3QLB image
Deposition Date 2011-02-02
Release Date 2011-12-07
Last Version Date 2024-11-20
Entry Detail
PDB ID:
3QLB
Keywords:
Title:
Enantiopyochelin outer membrane TonB-dependent transporter from Pseudomonas fluorescens bound to the ferri-enantiopyochelin
Biological Source:
Source Organism:
Method Details:
Experimental Method:
Resolution:
3.26 Å
R-Value Free:
0.25
R-Value Work:
0.21
R-Value Observed:
0.21
Space Group:
C 2 2 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Molecule:Enantio-pyochelin receptor
Gene (Uniprot):fetA
Chain IDs:A, B
Chain Length:748
Number of Molecules:2
Biological Source:Pseudomonas fluorescens
Primary Citation
Pyochelin enantiomers and their outer-membrane siderophore transporters in fluorescent pseudomonads: structural bases for unique enantiospecific recognition
J.Am.Chem.Soc. 133 16503 16509 (2011)
PMID: 21902256 DOI: 10.1021/ja205504z

Abstact

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.

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