title: Pyochelin enantiomers and their outer-membrane siderophore transporters in fluorescent pseudomonads: structural bases for unique enantiospecific recognition.
abstract: Pyochelin (Pch) and enantiopyochelin (EPch) are enantiomeric siderophores, with three chiral centers, produced under iron limitation conditions by Pseudomonas aeruginosa and Pseudomonas fluorescens , respectively. After iron chelation in the extracellular medium, Pch-Fe and EPch-Fe are recognized and transported by their specific outer-membrane transporters: FptA in P. aeruginosa and FetA in P. fluorescens . Structural analysis of FetA-EPch-Fe and FptA-Pch-Fe, combined with mutagenesis and docking studies revealed the structural basis of the stereospecific recognition of these enantiomers by their respective transporters. Whereas FetA and FptA have a low sequence identity but high structural homology, the Pch and EPch binding pockets do not share any structural homology, but display similar physicochemical properties. The stereospecific recognition of both enantiomers by their corresponding transporters is imposed by the configuration of the siderophore's C4'' and C2'' chiral centers. This recognition involves specific hydrogen bonds between the Arg91 guanidinium group and EPch-Fe for FetA and between the Leu117-Leu116 main chain and Pch-Fe for FptA. FetA and FptA are the first membrane receptors to be structurally described with opposite binding enantioselectivities for their ligands, giving insights into the structural basis of their enantiospecificity.
authors: UMR 7242 Biotechnologie et Signalisation Cellulaire, Université de Strasbourg-CNRS, Irebs-ESBS, Boulevard Sébastien Brant, 67412 Illkirch, France.
authors: Karl
authors: K
authors: Brillet
authors: Cornelia
authors: C
authors: Reimmann
authors: Gaëtan L A
authors: GL
authors: Mislin
authors: Sabrina
authors: S
authors: Noël
authors: Didier
authors: D
authors: Rognan
authors: Isabelle J
authors: IJ
authors: Schalk
authors: David
authors: D
authors: Cobessi
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D005453:Fluorescence; D008958:Models, Molecular; D015394:Molecular Structure; D010636:Phenols / Q000737:chemistry* / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000737:chemistry*; D011551:Pseudomonas fluorescens / Q000737:chemistry*; D013237:Stereoisomerism; D013844:Thiazoles / Q000737:chemistry* / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; D010636:Phenols; D013844:Thiazoles; C025316:pyochelin