Ferric uptake regulator Fur is conditionally essential in Pseudomonas aeruginosa

Martina Pasqua, Daniela Visaggio, Alessandra Lo Sciuto, Shirley Genah, Ehud Banin, Paolo Visca, Francesco Imperi

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54 Scopus citations


In Pseudomonas aeruginosa, the ferric uptake regulator (Fur) protein controls both metabolism and virulence in response to iron availability. Differently from other bacteria, attempts to obtain fur deletion mutants of P. aeruginosa failed, leading to the assumption that Fur is an essential protein in this bacterium. By investigating a P. aeruginosa conditional fur mutant, we demonstrate that Fur is not essential for P. aeruginosa growth in liquid media, biofilm formation, and pathogenicity in an insect model of infection. Conversely, Fur is essential for growth on solid media since Fur-depleted cells are severely impaired in colony formation. Transposonmediated random mutagenesis experiments identified pyochelin siderophore biosynthesis as a major cause of the colony growth defect of the conditional fur mutant, and deletion mutagenesis confirmed this evidence. Impaired colony growth of pyochelin-proficient Fur-depleted cells does not depend on oxidative stress, since Fur-depleted cells do not accumulate higher levels of reactive oxygen species (ROS) and are not rescued by antioxidant agents or overexpression of ROS-detoxifying enzymes. Ectopic expression of pch genes revealed that pyochelin production has no inhibitory effects on a fur deletion mutant of Pseudomonas syringae pv. tabaci, suggesting that the toxicity of the pch locus in Fur-depleted cells involves a P. aeruginosa-specific pathway(s).

Original languageEnglish
Article numbere00472-17
JournalJournal of Bacteriology
Issue number22
StatePublished - 15 Nov 2017

Bibliographical note

Publisher Copyright:
© 2017 American Society for Microbiology.


This work was supported by grants from the Italian Cystic Fibrosis Research Foundation (FFC10/2013), the Sapienza University of Rome (Ateneo 2015), and the Pasteur Institute-Cenci Bolognetti Foundation to F.I. E.B. was supported by a grant from the Dyna and Fala Weinstock Foundation.

FundersFunder number
Dyna and Fala Weinstock Foundation
Sapienza Università di Roma
Istituto Pasteur-Fondazione Cenci Bolognetti
Fondazione per la Ricerca sulla Fibrosi CisticaFFC10/2013


    • Biofilm
    • Colony formation
    • Infection
    • Iron uptake
    • Oxidative stress
    • Pseudomonas aeruginosa
    • Pyochelin
    • Siderophores


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