpXP protease in enterohaemorrhagic Escherichia coli

2011

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In enterobacteria such as Escherichia coli and Salmonella species, flagellar biogenesis is strictly dependent upon the master regulator flhDC. Here, we demonstrate that in enterohaemorrhagic E. coli (EHEC), the flagellar regulon is controlled by ClpXP, a member of the ATP-dependent protease family, through two pathways: (i) post-translational control of the FlhD/FlhC master regulator and (ii) transcriptional control of the flhDC operon. Both FlhD and FlhC proteins accumulated markedly following ClpXP depletion, and their half-lives were significantly longer in the mutant cells, suggesting that ClpXP is responsible for degrading FlhD and FlhC proteins, leading to downregulation of flagellar expression. ClpXP was involved in regulating the transcription of the flhD promoter only when the cells had entered stationary phase in a culture medium that markedly induced expression of the locus of enterocyte effacement (LEE). Comparative analyses of transcription from the flhD promoter in EHEC cells with different genetic backgrounds suggested that the downregulation of flhDC expression by ClpXP is dependent on the LEE-encoded GrlR-GrlA system. We have also shown that the degradation of FlhD and FlhC by ClpXP is responsible for downregulating flagellar expression even when LEE expression is induced. INTRODUCTIONEnterohaemorrhagic Escherichia coli (EHEC) O157 : H7 is a causative agent of bloody diarrhoea, non-bloody diarrhoea and haemolytic uraemic syndrome in humans (Akashi et al., 1994). EHEC colonizes the intestine and causes a destructive lesion of the intestinal enterocyte, referred to as the attaching and effacing (A/E) lesion. The genes responsible for the formation of A/E lesions are located on a pathogenicity island called the locus of enterocyte effacement (LEE). The LEE genes are organized into five operons which are under strict control (Friedberg et al., 1999). Three regulators, Ler, GrlR and GrlA, encoded in the LEE have been well characterized: Ler is a central activator of the transcription of most LEE genes, and GrlA and GrlR are positive and negative regulators, respectively, for ler transcription (Iyoda et al., 2006). In addition to the control by those regulatory elements encoded in the LEE, various regulatory elements encoded outside the locus, such as BipA (Grant et al., 2003), IHF (Friedberg et al., 1999), H-NS (Bustamante et al., 2001Umanski et al., 2002) and QseA (Sperandio et al., 2002), are involved in the control of LEE expression. We have previously reported that the ATP-dependent protease, ClpXP, is a positive regulator of LEE expression (Tomoyasu et al., 2005). ClpXP protease is composed of a ClpP proteolytic component and a ClpX component that binds substrate proteins, denatures them and translocates the unfolded polypeptides into the ClpP degradation chamber (Ortega et al., 2000). ClpXP is a bipartite protease responsible for degrading certain key regulatory proteins such as RpoS, which is a stationary-phase-specific sigma factor for RNA polymerase, and aberrant translation products bearin...

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Regulation of bacterial motility in response to low pH in Escherichia coli: the role of H-NS protein

Cited by 62 publications

References 58 publications

Compensations for Diminished Terminal Oxidase Activity in Escherichia coli

Compensations for Diminished Terminal Oxidase Activity in Escherichia coli

ToxR interferes with CRP‐dependent transcriptional activation of ompT in Vibrio cholerae

Dual regulatory pathways of flagellar gene expression by ClpXP protease in enterohaemorrhagic Escherichia coli

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