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Applied and Environmental Microbiology, May 2009, p. 2775-2783, Vol. 75, No. 9
0099-2240/09/$08.00+0 doi:10.1128/AEM.02897-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
FvtA Is the Receptor for the Siderophore Vanchrobactin in Vibrio anguillarum: Utility as a Route of Entry for Vanchrobactin Analogues 
,
Miguel Balado,
Carlos R. Osorio, and
Manuel L. Lemos*
Department of Microbiology and Parasitology, Institute of Aquaculture and Faculty of Biology, University of Santiago de Compostela, Campus Sur, 15782 Santiago de Compostela, Spain
Received 19 December 2008/ Accepted 1 March 2009
Some strains of Vibrio anguillarum, the causative agent of vibriosis in a variety of marine animals, produce a catechol-type siderophore named vanchrobactin. The biosynthetic pathway and regulation of vanchrobactin are quite well understood. However, aspects concerning its entry into the cell have remained uncharacterized. In the present study we characterized two genes, fvtA and orf13, encoding potential TonB-dependent ferric-vanchrobactin receptors in serotype O2 V. anguillarum strain RV22. We found that an fvtA mutant was defective for growth under iron limitation conditions and for utilization of vanchrobactin, suggesting that fvtA encodes the vanchrobactin receptor of V. anguillarum. Interestingly, an orf13 mutant was not significantly affected, and results of reverse transcriptase PCR, as well as analysis of outer membrane proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, suggested that this gene is not expressed. Furthermore, fatA, a plasmid gene coding for the anguibactin receptor in plasmid pJM1-harboring strains, is also present in the chromosome of RV22, although it is inactivated by insertion of transposases. In addition, we found that FvtA is the route of entry for vanchrobactin analogues, and there is evidence that it recognizes primarily the catechol-iron center. These analogues are potential candidate vectors for a Trojan horse strategy aimed at generating antimicrobial compounds exploiting the same route of entry for native siderophores. We found that fvtA and vanchrobactin biosynthesis genes are ubiquitous in both vanchrobactin- and anguibactin-producing V. anguillarum strains, which reinforces the utility of the vanchrobactin route of entry for the design of future strategies for the control of vibriosis.
* Corresponding author. Mailing address: Department of Microbiology and Parasitology, Institute of Aquaculture, University of Santiago de Compostela, Campus Sur, 15782 Santiago de Compostela, Spain. Phone: 34-981563100, ext. 16080. Fax: 34-981547165. E-mail: manuel.lemos{at}usc.es
Published ahead of print on 6 March 2009.
Supplemental material for this article may be found at http://aem.asm.org/.
Applied and Environmental Microbiology, May 2009, p. 2775-2783, Vol. 75, No. 9
0099-2240/09/$08.00+0 doi:10.1128/AEM.02897-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
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