This Article Full Text (PDF) Other Versions of this Article: JB.01093-07v1 190/1/421    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Brinkman, K. K. Articles by Larsen, R. A. Search for Related Content PubMed PubMed Citation Articles by Brinkman, K. K. Articles by Larsen, R. A.

 Previous Article  |  Next Article 

J. Bacteriol. doi:10.1128/JB.01093-07
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Interactions of the energy transducer TonB with non-cognate energy-harvesting complexes

Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403

^* To whom correspondence should be addressed. Email: larsera{at}bgnet.bgsu.edu.

	Abstract

The TonB and TolA proteins are energy transducers, coupling the ion electrochemical potential of the cytoplasmic membrane to support energy-dependent processes at the outer membrane of the gram-negative envelope. The transfer of energy to these transducers is facilitated by energy-harvesting complexes; heteromultimers of cytoplasmic membrane proteins with homologies to proton pump proteins of the flagellar motor. Although its cognate energy-harvesting complex best services each transducer, components of these complexes (for TonB: ExbB and ExbD; for TolA: TolQ and TolR) are sufficiently similar that each complex can imperfectly replace the other. Previous investigations of this molecular cross-talk have considered energy-harvesting complex components expressed from multi-copy plasmids in strains where the corresponding genes were interrupted by insertions, partially absent due to polarity, or missing due to a larger deletion. These questions are reexamined here in strains where individual genes have been removed by precise deletions and, where possible, components are expressed from single copy genes with native promoters. By more closely approximating natural stoichiometries between components, these studies provide insight to the roles of energy-harvesting complexes in both the energization and the stabilization of TonB. Further, these data suggest a distinct role for ExbD in the TonB energy transduction cycle.