Document Detail

Modeling the light- and redox-dependent interaction of PpsR/AppA in Rhodobacter sphaeroides.
MedLine Citation:
PMID:  21575568     Owner:  NLM     Status:  MEDLINE    
Facultative photosynthetic bacteria switch their energy generation mechanism from respiration to photosynthesis depending on oxygen tension and light. Part of this transition is mediated by the aerobic transcriptional repressor PpsR. In Rhodobacter sphaeroides, the repressive action of PpsR is antagonized by the redox- and blue-light-sensitive flavoprotein AppA which results in a unique phenotype: the repression of photosynthesis genes at intermediate oxygen levels and high light intensity, which is believed to reduce the risk of photooxidative stress. To analyze the underlying mechanism we developed a simple mathematical model based on the AppA-dependent reduction of a disulfide bond in PpsR and the light-sensitive complex formation between the reduced forms of AppA and PpsR. A steady-state analysis shows that high light repression can indeed occur at intermediate oxygen levels if PpsR is reduced on a faster timescale than AppA and if the electron transfer from AppA to PpsR is effectively irreversible. The model further predicts that if AppA copy numbers exceed those of PpsR by at least a factor of two, the transition from aerobic to anaerobic growth mode can occur via a bistable regime. We provide necessary conditions for the emergence of bistability and discuss possible experimental verifications.
Rakesh Pandey; Dietrich Flockerzi; Marcus J B Hauser; Ronny Straube
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biophysical journal     Volume:  100     ISSN:  1542-0086     ISO Abbreviation:  Biophys. J.     Publication Date:  2011 May 
Date Detail:
Created Date:  2011-05-17     Completed Date:  2011-09-05     Revised Date:  2013-06-28    
Medline Journal Info:
Nlm Unique ID:  0370626     Medline TA:  Biophys J     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2347-55     Citation Subset:  IM    
Copyright Information:
Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.
Systems Biology Group, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany.
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MeSH Terms
Aerobiosis / radiation effects
Bacterial Proteins / metabolism*
Flavoproteins / metabolism*
Genes, Bacterial / genetics
Models, Biological*
Oxidation-Reduction / radiation effects
Oxygen / metabolism
Photosynthesis / genetics,  radiation effects
Protein Binding / radiation effects
Rhodobacter sphaeroides / genetics,  metabolism*,  radiation effects*
Reg. No./Substance:
0/AppA protein, Rhodobacter sphaeroides; 0/Bacterial Proteins; 0/Flavoproteins; 7782-44-7/Oxygen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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