title: Iron acquisition with the natural siderophore enantiomers pyochelin and enantio-pyochelin in Pseudomonas species.
abstract: The bacterial siderophore pyochelin is composed of salicylate and two cysteine-derived heterocycles, the second of which is modified by reduction and N-methylation during biosynthesis. In Pseudomonas aeruginosa, the first cysteine residue is converted to its D-isoform during thiazoline ring formation, whereas the second cysteine remains in its L-configuration. Stereochemistry is opposite in the Pseudomonas fluorescens siderophore enantio-pyochelin, in which the first ring originates from L-cysteine and the second ring from D-cysteine. Both siderophores promote growth of the producer organism during iron limitation and induce the expression of their biosynthesis genes by activating the transcriptional AraC-type regulator PchR. However, neither siderophore is functional as an iron carrier or as a transcriptional inducer in the other species, demonstrating that both processes are highly stereospecific. Stereospecificity of pyochelin/enantio-pyochelin-mediated iron uptake is ensured at two levels: (i) by the outer membrane siderophore receptors and (ii) by the cytosolic PchR regulators.
authors.affiliation: Département de Microbiologie Fondamentale, Université de Lausanne, Bâtiment Biophore, Lausanne, Switzerland.
authors.forename: Zeb A
authors.initials: ZA
authors.lastname: Youard
authors.forename: Nicolas
authors.initials: N
authors.lastname: Wenner
authors.forename: Cornelia
authors.initials: C
authors.lastname: Reimmann
mesh_terms: D000595:Amino Acid Sequence; D007501:Iron / Q000737:chemistry* / Q000378:metabolism*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry* / Q000378:metabolism; D011549:Pseudomonas / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017262:Siderophores / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013237:Stereoisomerism; D013844:Thiazoles / Q000737:chemistry* / Q000378:metabolism
chemical_list: D010636:Phenols; D017262:Siderophores; D013844:Thiazoles; C025316:pyochelin; D007501:Iron