NADPH Thioredoxin reductase C controls the redox status of chloroplast 2-Cys peroxiredoxins in Arabidopsis thaliana.
Chloroplast 2-Cys peroxiredoxins (2-Cys Prxs) are efficiently reduced by NADPH Thioredoxin reductase C (NTRC). To investigate the effect of light/darkness on NTRC function, the content of abundant plastidial enzymes, Rubisco, glutamine synthetase (GS), and 2-Cys Prxs was analyzed during two consecutive days in Arabidopsis wild-type and ntrc mutant plants. No significant difference of the content of these proteins was observed during the day or the night in wild-type and mutant plants. NTRC deficiency caused a lower content of fully reduced 2-Cys Prxs, which was undetectable in darkness, suggesting that NTRC is the most important pathway for 2-Cys Prx reduction, probably the only one during the night. Arabidopsis contains two plastidial 2-Cys Prxs, A and B, for which T-DNA insertion lines were characterized showing the same phenotype as wild-type plants. Two-dimensional gel analysis of leaf extracts from these mutants allowed the identification of basic and acidic isoforms of 2-Cys Prx A and B. In-vitro assays and mass spectrometry analysis showed that the acidic isoform of both proteins is produced by overoxidation of the peroxidatic Cys residue to sulfinic acid. 2-Cys Prx overoxidation was lower in the NTRC mutant. These results show the important function of NTRC to maintain the redox equilibrium of chloroplast 2-Cys Prxs.
Kirchsteiger
Kerstin
K
Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla and CSIC, Avda Américo Vespucio 49, 41092-Sevilla, Spain.
Pulido
Pablo
P
González
Maricruz
M
Cejudo
Francisco Javier
FJ
D017360:Arabidopsis / Q000201:enzymology / Q000378:metabolism*; D001483:Base Sequence; D015153:Blotting, Western; D002736:Chloroplasts / Q000378:metabolism*; D017931:DNA Primers; D010084:Oxidation-Reduction; D054464:Peroxiredoxins / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013880:Thioredoxin-Disulfide Reductase / Q000378:metabolism*
D017931:DNA Primers; D054464:Peroxiredoxins; D013880:Thioredoxin-Disulfide Reductase