Document Detail


Thioredoxin m4 controls photosynthetic alternative electron pathways in Arabidopsis.
MedLine Citation:
PMID:  23151348     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In addition to the linear electron flow, a cyclic electron flow (CEF) around photosystem I occurs in chloroplasts. In CEF, electrons flow back from the donor site of photosystem I to the plastoquinone pool via two main routes: one that involves the Proton Gradient Regulation5 (PGR5)/PGRL1 complex (PGR) and one that is dependent of the NADH dehydrogenase-like complex. While the importance of CEF in photosynthesis and photoprotection has been clearly established, little is known about its regulation. We worked on the assumption of a redox regulation and surveyed the putative role of chloroplastic thioredoxins (TRX). Using Arabidopsis (Arabidopsis thaliana) mutants lacking different TRX isoforms, we demonstrated in vivo that TRXm4 specifically plays a role in the down-regulation of the NADH dehydrogenase-like complex-dependent plastoquinone reduction pathway. This result was confirmed in tobacco (Nicotiana tabacum) plants overexpressing the TRXm4 orthologous gene. In vitro assays performed with isolated chloroplasts and purified TRXm4 indicated that TRXm4 negatively controls the PGR pathway as well. The physiological significance of this regulation was investigated under steady-state photosynthesis and in the pgr5 mutant background. Lack of TRXm4 reversed the growth phenotype of the pgr5 mutant, but it did not compensate for the impaired photosynthesis and photoinhibition sensitivity. This suggests that the physiological role of TRXm4 occurs in vivo via a mechanism distinct from direct up-regulation of CEF.
Authors:
Agathe Courteille; Simona Vesa; Ruth Sanz-Barrio; Anne-Claire Cazalé; Noëlle Becuwe-Linka; Immaculada Farran; Michel Havaux; Pascal Rey; Dominique Rumeau
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-11-14
Journal Detail:
Title:  Plant physiology     Volume:  161     ISSN:  1532-2548     ISO Abbreviation:  Plant Physiol.     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2012-12-31     Completed Date:  2013-06-18     Revised Date:  2014-01-09    
Medline Journal Info:
Nlm Unique ID:  0401224     Medline TA:  Plant Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  508-20     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Arabidopsis / genetics,  metabolism*,  physiology,  radiation effects
Arabidopsis Proteins / metabolism
Chlorophyll / metabolism
Chloroplast Proteins / genetics,  metabolism
Chloroplasts / metabolism
Electron Transport
Enzyme Activation
Ethylmaleimide / pharmacology
Gene Expression Regulation, Enzymologic
Gene Expression Regulation, Plant
Genes, Plant
Light
Mutagenesis, Insertional
NADH Dehydrogenase / metabolism
Oxidation-Reduction
Photosynthesis*
Photosynthetic Reaction Center Complex Proteins / metabolism
Photosystem I Protein Complex / genetics,  metabolism*
Plant Leaves / genetics,  metabolism,  radiation effects
Plants, Genetically Modified / genetics,  metabolism,  radiation effects
Plastoquinone / metabolism
Recombinant Proteins / genetics,  metabolism
Thioredoxins / genetics,  metabolism*
Tobacco / genetics,  metabolism
Chemical
Reg. No./Substance:
0/Arabidopsis Proteins; 0/Chloroplast Proteins; 0/PGR5 protein, Arabidopsis; 0/Photosynthetic Reaction Center Complex Proteins; 0/Photosystem I Protein Complex; 0/Recombinant Proteins; 1406-65-1/Chlorophyll; 52500-60-4/Thioredoxins; EC 1.6.99.3/NADH Dehydrogenase; O3C74ACM9V/Ethylmaleimide; OAC30J69CN/Plastoquinone
Comments/Corrections

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