Expression dynamics of RpoS/Crl-dependent genes in Escherichia coli

Dudin, Omaya; Lacour, Stéphan; Geiselmann, Johannes

doi:10.1016/j.resmic.2013.07.002

Cited by 19 publications

(30 citation statements)

References 39 publications

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“…However, another recent report demonstrates that rpoS (indirectly) represses flhC transcription in E. coli strain BW25113 (16). We confirmed the negative regulation of fliA transcription by RpoS by using a green fluorescent protein (GFP) transcriptional fusion both in LB and M9 media (17). Consistently, an rpoS mutant also shows higher accumulation of the FliA (RpoF) protein during growth in LB medium (18).…”

Section: Quantitative Reverse Transcription-pcr (Qrt-pcr) Experimensupporting

confidence: 77%

“…These results also agree with previous transcriptomic studies (7,15,22) showing that RpoS alters a subset of genes in exponential phase, especially in minimal medium where RpoS accumulates to higher concentrations. Such specific regulatory events in fast-growing cells might rely on improved promoter recognition of a subset of genes (with better affinity for RpoS) and may be enhanced by the Crl protein (17,27). Since direct repression by a sigma factor is a rare mechanism, we screened for potential transcriptional repressors activated by RpoS and found two regulators, CsgD and CpxR, both of which repress cell motility.…”

Section: Discussionmentioning

confidence: 99%

“…In order to elucidate the mechanism by which CsgD and CpxR repress cell motility, we measured the expression kinetics of fliA, flgM, and tar in the corresponding mutant strains. These three fusions were selected among the reporter fusions for motility genes available in our GFP collection (30), because they presented sufficient activity above the promoterless GFP vector (17). The expression of fliA is strongly increased in both mutant strains during exponential phase in minimal medium (Fig.…”

Section: Rpos Represses the Transcription Of Flagellar Regulatorsmentioning

confidence: 99%

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Repression of Flagellar Genes in Exponential Phase by CsgD and CpxR, Two Crucial Modulators of Escherichia coli Biofilm Formation

et al. 2014

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e Escherichia coli adapts its lifestyle to the variations of environmental growth conditions, swapping between swimming motility or biofilm formation. The stationary-phase sigma factor RpoS is an important regulator of this switch, since it stimulates adhesion and represses flagellar biosynthesis. By measuring the dynamics of gene expression, we show that RpoS inhibits the transcription of the flagellar sigma factor, FliA, in exponential growth phase. RpoS also partially controls the expression of CsgD and CpxR, two transcription factors important for bacterial adhesion. We demonstrate that these two regulators repress the transcription of fliA, flgM, and tar and that this regulation is dependent on the growth medium. CsgD binds to the flgM and fliA promoters around their ؊10 promoter element, strongly suggesting direct repression. We show that CsgD and CpxR also affect the expression of other known modulators of cell motility. We propose an updated structure of the regulatory network controlling the choice between adhesion and motility.M icroorganisms adapt to changes in their environment in many different ways. Among others, they adjust gene expression, modify their metabolism, and change their surface properties by displaying particular surface proteins. The latter phenomenon is directly linked to the choice of a particular "lifestyle," adhesion (biofilm formation) or motility (planktonic growth). In Escherichia coli, expression of flagella at the cell surface predestines the cell for motility. More than 50 genes are involved in the synthesis of flagella. These genes are classified into three groups according to their temporal expression sequence. The master regulator of flagellar synthesis, FlhDC, is expressed first, and the corresponding genes constitute the class 1 flagellar operon. FlhDC activates the expression of class 2 genes, encoding the inner part of the flagellum as well as the flagellar sigma factor FliA ( 28 or F ) and the FlgM protein (anti-28 ). The class 3 genes are transcribed by 28 -RNA polymerase (RNAP) and encode the outer components of the flagellum as well as chemotaxis proteins (for a review, see reference 1).Flagellar synthesis is tightly controlled by several environmental conditions, including osmolarity (2) and temperature (3). Many of these environmental influences affect the transcription of flagellar genes and control in particular the expression of the master regulator, FlhDC. The regulators of the flhDC operon include cyclic AMP (cAMP)-cAMP receptor protein (CRP), H-NS (4), OmpR (2), LrhA (5), integration host factor (IHF) (2, 6), RpoN (7), and Fur (8). Other regulators affect cell motility by controlling fliA expression. These factors include NsrR (9), signaling molecules such as cyclic diguanylic acid (c-di-GMP) (reviewed in reference 10), the alarmone polyphosphate guanosine [(p)ppGpp] (11), and quorum-sensing molecules such as autoinducer-2 (AI-2) (12)(13)(14).Transcriptomic data show that the stationary sigma factor RpoS ( 38 ) represses the transcription of flagellar gene...

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Section: Quantitative Reverse Transcription-pcr (Qrt-pcr) Experimensupporting

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Section: Rpos Represses the Transcription Of Flagellar Regulatorsmentioning

confidence: 99%

See 1 more Smart Citation

Repression of Flagellar Genes in Exponential Phase by CsgD and CpxR, Two Crucial Modulators of Escherichia coli Biofilm Formation

et al. 2014

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“…One such regulator, the Crl protein [34], specifically increases binding of RpoS to core polymerase [35] through region 2 [36]. This activation is thus likely independent of RpoS-complexed promoter recognition at promoter sites in most cases, although it does play a role in recognition of some promoters [37]. In addition to the exponential phase, Crl is required for full RpoS-dependent expression of a subset of the RpoS regulon in early stationary phase [35].…”

Section: Expression In Exponential Phasementioning

confidence: 99%

“…These distinct effects help explain how RpoS, with low intrinsic affinity for holozyme and low intracellular concentration even in stationary phase, can be an effective global regulator. Since Crl effects are most pronounced at low RpoS concentrations and in the presence of RpoD [35], it is likely relevant in the exponential phase and may help explain why many genes are controlled by RpoS at this stage of growth [37]. Crl-mediated control of exponential phase genes may be relevant for pathogenesis, as RpoS levels are much higher in most O157:H7 strains in all phases of growth [38], although rpoS mutations appear common in many strains of this pathogenic serotype [39].…”

Section: Expression In Exponential Phasementioning

confidence: 99%

Elucidating the Function of the RpoS Regulon

Schellhorn

2014

Future Microbiol.

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Bacterial adaptation to suboptimal nutrient environments, including host and/or extreme environments, is subject to complex, coordinated control involving many proteins and RNAs. Among the γ-proteobacteria, which includes many pathogens, the RpoS regulon has been a key focus for many years. Although the RpoS regulator was first identified as a growth phase-dependent regulator, our current understanding of RpoS is now more nuanced as this central regulator also has roles in exponential phase, biofilm development, bacterial virulence and bacterial persistence, as well as in stress adaptation. Induction of RpoS can also exert substantial metabolic effects by negatively regulating key systems including flagella biosynthesis, cryptic phage gene expression and the tricarboxylic acid cycle. Although core RpoS-controlled metabolic functions are conserved, there are substantial differences in RpoS regulation even among closely related bacteria, indicating that regulatory plasticity may be an important aspect of RpoS regulation, which is important in evolutionary adaptation to specialized environments.

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Identification of novel genes involved in high hydrostatic pressure resistance of Escherichia coli

et al. 2019

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High hydrostatic pressure (HHP) is an interesting hurdle in minimal food processing that aims to synergistically combine different stresses to improve food microbiological safety and stability without compromising quality. For a proper understanding and design of hurdle technology, the cellular impact of the applied stresses on foodborne pathogens should be well-established. To study the mechanism of HHP-mediated cell injury and death, we screened for loss-of-function mutations in E. coli MG1655 that affected HHP sensitivity. More specifically, ca. 6,000 random transposon insertion mutants were individually exposed to HHP, after which the phenotype of the most resistant or sensitive mutations was confirmed by de novo gene deletions in the parental strain. We found that disruption of rbsK, rbsR, hdfR and crl decreased HHP resistance, while disruption of sucC and sucD (encoding subunits of the succinyl-CoA synthetase) increased HHP resistance. More detailed study of the tricarboxylic acid cycle enzymes encoded by the sdhCDAB-sucABCD operon surprisingly showed that disruption of the sucA or sucB gene (encoding subunits of the 2-oxoglutarate dehydrogenase complex) notably decreased HHP survival. We also found that the increased HHP resistance of a ∆sucC and ∆sucD mutant was mediated by increased basal RpoS activity levels, although it did not correlate with their heat resistance. Our results reveal that compromising TCA cycle enzymes can profoundly affect HHP resistance in E. coli.

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Expression dynamics of RpoS/Crl-dependent genes in Escherichia coli

Cited by 19 publications

References 39 publications

Repression of Flagellar Genes in Exponential Phase by CsgD and CpxR, Two Crucial Modulators of Escherichia coli Biofilm Formation

Repression of Flagellar Genes in Exponential Phase by CsgD and CpxR, Two Crucial Modulators of Escherichia coli Biofilm Formation

Elucidating the Function of the RpoS Regulon

Identification of novel genes involved in high hydrostatic pressure resistance of Escherichia coli

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