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Journal of Bacteriology, March 2007, p. 2274-2282, Vol. 189, No. 6
0021-9193/07/$08.00+0     doi:10.1128/JB.01699-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

The AppA and PpsR Proteins from Rhodobacter sphaeroides Can Establish a Redox-Dependent Signal Chain but Fail To Transmit Blue-Light Signals in Other Bacteria{triangledown}

Andreas Jäger,3 Stephan Braatsch,1 Kerstin Haberzettl,3 Sebastian Metz,3 Lisa Osterloh,2 Yuchen Han,3 and Gabriele Klug3*

Institut für Mikrobiologie und Molekularbiologie, University of Giessen, Heinrich-Buff-Ring 26-32, D-35392 Giessen, Germany,3 Department of Microbiology and Immunology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada,1 Institut für Molekularbiologie und Tumorforschung, Philipps-Universität Marburg, Emil-Mannkopff-Str. 2, D-35037 Marburg, Germany2

Received 3 November 2006/ Accepted 21 December 2006

The AppA protein of Rhodobacter sphaeroides has the unique ability to sense and transmit redox and light signals. In response to decreasing oxygen tension, AppA antagonizes the transcriptional regulator PpsR, which represses the expression of photosynthesis genes, including the puc operon. This mechanism, which is based on direct protein-protein interaction, is prevented by blue-light absorption of the BLUF domain located in the N-terminal part of AppA. In order to test whether AppA and PpsR are sufficient to transmit redox and light signals, we expressed these proteins in three different bacterial species and monitored oxygen- and blue-light-dependent puc expression either directly or by using a luciferase-based reporter construct. The AppA/PpsR system could mediate redox-dependent gene expression in the alphaproteobacteria Rhodobacter capsulatus and Paracoccus denitrificans but not in the gammaproteobacterium Escherichia coli. Analysis of a prrA mutant strain of R. sphaeroides strongly suggests that light-dependent gene expression requires a balanced interplay of the AppA/PpsR system with the PrrA response regulator. Therefore, the AppA/PpsR system was unable to establish light signaling in other bacteria. Based on our data, we present a model for the interdependence of AppA/PpsR signaling and the PrrA transcriptional activator.

* Corresponding author. Mailing address: Institut für Mikrobiologie und Molekularbiologie, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany. Phone: (49) 641 99 355 42. Fax: (49) 641 99 355 49. E-mail: Gabriele.Klug{at}mikro.bio.uni-giessen.de.

{triangledown} Published ahead of print on 5 January 2007.

Journal of Bacteriology, March 2007, p. 2274-2282, Vol. 189, No. 6
0021-9193/07/$08.00+0     doi:10.1128/JB.01699-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Metz, S., Jager, A., Klug, G. (2009). In Vivo Sensitivity of Blue-Light-Dependent Signaling Mediated by AppA/PpsR or PrrB/PrrA in Rhodobacter sphaeroides. J. Bacteriol. 191: 4473-4477 [Abstract] [Full Text]  
  • Gomelsky, L., Moskvin, O. V., Stenzel, R. A., Jones, D. F., Donohue, T. J., Gomelsky, M. (2008). Hierarchical Regulation of Photosynthesis Gene Expression by the Oxygen-Responsive PrrBA and AppA-PpsR Systems of Rhodobacter sphaeroides. J. Bacteriol. 190: 8106-8114 [Abstract] [Full Text]  
  • Belas, R., Zhulin, I. B., Yang, Z. (2008). Bacterial Signaling and Motility: Sure Bets. J. Bacteriol. 190: 1849-1856 [Full Text]  
  • Arai, H., Roh, J. H., Kaplan, S. (2008). Transcriptome Dynamics during the Transition from Anaerobic Photosynthesis to Aerobic Respiration in Rhodobacter sphaeroides 2.4.1. J. Bacteriol. 190: 286-299 [Abstract] [Full Text]  


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