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Journal of Bacteriology, September 2009, p. 5634-5640, Vol. 191, No. 18
0021-9193/09/$08.00+0     doi:10.1128/JB.00742-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Role of TonB1 in Pyoverdine-Mediated Signaling in Pseudomonas aeruginosa{triangledown}

Matt Shirley and Iain L. Lamont*

Department of Biochemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand

Received 8 June 2009/ Accepted 2 July 2009

Pyoverdines are siderophores secreted by Pseudomonas aeruginosa. Uptake of ferripyoverdine in P. aeruginosa PAO1 occurs via the FpvA receptor protein and requires the energy-transducing protein TonB1. Interaction of (ferri)pyoverdine with FpvA activates pyoverdine gene expression in a signaling process involving the cytoplasmic-membrane-spanning anti-sigma factor FpvR and the sigma factor PvdS. Here, we show that mutation of a region of FpvA that interacts with TonB1 (the TonB box) prevents this signaling process, as well as inhibiting bacterial growth in the presence of the iron-chelating compound ethylenediamine-di(o-hydroxy-phenylacetic acid). Signaling via wild-type FpvA was also eliminated in strains lacking TonB1 but was unaffected in strains lacking either (or both) of two other TonB proteins in P. aeruginosa, TonB2 and TonB3. An absence of pyoverdine-mediated signaling corresponded with proteolysis of PvdS. These data show that interactions between FpvA and TonB1 are required for (ferri)pyoverdine signal transduction, as well as for ferripyoverdine transport, consistent with a mechanistic link between the signaling and transport functions of FpvA.

* Corresponding author. Mailing address: Department of Biochemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand. Phone: (64) 3 479 7869. Fax: (64) 3 479 7866. E-mail: iain.lamont{at}otago.ac.nz

{triangledown} Published ahead of print on 10 July 2009.

Journal of Bacteriology, September 2009, p. 5634-5640, Vol. 191, No. 18
0021-9193/09/$08.00+0     doi:10.1128/JB.00742-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





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