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.

Abstract

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 ion-exchange 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.

02040'99'01'03'05'07'09'11'13'15'17
Citations per Year

254 Citations

Semantic Scholar estimates that this publication has 254 citations based on the available data.

See our FAQ for additional information.

Cite this paper

@article{Ochsner1995RoleOT, title={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.}, author={Urs A. Ochsner and Adriana I. Vasil and Michael L. Vasil}, journal={Journal of bacteriology}, year={1995}, volume={177 24}, pages={7194-201} }