Stereospecificity of the Siderophore Pyochelin Outer Membrane Transporters in Fluorescent Pseudomonads*
AUTOR(ES)
Hoegy, Françoise
FONTE
American Society for Biochemistry and Molecular Biology
RESUMO
Pyochelin (Pch) and enantio-pyochelin (EPch) are enantiomer siderophores that are produced by Pseudomonas aeruginosa and Pseudomonas fluorescens, respectively, under iron limitation. Pch promotes growth of P. aeruginosa when iron is scarce, and EPch carries out the same biological function in P. fluorescens. However, the two siderophores are unable to promote growth in the heterologous species, indicating that siderophore-mediated iron uptake is highly stereospecific. In the present work, using binding and iron uptake assays, we found that FptA, the Fe-Pch outer membrane transporter of P. aeruginosa, recognized (Kd = 2.5 ± 1.1 nm) and transported Fe-Pch but did not interact with Fe-EPch. Likewise, FetA, the Fe-EPch receptor of P. fluorescens, was specific for Fe-EPch (Kd = 3.7 ± 2.1 nm) but did not bind and transport Fe-Pch. Growth promotion experiments performed under iron-limiting conditions confirmed that FptA and FetA are highly specific for Pch and EPch, respectively. When fptA and fetA along with adjacent transport genes involved in siderophore uptake were swapped between the two bacterial species, P. aeruginosa became able to utilize Fe-EPch as an iron source, and P. fluorescens was able to grow with Fe-Pch. Docking experiments using the FptA structure and binding assays showed that the stereospecificity of Pch recognition by FptA was mostly due to the configuration of the siderophore chiral centers C4″ and C2″ and was only weakly dependent on the configuration of the C4′ carbon atom. Together, these findings increase our understanding of the stereospecific interaction between Pch and its outer membrane receptor FptA.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2685677Documentos Relacionados
- Siderophore Typing, a Powerful Tool for the Identification of Fluorescent and Nonfluorescent Pseudomonads
- Outer membrane protein mediating iron uptake via pyoverdinpss, the fluorescent siderophore produced by Pseudomonas syringae pv. syringae.
- Cloning of the outer membrane high-affinity Fe(III)-pyochelin receptor of Pseudomonas aeruginosa.
- Demonstration of an iron-siderophore-binding protein in the outer membrane of Pseudomonas aeruginosa.
- Secondary metabolites of the fluorescent pseudomonads.