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 Dasgupta, N.
Right arrow Articles by Yahr, T. L.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Dasgupta, N.
Right arrow Articles by Yahr, T. L.

 Previous Article  |  Next Article 

Infection and Immunity, June 2006, p. 3334-3341, Vol. 74, No. 6
0019-9567/06/$08.00+0     doi:10.1128/IAI.00090-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Transcriptional Induction of the Pseudomonas aeruginosa Type III Secretion System by Low Ca2+ and Host Cell Contact Proceeds through Two Distinct Signaling Pathways

Nandini Dasgupta,1 Alix Ashare,2 Gary W. Hunninghake,2,3 and Timothy L. Yahr1*

Departments of Microbiology,1 Internal Medicine, University of Iowa, Iowa City, Iowa 52242,2 the Veterans' Administration Medical Center, Iowa City, Iowa3

Received 17 January 2006/ Returned for modification 8 February 2006/ Accepted 1 April 2006

The opportunistic pathogen Pseudomonas aeruginosa utilizes a type III secretion system (T3SS) to intoxicate eukaryotic host cells. Transcription of the T3SS is induced under calcium-limited growth conditions or following intimate contact of P. aeruginosa with host cells. In the present study, we demonstrate that expression of the T3SS is controlled by two distinct regulatory mechanisms and that these mechanisms are differentially activated in a host cell-dependent manner. The first mechanism is dependent upon ExsC, a regulatory protein that couples transcription of the T3SS to the activity of the type III secretion machinery. ExsC is essential for induction of the T3SS under low-calcium-growth conditions and for T3SS-dependent cytotoxicity towards social amoebae, insect cells, and erythrocytes. The second regulatory mechanism functions independently of ExsC and is sufficient to elicit T3SS-dependent cytotoxicity towards certain types of mammalian cells. Although this second pathway (ExsC independent) is sufficient, an exsC mutant demonstrates a lag in the induction of cytotoxicity towards Chinese hamster ovary cells and is attenuated for virulence in a mouse pneumonia model. We propose that the ExsC-dependent pathway is required for full cytotoxicity towards all host cell types tested whereas the ExsC-independent pathway may represent an adaptation that allows P. aeruginosa to increase expression of the T3SS in response to specific types of mammalian cells.

* Corresponding author. Mailing address: Department of Microbiology, 540B Eckstein Medical Research Building, University of Iowa, Iowa City, IA 52242-1101. Phone: (319) 335-9688. Fax: (319) 335-8228. E-mail: timothy-yahr{at}uiowa.edu.

Editor: J. T. Barbieri

Infection and Immunity, June 2006, p. 3334-3341, Vol. 74, No. 6
0019-9567/06/$08.00+0     doi:10.1128/IAI.00090-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Mikkelsen, H., Bond, N. J., Skindersoe, M. E., Givskov, M., Lilley, K. S., Welch, M. (2009). Biofilms and type III secretion are not mutually exclusive in Pseudomonas aeruginosa. Microbiology 155: 687-698 [Abstract] [Full Text]  
  • Angus, A. A., Lee, A. A., Augustin, D. K., Lee, E. J., Evans, D. J., Fleiszig, S. M. J. (2008). Pseudomonas aeruginosa Induces Membrane Blebs in Epithelial Cells, Which Are Utilized as a Niche for Intracellular Replication and Motility. Infect. Immun. 76: 1992-2001 [Abstract] [Full Text]  
  • Urbanowski, M. L., Brutinel, E. D., Yahr, T. L. (2007). Translocation of ExsE into Chinese Hamster Ovary Cells Is Required for Transcriptional Induction of the Pseudomonas aeruginosa Type III Secretion System. Infect. Immun. 75: 4432-4439 [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»