Iron transport and regulation, cell signalling and genomics: lessons from <i>Escherichia coli</i> and <i>Pseudomonas</i>

Visca, Paolo; Leoni, Livia; Wilson, Megan J.; Lamont, Iain L.

doi:10.1046/j.1365-2958.2002.03088.x

Cited by 246 publications

(267 citation statements)

References 79 publications

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“…Interestingly, the microarray analysis revealed that expression of the gene encoding the iron-regulated sigma factor PvdS was increased 11-fold in the rsmA mutant compared to wild-type. The fact that PvdS levels were increased in the rsmA mutant may explain the increase in expression of the pvd genes (Beare et al, 2003;Visca et al, 2002) but not the pch operon. Transcription of pchABCDE and fptA is activated by the AraC-like regulator PchR in the presence of pyochelin and repressed in the absence of pyochelin (Heinrichs & Poole, 1996).…”

Section: Resultsmentioning

confidence: 99%

Influence of the regulatory protein RsmA on cellular functions in Pseudomonas aeruginosa PAO1, as revealed by transcriptome analysis

et al. 2006

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RsmA is a posttranscriptional regulatory protein in Pseudomonas aeruginosa that works in tandem with a small non-coding regulatory RNA molecule, RsmB (RsmZ), to regulate the expression of several virulence-related genes, including the N-acyl-homoserine lactone synthase genes lasI and rhlI, and the hydrogen cyanide and rhamnolipid biosynthetic operons. Although these targets of direct RsmA regulation have been identified, the full impact of RsmA on cellular activities is not as yet understood. To address this issue the transcriptome profiles of P. aeruginosa PAO1 and an isogenic rsmA mutant were compared. Loss of RsmA altered the expression of genes involved in a variety of pathways and systems important for virulence, including iron acquisition, biosynthesis of the Pseudomonas quinolone signal (PQS), the formation of multidrug efflux pumps, and motility. Not all of these effects can be explained through the established regulatory roles of RsmA. This study thus provides both a first step towards the identification of further genes under RsmA posttranscriptional control in P. aeruginosa and a fuller understanding of the broader impact of RsmA on cellular functions.

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Section: Resultsmentioning

confidence: 99%

Influence of the regulatory protein RsmA on cellular functions in Pseudomonas aeruginosa PAO1, as revealed by transcriptome analysis

et al. 2006

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“…The production of siderophores is a metabolically costly process that is tightly regulated to ensure that production only occurs when siderophores are needed (24,39,67). One mechanism that bacteria use to regulate siderophore production is by controlling expression of the siderophore production genes via an extracytoplasmic function (ECF) factor (39,67). The siderophore produced by A. tumefaciens (a polyketide/nonribosomal peptide molecule encoded by a large gene cluster of almost 53 kb) is controlled by such a factor, which we have designated I (54).…”

Section: Discussionmentioning

confidence: 99%

Antiparallel and Interlinked Control of Cellular Iron Levels by the Irr and RirA Regulators of Agrobacterium tumefaciens

Hibbing

Fuqua

2011

J Bacteriol

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The plant pathogen Agrobacterium tumefaciens encodes predicted iron-responsive regulators, Irr and RirA, that function in several other bacteria to control the response to environmental iron levels. Deletion mutations of irr and rirA, alone and in combination, were evaluated for their impact on cellular iron response. Growth was severely diminished in the ⌬irr mutant under iron-limiting conditions, but reversed to wild-type levels in an ⌬irr ⌬rirA mutant. The level of uncomplexed iron in the ⌬irr mutant was decreased, whereas the ⌬rirA mutant exhibited elevated iron levels. Sensitivity of the ⌬irr and ⌬rirA mutants to iron-activated antimicrobial compounds generally reflected their uncomplexed-iron levels. Expression of genes that encode iron uptake systems was decreased in the ⌬irr mutant, whereas that of iron utilization genes was increased. Irr function required a trihistidine repeat likely to mediate interactions with heme. Iron uptake genes were derepressed in the ⌬rirA mutant. In the ⌬irr ⌬rirA mutant, iron uptake and utilization genes were derepressed, roughly combining the phenotypes of the single mutants. Siderophore production was elevated in the rirA mutant, but most strongly regulated by an RirA-controlled sigma factor. Expression of rirA itself was regulated by Irr, RirA, and iron availability, in contrast to irr expression, which was relatively stable in the different mutants. These studies suggest that in A. tumefaciens, the Irr protein is most active under low-iron conditions, inhibiting iron utilization and activating iron acquisition, while the RirA protein is active under high-iron conditions, repressing iron uptake.

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“…Full expression often requires the presence of the siderophore. By a variety of different mechanisms involving extracellular cytoplasmic function (ECF) sigma/anti-sigma factors, two-component regulatory systems or AraC-type regulators, the siderophore induces the expression of genes necessary for its uptake and, in certain cases, also for its biosynthesis (Poole & McKay, 2003;Visca et al, 2002). In this type of regulation, also known as siderophore-mediated signalling , perception of the siderophore can occur either at the cell surface, in the periplasm, or in the cytoplasm; examples are provided by pyoverdine-, enterobactin-and pyochelinmediated signalling in the Gram-negative bacterium Pseudomonas aeruginosa.…”

Section: Introductionmentioning

confidence: 99%

Ferripyochelin uptake genes are involved in pyochelin-mediated signalling in Pseudomonas aeruginosa

2007

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In response to iron starvation, Pseudomonas aeruginosa produces the siderophore pyochelin. When secreted to the extracellular environment, pyochelin chelates iron and transports it to the bacterial cytoplasm via its specific outer-membrane receptor FptA and the inner-membrane permease FptX. Exogenously added pyochelin also acts as a signal which induces the expression of the pyochelin biosynthesis and uptake genes by activating PchR, a cytoplasmic regulatory protein of the AraC/XylS family. The importance of ferripyochelin uptake genes in this regulation was evaluated. The fptA and fptX genes were shown to be part of the fptABCX ferripyochelin transport operon, which is conserved in Burkholderia sp. and Rhodospirillum rubrum. The fptB and fptC genes were found to be dispensable for utilization of pyochelin as an iron source, for signalling and for pyochelin production. By contrast, mutations in fptA and fptX not only interfered with pyochelin utilization, but also affected signalling and diminished siderophore production. It is concluded from this that pyochelin-mediated signalling operates to a large extent via the ferripyochelin transport system.

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Iron transport and regulation, cell signalling and genomics: lessons from Escherichia coli and Pseudomonas

Cited by 246 publications

References 79 publications

Influence of the regulatory protein RsmA on cellular functions in Pseudomonas aeruginosa PAO1, as revealed by transcriptome analysis

Influence of the regulatory protein RsmA on cellular functions in Pseudomonas aeruginosa PAO1, as revealed by transcriptome analysis

Antiparallel and Interlinked Control of Cellular Iron Levels by the Irr and RirA Regulators of Agrobacterium tumefaciens

Ferripyochelin uptake genes are involved in pyochelin-mediated signalling in Pseudomonas aeruginosa

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