Global GacA-steered control of cyanide and exoprotease production in
            <i>Pseudomonas fluorescens</i>
            involves specific ribosome binding sites

Blumer, Caroline; Heeb, Stephan; Pessi, Gabriella; Haas, Dieter

doi:10.1073/pnas.96.24.14073

Cited by 238 publications

(267 citation statements)

References 37 publications

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“…The role of PsrA and RpoS in phenazine synthesis has so far not been studied in strain 30-84. The following hypothesis would reconcile the results in both strains: GacS/GacA could regulate phzI at the transcriptional level and phzR at the post-transcriptional level, since it was shown that GacA acts at both levels (Blumer et al, 1999;Pessi & Haas, 2001). In our gacS mutant, the presence of constitutively expressed phzR would result in an excess of PhzR mRNA that would overcome negative posttranscriptional regulation.…”

Section: Discussionmentioning

confidence: 90%

Regulatory roles of psrA and rpoS in phenazine-1-carboxamide synthesis by Pseudomonas chlororaphis PCL1391

et al. 2006

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Production of the secondary metabolite phenazine-1-carboxamide (PCN) by Pseudomonas chlororaphis PCL1391 is crucial for biocontrol activity against the phytopathogen Fusarium oxysporum f. sp. radicis lycopersici on tomato. Regulation of PCN production involves the two-component signalling system GacS/GacA, the quorum-sensing system PhzI/PhzR and the regulator PsrA. This paper reports that a functional rpoS is required for optimal PCN and N-hexanoyl-l-homoserine lactone (C6-HSL) production. Constitutive expression of rpoS is able to complement partially the defect of a psrA mutant for PCN and N-acylhomoserine lactone production. Western blotting shows that rpoS is regulated by gacS. Altogether, these results suggest the existence of a cascade consisting of gacS/gacA upstream of psrA and rpoS, which influence expression of phzI/phzR. Overproduction of phzR complements the effects on PCN and C6-HSL production of all mutations tested in the regulatory cascade, which shows that a functional quorum-sensing system is essential and sufficient for PCN synthesis. In addition, the relative amounts of PCN, phenazine-1-carboxylic acid and C6-HSL produced by rpoS and psrA mutants harbouring a constitutively expressed phzR indicate an even more complex network of interactions, probably involving other genes. Preliminary microarray analyses of the transcriptomics of the rpoS and psrA mutants support the model of regulation described in this study and allow identification of new genes that might be involved in secondary metabolism.

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Section: Discussionmentioning

confidence: 90%

Regulatory roles of psrA and rpoS in phenazine-1-carboxamide synthesis by Pseudomonas chlororaphis PCL1391

et al. 2006

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“…First, in a variety of other gram-negative bacteria, homologues of LetA/LetS activate gene expression indirectly by counteracting the effects of CsrA, a repressor of translation (8,12,20,21). Secondly, in PE-phase L. pneumophila, LetA/LetS and RpoS may mediate the decay of letE RNA (Fig.…”

Section: Discussionmentioning

confidence: 99%

The LetE Protein Enhances Expression of Multiple LetA/LetS-Dependent Transmission Traits by Legionella pneumophila

Bachman

Swanson

2004

Infect Immun

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Legionella pneumophila colonizes freshwater amoebae and can also replicate within alveolar macrophages. When their nutrient supply is exhausted, replicating bacteria become cytotoxic, motile, and infectious, which is thought to promote transmission to a new amoeba. The differentiation of L. pneumophila is coordinated by the sigma factors RpoS and FliA and the two-component regulator LetA/LetS and is enhanced by the letE locus. Here we demonstrate that letE promotes motility by increasing expression of the flagellin gene flaA but has little impact on the transcription of fliA, the flagellar sigma factor gene. In addition to promoting motility, letE induces the characteristic shape, pigment, and heat resistance of stationary-phase L. pneumophila. To gain insight into how letE promotes the expression of the transmission phenotype, we designed molecular genetic experiments to discriminate between the following three models: letE mutations are polar on milX; letE encodes a small novel protein; or, by analogy to csrB, letE encodes a regulatory RNA that sequesters CsrA to relieve repression. We report that letE encodes an activator protein, as it does not complement an Escherichia coli csrB mutant, it directs the synthesis of an ϳ12-kDa polypeptide, and a letE nonsense mutation eliminates function. A monocistronic letE RNA is abundant during the exponential phase, and its decay during the stationary phase requires RpoS and LetA/LetS. We also discuss how the LetE protein may interact with LetA/LetS and CsrA to enhance L. pneumophila differentiation to a transmissible form.

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“…The resulting 635-bp upstream and 955-bp downstream fragments were cleaved with HindIII ϩ BamHI, and BamHI ϩ EcoRI, respectively, and inserted into the suicide plasmid pME3087 (14) cut with HindIII ϩ EcoRI. The resulting plasmid pME7315 was introduced into strains CHA0, CHA207, CHA805, CHA825, CHA826, and CHA827 (13,14,18) to generate, via homologous recombination, the corresponding mutants CHA1141 (⌬rsmX), CHA1142 (⌬rsmX, hcnAЈ-ЈlacZ), CHA1143 (⌬rsmX, aprAЈ-ЈlacZ), CHA1144 (⌬rsmX ⌬rsmY ⌬rsmZ), CHA1145 (⌬rsmX ⌬rsmY ⌬rsmZ, hcnAЈ-ЈlacZ), and CHA1146 (⌬rsmX ⌬rsmY ⌬rsmZ, aprAЈ-ЈlacZ). An rsmX-lacZ fusion was constructed by PCR amplification of the 312-bp rsmX promoter region with primers PROF and PROR1 (Table 3).…”

Section: Methodsmentioning

confidence: 99%

“…In E. coli, CsrA regulates the utilization of carbon sources, glycogen synthesis, biofilm formation, and motility (7)(8)(9)(10)(11), whereas in Erwinia carotovora, the CsrA homolog RsmA (repressor of secondary metabolism) controls the expression of extracellular enzymes and type III secretion (12). The similar RsmA and RsmE proteins of the plant-beneficial root-colonizing biocontrol strain CHA0 of Pseudomonas fluorescens negatively regulate the synthesis of extracellular antifungal secondary metabolites (13)(14)(15). Small noncoding RNAs, such as CsrB and CsrC of E. coli (8,16), RsmB of E. carotovora (17), or RsmZ and RsmY of P. fluorescens (14,18), bind multiple CsrA͞RsmA molecules with high affinity and thereby allow translation of mRNAs, which are repressed by CsrA or RsmA.…”

mentioning

confidence: 99%

Three small RNAs jointly ensure secondary metabolism and biocontrol in Pseudomonas fluorescens CHA0

Kay

Dubuis

Haas

2005

Proc. Natl. Acad. Sci. U.S.A.

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In many Gram-negative bacteria, the GacS͞GacA two-component system positively controls the expression of extracellular products or storage compounds. In the plant-beneficial rhizosphere bacterium Pseudomonas fluorescens CHA0, the GacS͞GacA system is essential for the production of antibiotic compounds and hence for biological control of root-pathogenic fungi. The small (119-nt) RNA RsmX discovered in this study, together with RsmY and RsmZ, forms a triad of GacA-dependent small RNAs, which sequester the RNA-binding proteins RsmA and RsmE and thereby antagonize translational repression exerted by these proteins in strain CHA0. This small RNA triad was found to be both necessary and sufficient for posttranscriptional derepression of biocontrol factors and for protection of cucumber from Pythium ultimum. The same three small RNAs also positively regulated swarming motility and the synthesis of a quorum-sensing signal, which is unrelated to N-acylhomoserine lactones, and which autoinduces the Gac͞Rsm cascade. Expression of RsmX and RsmY increased in parallel throughout cell growth, whereas RsmZ was produced during the late growth phase. This differential expression is assumed to facilitate fine tuning of GacS͞A-controlled cell population density-dependent regulation in P. fluorescens.GacA ͉ posttranscriptional control

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Global GacA-steered control of cyanide and exoprotease production in Pseudomonas fluorescens involves specific ribosome binding sites

Cited by 238 publications

References 37 publications

Regulatory roles of psrA and rpoS in phenazine-1-carboxamide synthesis by Pseudomonas chlororaphis PCL1391

Regulatory roles of psrA and rpoS in phenazine-1-carboxamide synthesis by Pseudomonas chlororaphis PCL1391

The LetE Protein Enhances Expression of Multiple LetA/LetS-Dependent Transmission Traits by Legionella pneumophila

Three small RNAs jointly ensure secondary metabolism and biocontrol in Pseudomonas fluorescens CHA0

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