Zinc and iron regulate translation of the gene encoding <i>Pseudomonas aeruginosa</i> elastase

Brumlik, Michael J.; Storey, Douglas G.

doi:10.1111/j.1365-2958.1992.tb01476.x

Cited by 45 publications

(42 citation statements)

References 44 publications

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“…For example, iron and zinc have been shown to regulate the expression of elastase (Brumlik and Storey, 1992). Iron concentration also regulates the transcription of toxA, the structural gene of exotoxin A.…”

Section: Discussionmentioning

confidence: 99%

Regulation of the xcp secretion pathway by multiple quorum‐sensing modulons in Pseudomonas aeruginosa

Chapon

Akrim

Latifi

et al. 1997

Molecular Microbiology

129

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SummaryThe virulence of the opportunistic pathogen Pseudomonas aeruginosa is largely dependent upon the extracellular production of a number of secreted proteins with toxic or degradative activities. The synthesis of several exoenzymes is controlled in a cell-densitydependent manner by two interlinked quorum-sensing systems. Their secretion across the outer membrane occurs through the Xcp translocation machinery. The xcp locus located at 40 min on the chromosome consists of two divergently transcribed operons, namely xcpPQ and xcpR to xcpZ. In this study, transcriptional fusions were constructed between the xcpP and xcpR genes and the lacZ reporter. Transcriptional activation of the xcpP and xcpR genes in P. aeruginosa is growth-phase dependent and the lasR-lasI autoinduction system is required for this control. In the heterologous host Escherichia coli, the lasR gene product, together with its cognate autoinducer N-(3-oxododecanoyl)-L-homoserine lactone (OdDHL), activates both the xcpP-lacZ and the xcpR-lacZ gene fusion. The second P. aeruginosa quorum-sensing modulon rhlR-rhlI (vsmR-vsmI ) is also involved in the control of the xcp genes. Expression of the lacZ fusions is strongly reduced in PANO67, a pleiotropic mutant defective in the production of N-acyl-homoserine lactones responsible for the activation of RhlR. Furthermore, introduction of the lasR mutation in PANO67 results in additional diminution of xcpR transcription, indicating that the two systems can regulate their target genes independently. These data demonstrate that expression of the xcp secretion system depends on a complex regulatory network involving cell-cell signalling which controls production and secretion of virulence-associated factors.

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Section: Discussionmentioning

confidence: 99%

Regulation of the xcp secretion pathway by multiple quorum‐sensing modulons in Pseudomonas aeruginosa

Chapon

Akrim

Latifi

et al. 1997

Molecular Microbiology

129

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“…It is unclear whether PA-Fur utilizes alternative divalent cations in vivo to become an active repressor. The availability of zinc may play a role in pathogenesis, since this metal regulates the expression of elastase, which is a zincmetalloprotease and is believed to be one of the major virulence factors of P. aeruginosa (9).…”

Section: Discussionmentioning

confidence: 99%

Role of the ferric uptake regulator of Pseudomonas aeruginosa in the regulation of siderophores and exotoxin A expression: purification and activity on iron-regulated promoters

1995

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The cloned Pseudomonas aeruginosa fur (ferric uptake regulator) gene was overexpressed in P. aeruginosa by using a T7 expression system, and the Fur protein (PA-Fur) was purified by using a combination of ionexchange chromatography and metal affinity chromatography. The DNA binding activity of the PA-Fur protein was confirmed by gel mobility shift assays and DNase I footprints of the synthetic DNA fragment GATAAT GATAATCATTATC, representing a perfect ''Fur box''. In addition, it was shown that PA-Fur is capable of binding to promoter and operator determinants of the tightly iron-regulated Escherichia coli fepA-fes enterobactin gene system. The activity of PA-Fur on the promoters of iron-regulated genes involved in the production of two siderophores, pyochelin and pyoverdin, and in the expression of exotoxin A was investigated. Data indicating that the promoters of the pchR gene, encoding a transcriptional activator for pyochelin synthesis, and of the pvdS gene, encoding a positive regulator for pyoverdin production, are specifically recognized by Fur-Fe(II) are presented, suggesting that PA-Fur represses expression of pchR and pvdS during growth in an iron-replete environment. However, neither the promoter region of the gene encoding exotoxin A (toxA) nor the promoters of the regAB operon, required for toxA expression, interacted with high concentrations of purified PA-Fur. These data indicate that iron regulation of exotoxin A production involves additional factors which may ultimately be under the control of PA-Fur.

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“…6). An enhanced activity of elastase at decreased iron concentration has been reported (Bjorn et al, 1979;Brumlik & Storey, 1992;Storey et al, 1992). In host cells, elastase is able to specifically cleave transferrin, an animal iron carrier.…”

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confidence: 97%

Iron deficiency leads to inhibition of oxygen transfer and enhanced formation of virulence factors in cultures of Pseudomonas aeruginosa PAO1

2003

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Pseudomonas aeruginosa PAO1 was recently found to exhibit two remarkable physiological responses to oxidative stress: (1) a strong reduction in the efficiency of oxygen transfer from the gas phase into the liquid phase, thus causing oxygen limitation in the culture and (2) formation of a clear polysaccharide capsule on the cell surface. In this work, it has been shown that the iron concentration in the culture plays a crucial role in evoking these phenomena. The physiological responses of two P. aeruginosa PAO1 isolates (NCCB 2452 and ATCC 15692) were examined in growth media with varied iron concentrations. In a computer-controlled bioreactor cultivation system for controlled dissolved oxygen tension (pO 2 ), a strong correlation between the exhaustion of iron and the onset of oxygen limitation was observed. The oxygen transfer rate of the culture, characterized by the volumetric oxygen transfer coefficient, k L a, significantly decreased under iron-limited conditions. The formation of alginate and capsule was more strongly affected by iron concentration than by oxygen concentration. The reduction of the oxygen transfer rate and the subsequent oxygen limitation triggered by iron deficiency may represent a new and efficient way for P. aeruginosa PAO1 to adapt to growth conditions of iron limitation. Furthermore, the secretion of proteins into the culture medium was strongly enhanced by iron limitation. The formation of the virulence factor elastase and the iron chelators pyoverdine and pyochelin also significantly increased under iron-limited conditions. These results have implications for lung infection of cystic fibrosis patients by P. aeruginosa in view of the prevalence of iron limitation at the site of infection and the respiratory failure leading to death.

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Zinc and iron regulate translation of the gene encoding Pseudomonas aeruginosa elastase

Cited by 45 publications

References 44 publications

Regulation of the xcp secretion pathway by multiple quorum‐sensing modulons in Pseudomonas aeruginosa

Regulation of the xcp secretion pathway by multiple quorum‐sensing modulons in Pseudomonas aeruginosa

Role of the ferric uptake regulator of Pseudomonas aeruginosa in the regulation of siderophores and exotoxin A expression: purification and activity on iron-regulated promoters

Iron deficiency leads to inhibition of oxygen transfer and enhanced formation of virulence factors in cultures of Pseudomonas aeruginosa PAO1

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