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Determining the Rate-Limiting Step for Light-Responsive Redox Regulation in Chloroplasts

Thiol-based redox regulation ensures light-responsive control of chloroplast functions. Light-derived signal is transferred in the form of reducing power from the photosynthetic electron transport chain to several redox-sensitive target proteins. Two types of protein, ferredoxin-thioredoxin reductas...

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Autores principales: Yoshida, Keisuke, Hisabori, Toru
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6262275/
https://www.ncbi.nlm.nih.gov/pubmed/30384474
http://dx.doi.org/10.3390/antiox7110153
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author Yoshida, Keisuke
Hisabori, Toru
author_facet Yoshida, Keisuke
Hisabori, Toru
author_sort Yoshida, Keisuke
collection PubMed
description Thiol-based redox regulation ensures light-responsive control of chloroplast functions. Light-derived signal is transferred in the form of reducing power from the photosynthetic electron transport chain to several redox-sensitive target proteins. Two types of protein, ferredoxin-thioredoxin reductase (FTR) and thioredoxin (Trx), are well recognized as the mediators of reducing power. However, it remains unclear which step in a series of redox-relay reactions is the critical bottleneck for determining the rate of target protein reduction. To address this, the redox behaviors of FTR, Trx, and target proteins were extensively characterized in vitro and in vivo. The FTR/Trx redox cascade was reconstituted in vitro using recombinant proteins from Arabidopsis. On the basis of this assay, we found that the FTR catalytic subunit and f-type Trx are rapidly reduced after the drive of reducing power transfer, irrespective of the presence or absence of their downstream target proteins. By contrast, three target proteins, fructose 1,6-bisphosphatase (FBPase), sedoheptulose 1,7-bisphosphatase (SBPase), and Rubisco activase (RCA) showed different reduction patterns; in particular, SBPase was reduced at a low rate. The in vivo study using Arabidopsis plants showed that the Trx family is commonly and rapidly reduced upon high light irradiation, whereas FBPase, SBPase, and RCA are differentially and slowly reduced. Both of these biochemical and physiological findings suggest that reducing power transfer from Trx to its target proteins is a rate-limiting step for chloroplast redox regulation, conferring distinct light-responsive redox behaviors on each of the targets.
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spelling pubmed-62622752018-11-29 Determining the Rate-Limiting Step for Light-Responsive Redox Regulation in Chloroplasts Yoshida, Keisuke Hisabori, Toru Antioxidants (Basel) Article Thiol-based redox regulation ensures light-responsive control of chloroplast functions. Light-derived signal is transferred in the form of reducing power from the photosynthetic electron transport chain to several redox-sensitive target proteins. Two types of protein, ferredoxin-thioredoxin reductase (FTR) and thioredoxin (Trx), are well recognized as the mediators of reducing power. However, it remains unclear which step in a series of redox-relay reactions is the critical bottleneck for determining the rate of target protein reduction. To address this, the redox behaviors of FTR, Trx, and target proteins were extensively characterized in vitro and in vivo. The FTR/Trx redox cascade was reconstituted in vitro using recombinant proteins from Arabidopsis. On the basis of this assay, we found that the FTR catalytic subunit and f-type Trx are rapidly reduced after the drive of reducing power transfer, irrespective of the presence or absence of their downstream target proteins. By contrast, three target proteins, fructose 1,6-bisphosphatase (FBPase), sedoheptulose 1,7-bisphosphatase (SBPase), and Rubisco activase (RCA) showed different reduction patterns; in particular, SBPase was reduced at a low rate. The in vivo study using Arabidopsis plants showed that the Trx family is commonly and rapidly reduced upon high light irradiation, whereas FBPase, SBPase, and RCA are differentially and slowly reduced. Both of these biochemical and physiological findings suggest that reducing power transfer from Trx to its target proteins is a rate-limiting step for chloroplast redox regulation, conferring distinct light-responsive redox behaviors on each of the targets. MDPI 2018-10-31 /pmc/articles/PMC6262275/ /pubmed/30384474 http://dx.doi.org/10.3390/antiox7110153 Text en © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Yoshida, Keisuke
Hisabori, Toru
Determining the Rate-Limiting Step for Light-Responsive Redox Regulation in Chloroplasts
title Determining the Rate-Limiting Step for Light-Responsive Redox Regulation in Chloroplasts
title_full Determining the Rate-Limiting Step for Light-Responsive Redox Regulation in Chloroplasts
title_fullStr Determining the Rate-Limiting Step for Light-Responsive Redox Regulation in Chloroplasts
title_full_unstemmed Determining the Rate-Limiting Step for Light-Responsive Redox Regulation in Chloroplasts
title_short Determining the Rate-Limiting Step for Light-Responsive Redox Regulation in Chloroplasts
title_sort determining the rate-limiting step for light-responsive redox regulation in chloroplasts
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6262275/
https://www.ncbi.nlm.nih.gov/pubmed/30384474
http://dx.doi.org/10.3390/antiox7110153
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