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 Zhao, Q.
Right arrow Articles by Poole, K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Zhao, Q.
Right arrow Articles by Poole, K.
Right arrowPubmed/NCBI databases
*Compound via MeSH
*Substance via MeSH
Hazardous Substances DB
*IRON

Next Article 

Journal of Bacteriology, March 2002, p. 1503-1513, Vol. 184, No. 6
0021-9193/02/$04.00+0     DOI: 10.1128/JB.184.6.1503-1513.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.

Mutational Analysis of the TonB1 Energy Coupler of Pseudomonas aeruginosa

Qixun Zhao and Keith Poole*

Department of Microbiology and Immunology, Queen's University, Kingston, Ontario K7L 3N6, Canada

Received 10 October 2001/ Accepted 10 December 2001

Siderophore-mediated iron transport in Pseudomonas aeruginosa is dependent upon the cytoplasmic membrane-associated TonB1 energy coupling protein for activity. To assess the functional significance of the various regions of this molecule and to identify functionally important residues, the tonB1 gene was subjected to site-directed mutagenesis, and the influence on iron acquisition was determined. The novel N-terminal extension of TonB1, which is absent in all other examples of TonB, was required for TonB1 activity in both P. aeruginosa and Escherichia coli. Appending it to the N terminus of the nonfunctional (in P. aeruginosa) Escherichia coli TonB protein (TonBEc) rendered TonBEc weakly active in P. aeruginosa and did not compromise the activity of this protein in E. coli. Elimination of the membrane-spanning, presumed membrane anchor sequence of TonB1 abrogated TonB1 activity in P. aeruginosa and E. coli. Interestingly, however, a conserved His residue within the membrane anchor sequence, shown to be required for TonBEc function in E. coli, was shown here to be essential for TonB1 activity in E. coli but not in P. aeruginosa. Several mutations within the C-terminal end of TonB1, within a region exhibiting the greatest similarity to other TonB proteins, compromised a TonB1 contribution to iron acquisition in both P. aeruginosa and E. coli, including substitutions at Tyr264, Glu274, Lys278, and Asp304. Mutations at Pro265, Gln293, and Val294 also impacted negatively on TonB1 function in E. coli but not in P. aeruginosa. The Asp304 mutation was suppressed by a second mutation at Glu274 of TonB1 but only in P. aeruginosa. Several TonB1-TonBEc chimeras were constructed, and assessment of their activities revealed that substitutions at the N or C terminus of TonB1 compromised its activity in P. aeruginosa, although chimeras possessing an E. coli C terminus were active in E. coli.

* Corresponding author. Mailing address: Department of Microbiology and Immunology, Queen's University, Kingston, Ontario K7L 3N6, Canada. Phone: (613) 533-6677. Fax: (613) 533-6796. E-mail: poolek{at}post.queensu.ca.

Journal of Bacteriology, March 2002, p. 1503-1513, Vol. 184, No. 6
0021-9193/02/$04.00+0     DOI: 10.1128/JB.184.6.1503-1513.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • 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]  
  • Adams, H., Zeder-Lutz, G., Schalk, I., Pattus, F., Celia, H. (2006). Interaction of TonB with the Outer Membrane Receptor FpvA of Pseudomonas aeruginosa.. J. Bacteriol. 188: 5752-5761 [Abstract] [Full Text]  
  • Cuiv, P. O, Clarke, P., O'Connell, M. (2006). Identification and characterization of an iron-regulated gene, chtA, required for the utilization of the xenosiderophores aerobactin, rhizobactin 1021 and schizokinen by Pseudomonas aeruginosa.. Microbiology 152: 945-954 [Abstract] [Full Text]  
  • Neugebauer, H., Herrmann, C., Kammer, W., Schwarz, G., Nordheim, A., Braun, V. (2005). ExbBD-Dependent Transport of Maltodextrins through the Novel MalA Protein across the Outer Membrane of Caulobacter crescentus. J. Bacteriol. 187: 8300-8311 [Abstract] [Full Text]  
  • Huang, B., Ru, K., Yuan, Z., Whitchurch, C. B., Mattick, J. S. (2004). tonB3 Is Required for Normal Twitching Motility and Extracellular Assembly of Type IV Pili. J. Bacteriol. 186: 4387-4389 [Abstract] [Full Text]  
  • Mey, A. R., Payne, S. M. (2003). Analysis of Residues Determining Specificity of Vibrio cholerae TonB1 for Its Receptors. J. Bacteriol. 185: 1195-1207 [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»