Document Detail

The role of PGR5 in the redox poising of photosynthetic electron transport.
MedLine Citation:
PMID:  17803955     Owner:  NLM     Status:  MEDLINE    
The pgr5 mutant of Arabidopsis thaliana has been described as being deficient in cyclic electron flow around photosystem I, however, the precise role of the PGR5 protein remains unknown. To address this issue, photosynthetic electron transport was examined in intact leaves of pgr5 and wild type A. thaliana. Based on measurements of the kinetics of P700 oxidation in far red light and re-reduction following oxidation in the presence of DCMU, we conclude that this mutant is able to perform cyclic electron flow at a rate similar to the wild type. The PGR5 protein is therefore not essential for cyclic flow. However, cyclic flow is affected by the pgr5 mutation under conditions where this process is normally enhanced in wild type leaves, i.e. high light or low CO(2) concentrations resulted in enhancement of cyclic electron flow. This suggests a different capacity to regulate cyclic flow in response to environmental stimuli in the mutant. We also show that the pgr5 mutant is affected in the redox poising of the chloroplast, with the electron transport chain being substantially reduced under most conditions. This may result in defective feedback regulation of photosynthetic electron transport under some conditions, thus providing a rationale for the reduced efficiency of cyclic electron flow.
Beena Nandha; Giovanni Finazzi; Pierre Joliot; Simon Hald; Giles N Johnson
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Publication Detail:
Type:  Journal Article     Date:  2007-08-03
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  1767     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  2007 Oct 
Date Detail:
Created Date:  2007-10-08     Completed Date:  2007-11-21     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  1252-9     Citation Subset:  IM    
Faculty of Life Sciences, University of Manchester, 3.614 Stopford Building Oxford Road, Manchester, UK.
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MeSH Terms
Arabidopsis / drug effects,  genetics,  metabolism
Arabidopsis Proteins / genetics,  metabolism*
Carbon Dioxide / pharmacology
Chlorophyll / metabolism
Diuron / pharmacology
Electron Transport
Gene Expression Regulation, Plant
Mutation / genetics
Photosynthetic Reaction Center Complex Proteins / genetics,  metabolism*
Plants, Genetically Modified
Sensitivity and Specificity
Stromal Cells / metabolism
Reg. No./Substance:
0/Arabidopsis Proteins; 0/PGR5 protein, Arabidopsis; 0/Photosynthetic Reaction Center Complex Proteins; 124-38-9/Carbon Dioxide; 1406-65-1/Chlorophyll; 330-54-1/Diuron

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