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  An extended model for the repression of photosynthesis genes by the AppA/PpsR system in Rhodobacter sphaeroides

Pandey, R., Flockerzi, D., Hauser, M. J. B., & Straube, R. (2012). An extended model for the repression of photosynthesis genes by the AppA/PpsR system in Rhodobacter sphaeroides. FEBS Journal, 279(18), 3449-3461. doi:10.1111/j.1742-4658.2012.08520.X.

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Item Permalink: http://hdl.handle.net/11858/00-001M-0000-0013-89DD-F Version Permalink: http://hdl.handle.net/11858/00-001M-0000-0013-F47C-0
Genre: Journal Article

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 Creators:
Pandey, Rakesh1, 2, Author              
Flockerzi, Dietrich3, Author              
Hauser, Marcus J. B.4, Author
Straube, Ronny2, Author              
Affiliations:
1International Max Planck Research School (IMPRS), ou_1738143              
2Analysis and Redesign of Biological Networks, Max Planck Institute for Dynamics of Complex Technical Systems, Max Planck Society, ou_1738139              
3Systems and Control Theory, Max Planck Institute for Dynamics of Complex Technical Systems, Max Planck Society, ou_1738154              
4Otto-von-Guericke University,Biophysics Group, Institute of Experimental Physics,Magdeburg, Germany, ou_persistent22              

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 Abstract: Purple bacteria derive energy from aerobic respiration or photosynthesis depending on the availability of oxygen and light. Under aerobic conditions, photosynthesis genes are specifically repressed by the PpsR protein. In Rhodobacter sphaeroides, the repressive action of PpsR is antagonized by the blue-light and redox-sensitive flavoprotein AppA, which sequesters PpsR under anaerobic conditions into transcriptionally inactive complexes. However, under semi-aerobic conditions, blue-light excitation of AppA causes the AppA–PpsR complexes to dissociate, again leading to a repression of photosynthesis genes. We have recently developed a simple mathematical model suggesting that this phenotype arises from the formation of a maximum in the response curve of reduced PpsR at intermediate oxygen concentrations. However, this model focused mainly on the oxygen-dependent interactions whereas light regulation was only implemented in a simplified manner. In the present study, we incorporate a more detailed mechanism for the light-dependent interaction between AppA and PpsR, which now allows for a direct comparison with experiments. Specifically, we take into account that, upon blue–light excitation, AppA undergoes a conformational change, creating a long-lived signalling state causing the dissociation of the AppA–PpsR complexes. The predictions of the extended model are found to be in good agreement with experimental results on the light-dependent repression of photosynthesis genes under semi-aerobic conditions. We also identify the potential kinetic and stoichiometric constraints that the interplay between light and redox regulation imposes on the functionality of the AppA/PpsR system, especially with respect to a possible bistable response. Copyright © 1999–2013 John Wiley & Sons, Inc. All Rights Reserved. [accessed 2013 July 2nd]

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 Dates: 2012
 Publication Status: Published in print
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 Rev. Method: Internal
 Identifiers: eDoc: 609258
DOI: 10.1111/j.1742-4658.2012.08520.X
Other: 14/12
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Title: FEBS Journal
Source Genre: Journal
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Pages: - Volume / Issue: 279 (18) Sequence Number: - Start / End Page: 3449 - 3461 Identifier: -