ClpXP Protease Controls Expression of the Type III Protein Secretion System through Regulation of RpoS and GrlR Levels in Enterohemorrhagic<i>Escherichia coli</i>

Iyoda, Sunao; Watanabe, Haruo

doi:10.1128/jb.187.12.4086-4094.2005

Cited by 91 publications

(162 citation statements)

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“…ClpXP controls the stability of a regulatory protein for the transcription of the flhDC operon. Iyoda & Watanabe (2005) studied the possibility that ClpXP may be directly involved in controlling the stability of the GrlR protein by comparing the levels of FLAG-tagged GrlR at different times after arresting protein synthesis in clpPX + and DclpPX cells. The GrlR-FLAG level in the clpPX + strain was unstable in stationary phase, suggesting that ClpXP is involved in controlling the stability of GrlR.…”

Section: Discussionmentioning

confidence: 99%

“…GrlA, which was originally identified as an activator of LEE operon expression, is antagonized by GrlR. The levels of GrlR are regulated in a growth-phase-dependent manner; GrlR levels are minimal when EHEC cells enter stationary phase, thereby facilitating expression of the LEE operon (Iyoda & Watanabe, 2005). To define the role of the GrlR-GrlA system in the control of flagellar expression by ClpXP, we measured the flhD-lacZ fusion activities in EHEC cells with DclpPX, DgrlR and/or DgrlA mutations as genetic backgrounds when they had entered stationary phase in DMEM.…”

Section: Regulation Of Flagellar Gene Expression By Clpxp Protease VImentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Our previous studies demonstrated that positive regulation of LEE expression by ClpXP is via two pathways, namely the RpoS-dependent and RpoS-independent pathways (Tomoyasu et al, 2005). ClpXP is involved in the expression of LEE at the control of the levels of the negative regulator GrlR in EHEC which could be the RpoS-independent pathway (Iyoda & Watanabe, 2005).In the course of phenotypic characterization of a ClpXPdepleted mutant derived from EHEC O157 : H7 Sakai, we have found that depletion of ClpXP results in overproduction of FliC, a major component of the flagellar filament, whereas there is a marked decrease in LEE-related proteins. The flagellum is an organelle consisting of three 3These authors contributed equally to this work.…”

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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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Section: Discussionmentioning

confidence: 99%

Section: Regulation Of Flagellar Gene Expression By Clpxp Protease VImentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

2011

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“…The E. coli strains and oligonucleotides used in this study are listed in Table 1 and Table 2, respectively. SKI-5142 is a lac-negative derivative of the EHEC O157:H7 Sakai (Iyoda and Watanabe, 2005) and was used as the wild-type strain. SKI-5350, which contains a chromosomal fliC′-lacZ translational fusion gene, was constructed as described previously (Saitoh et al, 2008) using the primer pair sets, FLIC-LACZf1-TL / LACZ-FRTr1 and LACZ-FRTf1 / FLIC-FRTr1.…”

Section: Methodsmentioning

confidence: 99%

A novel small regulatory RNA enhances cell motility in enterohemorrhagic Escherichia coli

Sudo

Soma

Muto

et al. 2014

J. Gen. Appl. Microbiol.

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Small regulatory RNAs (sRNAs) are conserved among a wide range of bacteria. They modulate the translational efficiency of target mRNAs through base-pairing with the help of RNA chaperone Hfq. The present study identified a novel sRNA, Esr41 (enterohemorrhagic Escherichia coli O157 small RNA #41), from an intergenic region of an enterohemorrhagic E. coli (EHEC) O157:H7 Sakai-specific sequence that is not present in the nonpathogenic E. coli K-12. Esr41 was detected as an RNA molecule approximately 70 nucleotides long with a 3 GC-rich palindrome sequence followed by a long poly(U), which is a characteristic of rho-independent terminators and is also a structural feature required for the action of Hfq. EHEC O157 harboring a multicopy plasmid carrying the esr41 gene increased cell motility and the expression of fliC, a gene encoding a major flagellar component. These results indicate that Esr41 stimulates fliC expression in EHEC O157. Furthermore, the increase in cell motility induced by Esr41 was also observed in the E. coli K-12, suggesting that target genes controlled by Esr41 are present in both EHEC O157 and K-12.Key words cell motility; EHEC O157 : H7 Sakai; flagella; small regulatory RNA IntroductionSmall regulatory RNAs (sRNAs) play crucial roles in bacterial stress responses and virulence (Gottesman, 2004;Papenfort and Vogel, 2010;Waters and Storz, 2009). Many sRNAs are induced under specific physiological conditions and control the expression of target genes, primarily at the post-transcriptional levels (Gottesman, 2004;Wassarman, 2002). sRNAs are classified as cis-acting sRNAs or transacting sRNAs. Cis-acting sRNAs are encoded on the strand opposite to the sense strand of the target gene and regulate the target gene expression by perfect base-pairing with its mRNA (Kawano et al., 2005). Trans-acting sRNAs are usually encoded in a different region from that of the target genes and regulate the expression of the target genes by partial base-pairing with their mRNAs. One major class of sRNA binds to RNA chaperone Hfq, which facilitates base-pairing between sRNA and the target mRNA to regulate its translation, mostly negatively but also positively in some cases (Aiba, 2007;Vogel and Luisi, 2011).A comprehensive identification of sRNA has been performed in many bacteria, such as Escherichia coli and None of the authors of this manuscript has any financial or personal relationship with other people or organizations that could inappropriately influence their work.

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σ^N‐dependent control of acid resistance and the locus of enterocyte effacement in enterohemorrhagic Escherichia coli is activated by acetyl phosphate in a manner requiring flagellar regulator FlhDC and the σ^S antagonist FliZ

et al. 2014

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In enterohemorrhagic Escherichia coli (EHEC), sigma factor N (σN) regulates glutamate-dependent acid resistance (GDAR) and the locus of enterocyte effacement (LEE); discrete genetic systems that are required for transmission and virulence of this intestinal pathogen. Regulation of these systems requires nitrogen regulatory protein C, NtrC, and is a consequence of NtrC-σN-dependent reduction in the activity of sigma factor S (σS). This study elucidates pathway components and stimuli for σN-directed regulation of GDAR and the LEE in EHEC. Deletion of fliZ, the product of which reduces σS activity, phenocopied rpoN (σN) and ntrC null strains for GDAR and LEE control, acid resistance, and adherence. Upregulation of fliZ by NtrC-σN was shown to be indirect and required an intact flagellar regulator flhDC. Activation of flhDC by NtrC-σN and FlhDC-dependent regulation of GDAR and the LEE was dependent on σN-promoter flhDP2, and a newly described NtrC upstream activator sequence. Addition of ammonium chloride significantly altered expression of GDAR and LEE, acid resistance, and adherence, independently of rpoN, ntrC, and the NtrC sensor kinase, ntrB. Altering the availability of NtrC phosphodonor acetyl phosphate by growth without glucose, with acetate addition, or by deletion of acetate kinase ackA, abrogated NtrC-σN-dependent control of flhDC, fliZ, GDAR, and the LEE.

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ClpXP Protease Controls Expression of the Type III Protein Secretion System through Regulation of RpoS and GrlR Levels in EnterohemorrhagicEscherichia coli

Cited by 91 publications

References 63 publications

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

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

A novel small regulatory RNA enhances cell motility in enterohemorrhagic Escherichia coli

σ^N‐dependent control of acid resistance and the locus of enterocyte effacement in enterohemorrhagic Escherichia coli is activated by acetyl phosphate in a manner requiring flagellar regulator FlhDC and the σ^S antagonist FliZ

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ClpXP Protease Controls Expression of the Type III Protein Secretion System through Regulation of RpoS and GrlR Levels in EnterohemorrhagicEscherichia coli

Cited by 91 publications

References 63 publications

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

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

A novel small regulatory RNA enhances cell motility in enterohemorrhagic Escherichia coli

σN‐dependent control of acid resistance and the locus of enterocyte effacement in enterohemorrhagic Escherichia coli is activated by acetyl phosphate in a manner requiring flagellar regulator FlhDC and the σS antagonist FliZ

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σ^N‐dependent control of acid resistance and the locus of enterocyte effacement in enterohemorrhagic Escherichia coli is activated by acetyl phosphate in a manner requiring flagellar regulator FlhDC and the σ^S antagonist FliZ