title: Iron Release from the Siderophore Pyoverdine in Pseudomonas aeruginosa Involves Three New Actors: FpvC, FpvG, and FpvH.
abstract: Siderophores are iron chelators produced by bacteria to access iron, an essential nutriment. Pyoverdine (PVDI), the major siderophore produced by Pseudomonas aeruginosa PAO1, consists of a fluorescent chromophore linked to an octapeptide. The ferric form of PVDI is transported from the extracellular environment into the periplasm by the outer membrane transporter, FpvA. Iron is then released from the siderophore in the periplasm by a mechanism that does not involve chemical modification of the chelator but an iron reduction step. Here, we followed the kinetics of iron release from PVDI, in vitro and in living cells, by monitoring its fluorescence (as apo PVDI is fluorescent, whereas PVDI-Fe(III) is not). Deletion of the inner membrane proteins fpvG (PA2403) and fpvH (PA2404) affected55Fe uptake via PVDI and completely abolished PVDI-Fe dissociation, indicating that these two proteins are involved in iron acquisition via this siderophore. PVDI-Fe dissociation studies, using an in vitro assay, showed that iron release from this siderophore requires the presence of an iron reducer (DTT) and an iron chelator (ferrozine). In this assay, DTT could be replaced by the inner membrane protein, FpvG, and ferrozine by the periplasmic protein, FpvC, suggesting that FpvG acts as a reductase and FpvC as an Fe2+chelator in the process of PVDI-Fe dissociation in the periplasm of P. aeruginosa cells. This mechanism of iron release from PVDI is atypical among Gram-negative bacteria but seems to be conserved among Pseudomonads.
authors.affiliation: Université de Strasbourg , UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France.|CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France.
authors.forename: Géraldine
authors.initials: G
authors.lastname: Ganne
authors.affiliation: Université de Strasbourg , UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France.|CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France.
authors.forename: Karl
authors.initials: K
authors.lastname: Brillet
authors.affiliation: Université de Strasbourg , UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France.|CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France.
authors.forename: Beata
authors.initials: B
authors.lastname: Basta
authors.affiliation: Université de Strasbourg , UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France.|CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France.
authors.forename: Béatrice
authors.initials: B
authors.lastname: Roche
authors.affiliation: Université de Strasbourg , UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France.|CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Hoegy
authors.affiliation: Université de Strasbourg , UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France.|CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Gasser
authors.affiliation: Université de Strasbourg , UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France.|CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France.
authors.forename: Isabelle J
authors.identifier: 0000-0002-8351-1679
authors.initials: IJ
authors.lastname: Schalk
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D005798:Genes, Bacterial; D007501:Iron / Q000378:metabolism*; D009842:Oligopeptides / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism*; D017262:Siderophores / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D001426:Bacterial Proteins; D009842:Oligopeptides; D017262:Siderophores; C042453:pyoverdin; D007501:Iron