This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Held, K. G.
Right arrow Articles by Postle, K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Held, K. G.
Right arrow Articles by Postle, K.

 Previous Article  |  Next Article 

Journal of Bacteriology, September 2002, p. 5170-5173, Vol. 184, No. 18
0021-9193/02/$04.00+0     DOI: 10.1128/JB.184.18.5170-5173.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.

ExbB and ExbD Do Not Function Independently in TonB-Dependent Energy Transduction

Kiara G. Held,{dagger} and Kathleen Postle*

School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-4233

Received 20 May 2002/ Accepted 18 June 2002

ExbB and ExbD proteins are part of the TonB-dependent energy transduction system and are encoded by the exb operon in Escherichia coli. TonB, the energy transducer, appears to go through a cycle during energy transduction, with the absence of both ExbB and ExbD creating blocks at two points: (i) in the inability of TonB to respond to the cytoplasmic membrane proton motive force and (ii) in the conversion of TonB from a high-affinity outer membrane association to a high-affinity cytoplasmic membrane association. The recent observation that ExbB exists in 3.5-fold molar excess relative to the molarity of ExbD in E. coli suggests the possibility of two types of complexes, those containing both ExbB and ExbD and those containing only ExbB. Such distinct complexes might individually manifest one of the two activities described above. In the present study this hypothesis was tested and rejected. Specifically, both ExbB and ExbD were found to be required for TonB to conformationally respond to proton motive force. Both ExbB and ExbD were also required for association of TonB with the cytoplasmic membrane. Together, these results support an alternative model where all of the ExbB in the cell occurs in complex with all of the ExbD in the cell. Based on recently determined cellular ratios of TonB system proteins, these results suggest the existence of a cytoplasmic membrane complex that may be as large as 520 kDa.

* Corresponding author. Mailing address: School of Molecular Biosciences, Washington State University, Pullman, WA 99164-4233. Phone: (509) 335-5614. Fax: (509) 335-1907. E-mail: postle{at}wsu.edu.

{dagger} Present address: Pacific Northwest Research Institute, Seattle, WA 98122.

Journal of Bacteriology, September 2002, p. 5170-5173, Vol. 184, No. 18
0021-9193/02/$04.00+0     DOI: 10.1128/JB.184.18.5170-5173.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Brinkman, K. K., Larsen, R. A. (2008). Interactions of the Energy Transducer TonB with Noncognate Energy-Harvesting Complexes. J. Bacteriol. 190: 421-427 [Abstract] [Full Text]  
  • Vakharia-Rao, H., Kastead, K. A., Savenkova, M. I., Bulathsinghala, C. M., Postle, K. (2007). Deletion and Substitution Analysis of the Escherichia coli TonB Q160 Region. J. Bacteriol. 189: 4662-4670 [Abstract] [Full Text]  
  • Sigdel, T. K., Easton, J. A., Crowder, M. W. (2006). Transcriptional Response of Escherichia coli to TPEN.. J. Bacteriol. 188: 6709-6713 [Abstract] [Full Text]  
  • Stork, M., Di Lorenzo, M., Mourino, S., Osorio, C. R., Lemos, M. L., Crosa, J. H. (2004). Two tonB Systems Function in Iron Transport in Vibrio anguillarum, but Only One Is Essential for Virulence. Infect. Immun. 72: 7326-7329 [Abstract] [Full Text]  
  • Larsen, R. A., Chen, G. J., Postle, K. (2003). Performance of Standard Phenotypic Assays for TonB Activity, as Evaluated by Varying the Level of Functional, Wild-Type TonB. J. Bacteriol. 185: 4699-4706 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»