Thiol-based redox regulation is considered to support light-responsive control of various chloroplast functions. The redox cascade via ferredoxin–thioredoxin reductase (FTR)/thioredoxin (Trx) has been recognized as a key to transmitting reducing power; however, Arabidopsis thaliana genome sequencing has revealed that as many as five Trx subtypes encoded by a total of 10 nuclear genes are targeted to chloroplasts. Because each Trx isoform seems to have a distinct target selectivity, the electron distribution from FTR to multiple Trxs is thought to be the critical branch point for determining the consequence of chloroplast redox regulation. In the present study, we aimed to comprehensively characterize the kinetics of electron transfer from FTR to 10 Trx isoforms. We prepared the recombinant FTR protein from Arabidopsis in the heterodimeric form containing the Fe–S cluster. By reconstituting the FTR/Trx system in vitro, we showed that FTR prepared here was enzymatically active and suitable for uncovering biochemical features of chloroplast redox regulation. A series of redox state determinations using the thiol-modifying reagent, 4-acetamido-4′-maleimidylstilbene-2,2′-disulfonate, indicated that all chloroplast Trx isoforms are commonly reduced by FTR; however, significantly different efficiencies were evident. These differences were apparently correlated with the distinct midpoint redox potentials among Trxs. Even when the experiments were performed under conditions of hypothetical in vivo stoichiometry of FTR and Trxs, a similar trend in distinguishable electron transfers was observed. These data highlight an aspect of highly organized circuits in the chloroplast redox regulation network.
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Cytoplasmic RNP granules including stress granules and P bodies serve as sites of mRNA processing, contributing to the regulation of RNA metabolism. For more information, please see article by Ford Harrison et al, pages 1433–1454. Image provided by Dr James Shorter.
Research Article|
April 04 2017
Distinct electron transfer from ferredoxin–thioredoxin reductase to multiple thioredoxin isoforms in chloroplasts
Keisuke Yoshida;
1Laboratory for Chemistry and Life Science, Tokyo Institute of Technology, Nagatsuta 4259-R1-8, Midori-ku, Yokohama 226-8503, Japan
2Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Tokyo 102-0075, Japan
Correspondence: Keisuke Yoshida (yoshida.k.ao@m.titech.ac.jp) and Toru Hisabori (thisabor@res.titech.ac.jp)
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Toru Hisabori
1Laboratory for Chemistry and Life Science, Tokyo Institute of Technology, Nagatsuta 4259-R1-8, Midori-ku, Yokohama 226-8503, Japan
2Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Tokyo 102-0075, Japan
Correspondence: Keisuke Yoshida (yoshida.k.ao@m.titech.ac.jp) and Toru Hisabori (thisabor@res.titech.ac.jp)
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Publisher: Portland Press Ltd
Received:
December 16 2016
Revision Received:
February 22 2017
Accepted:
February 24 2017
Accepted Manuscript online:
February 28 2017
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 2017 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society
2017
Biochem J (2017) 474 (8): 1347–1360.
Article history
Received:
December 16 2016
Revision Received:
February 22 2017
Accepted:
February 24 2017
Accepted Manuscript online:
February 28 2017
Citation
Keisuke Yoshida, Toru Hisabori; Distinct electron transfer from ferredoxin–thioredoxin reductase to multiple thioredoxin isoforms in chloroplasts. Biochem J 15 April 2017; 474 (8): 1347–1360. doi: https://doi.org/10.1042/BCJ20161089
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