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 Luo, Z.-Q.
Right arrow Articles by Farrand, S. K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Luo, Z.-Q.
Right arrow Articles by Farrand, S. K.

 Previous Article  |  Next Article 

Journal of Bacteriology, October 2003, p. 5665-5672, Vol. 185, No. 19
0021-9193/03/$08.00+0     DOI: 10.1128/JB.185.19.5665-5672.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.

In Situ Activation of the Quorum-Sensing Transcription Factor TraR by Cognate and Noncognate Acyl-Homoserine Lactone Ligands: Kinetics and Consequences

Zhao-Qing Luo,1,{dagger} Shengchang Su,1 and Stephen K. Farrand1,2*

Departments of Crop Sciences,1 Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois 618012

Received 13 January 2003/ Accepted 16 July 2003

Conjugal transfer of Ti plasmids of Agrobacterium tumefaciens is controlled by a quorum-sensing system composed of the transcriptional activator TraR and its acyl-homoserine lactone quormone N-(3-oxo-octanoyl)-L-homoserine lactone (3-oxo-C8-HSL). The population density dependence of quorum-sensing systems can often be circumvented by addition of the quormone to cultures at low cell numbers. However, the quorum-dependent activation of Ti plasmid conjugal transfer exhibited a lag of almost 8 h when the quormone was added to donor cells at low population densities (Piper and Farrand, J. Bacteriol. 182:1080-1088, 2000). As measured by activation of a TraR-dependent traG::lacZ reporter fusion, TraR in cells exposed to the cognate signal for 5 min showed detectable activity, while exposure for 15 min resulted in full activity. Thus, the lag in activation is not due to some intrinsic property of TraR. Cells exposed to the agonistic analog N-(3-oxo-hexanoyl)-L-homoserine lactone (3-oxo-C6-HSL) exhibited similar induction kinetics. However, activation of the reporter in cells exposed to the poorly effective alkanoyl acyl-HSL N-hexanoyl-L-homoserine lactone (C6-HSL) required the continued presence of the signal. As measured by an in vivo repressor assay, TraR activated by 3-oxo-C6-HSL or by 3-oxo-C8-HSL remained active for as long as 8 h after removal of exogenous signal. However, TraR activated by the alkanoyl quormone C6-HSL rapidly lost activity following removal of the signal. In quormone retention assays, which measure signal binding by TraR, cells grown with either of the two 3-oxo-acyl-HSL quormones retained the ligand after washing, while cells grown with C6-HSL lost the alkanoyl-HSL concomitant with the rapid loss of TraR activity. We conclude that TraR rapidly binds its quormone and that, once bound, the cognate signal and its close homologs are tightly retained. Moreover, in the absence of other regulatory factors, activated TraR remains functional after removal of the signal. On the other hand, poorly active signals are not tightly bound, and their removal by washing leads to rapid loss of TraR activity.

* Corresponding author. Mailing address: Department of Crop Sciences, University of Illinois at Urbana-Champaign, 240 ERML, 1201 West Gregory Drive, Urbana, IL 61801. Phone: (217) 333-1524. Fax: (217) 244-7830. E-mail: stephenf{at}uiuc.edu.

{dagger} Present address: Department of Microbiology and Molecular Biology, Tufts University School of Medicine, Boston, MA 02148.

Journal of Bacteriology, October 2003, p. 5665-5672, Vol. 185, No. 19
0021-9193/03/$08.00+0     DOI: 10.1128/JB.185.19.5665-5672.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Khan, S. R., Farrand, S. K. (2009). The BlcC (AttM) Lactonase of Agrobacterium tumefaciens Does Not Quench the Quorum-Sensing System That Regulates Ti Plasmid Conjugative Transfer. J. Bacteriol. 191: 1320-1329 [Abstract] [Full Text]  
  • Iida, A., Ohnishi, Y., Horinouchi, S. (2008). An OmpA Family Protein, a Target of the GinI/GinR Quorum-Sensing System in Gluconacetobacter intermedius, Controls Acetic Acid Fermentation. J. Bacteriol. 190: 5009-5019 [Abstract] [Full Text]  
  • Su, S., Khan, S. R., Farrand, S. K. (2008). Induction and Loss of Ti Plasmid Conjugative Competence in Response to the Acyl-Homoserine Lactone Quorum-Sensing Signal. J. Bacteriol. 190: 4398-4407 [Abstract] [Full Text]  
  • Kawaguchi, T., Chen, Y. P., Norman, R. S., Decho, A. W. (2008). Rapid Screening of Quorum-Sensing Signal N-Acyl Homoserine Lactones by an In Vitro Cell-Free Assay. Appl. Environ. Microbiol. 74: 3667-3671 [Abstract] [Full Text]  
  • Iida, A., Ohnishi, Y., Horinouchi, S. (2008). Control of Acetic Acid Fermentation by Quorum Sensing via N-Acylhomoserine Lactones in Gluconacetobacter intermedius. J. Bacteriol. 190: 2546-2555 [Abstract] [Full Text]  
  • Uroz, S., Oger, P. M., Chapelle, E., Adeline, M.-T., Faure, D., Dessaux, Y. (2008). A Rhodococcus qsdA-Encoded Enzyme Defines a Novel Class of Large-Spectrum Quorum-Quenching Lactonases. Appl. Environ. Microbiol. 74: 1357-1366 [Abstract] [Full Text]  
  • Wilhelm, S., Gdynia, A., Tielen, P., Rosenau, F., Jaeger, K.-E. (2007). The Autotransporter Esterase EstA of Pseudomonas aeruginosa Is Required for Rhamnolipid Production, Cell Motility, and Biofilm Formation. J. Bacteriol. 189: 6695-6703 [Abstract] [Full Text]  
  • Lujan, A. M., Moyano, A. J., Segura, I., Argarana, C. E., Smania, A. M. (2007). Quorum-sensing-deficient (lasR) mutants emerge at high frequency from a Pseudomonas aeruginosa mutS strain. Microbiology 153: 225-237 [Abstract] [Full Text]  
  • Janssens, J. C. A., Metzger, K., Daniels, R., Ptacek, D., Verhoeven, T., Habel, L. W., Vanderleyden, J., De Vos, D. E., De Keersmaecker, S. C. J. (2007). Synthesis of N-Acyl Homoserine Lactone Analogues Reveals Strong Activators of SdiA, the Salmonella enterica Serovar Typhimurium LuxR Homologue. Appl. Environ. Microbiol. 73: 535-544 [Abstract] [Full Text]  
  • You, Y.-S., Marella, H., Zentella, R., Zhou, Y., Ulmasov, T., Ho, T.-H. D., Quatrano, R. S. (2006). Use of bacterial quorum-sensing components to regulate gene expression in plants.. Plant Physiol. 140: 1205-1212 [Abstract] [Full Text]  
  • Koch, B., Liljefors, T., Persson, T., Nielsen, J., Kjelleberg, S., Givskov, M. (2005). The LuxR receptor: the sites of interaction with quorum-sensing signals and inhibitors. Microbiology 151: 3589-3602 [Abstract] [Full Text]  
  • Molina, L., Rezzonico, F., Defago, G., Duffy, B. (2005). Autoinduction in Erwinia amylovora: Evidence of an Acyl-Homoserine Lactone Signal in the Fire Blight Pathogen. J. Bacteriol. 187: 3206-3213 [Abstract] [Full Text]  
  • Vannini, A., Volpari, C., Di Marco, S. (2004). Crystal Structure of the Quorum-sensing Protein TraM and Its Interaction with the Transcriptional Regulator TraR. J. Biol. Chem. 279: 24291-24296 [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»