Antioxidants

Editorial

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4 pages, 179 KiB

Open AccessEditorial

Thioredoxin and Glutaredoxin Systems Antioxidants Special Issue

by Jean-Pierre Jacquot and Mirko Zaffagnini

Antioxidants 2019, 8(3), 68; https://doi.org/10.3390/antiox8030068 - 18 Mar 2019

Cited by 6 | Viewed by 3313

Abstract

The special issue on Thioredoxin and Glutaredoxin systems (http://www [...] Full article

(This article belongs to the Special Issue Thioredoxin and Glutaredoxin Systems)

Research

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14 pages, 3477 KiB

Open AccessArticle

Proteomic Analyses of Thioredoxins f and m Arabidopsis thaliana Mutants Indicate Specific Functions for These Proteins in Plants

by Juan Fernández-Trijueque, Antonio-Jesús Serrato and Mariam Sahrawy

Antioxidants 2019, 8(3), 54; https://doi.org/10.3390/antiox8030054 - 2 Mar 2019

Cited by 9 | Viewed by 4116

Abstract

A large number of plastidial thioredoxins (TRX) are present in chloroplast and the specificity versus the redundancy of their functions is currently under discussion. Several results have highlighted the fact that each TRX has a specific target protein and thus a specific function. [...] Read more.

A large number of plastidial thioredoxins (TRX) are present in chloroplast and the specificity versus the redundancy of their functions is currently under discussion. Several results have highlighted the fact that each TRX has a specific target protein and thus a specific function. In this study we have found that in vitro activation of the fructose-1,6-bisphosphatase (FBPase) enzyme is more efficient when f1 and f2 type thioredoxins (TRXs) are used, whilst the m3 type TRX did not have any effect. In addition, we have carried out a two-dimensional electrophoresis-gel to obtain the protein profiling analyses of the trxf1, f2, m1, m2, m3 and m4 Arabidopsis mutants. The results revealed quantitative alteration of 86 proteins and demonstrated that the lack of both the f and m type thioredoxins have diverse effects on the proteome. Interestingly, 68% of the differentially expressed proteins in trxf1 and trxf2 mutants were downregulated, whilst 75% were upregulated in trxm1, trxm2, trxm3 and trxm4 lines. The lack of TRX f1 provoked a higher number of down regulated proteins. The contrary occurred when TRX m4 was absent. Most of the differentially expressed proteins fell into the categories of metabolic processes, the Calvin–Benson cycle, photosynthesis, response to stress, hormone signalling and protein turnover. Photosynthesis, the Calvin–Benson cycle and carbon metabolism are the most affected processes. Notably, a significant set of proteins related to the answer to stress situations and hormone signalling were affected. Despite some studies being necessary to find specific target proteins, these results show signs that are suggest that the f and m type plastidial TRXs most likely have some additional specific functions. Full article

(This article belongs to the Special Issue Thioredoxin and Glutaredoxin Systems)

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17 pages, 1504 KiB

Open AccessArticle

Cytosolic Isocitrate Dehydrogenase from Arabidopsis thaliana Is Regulated by Glutathionylation

by Adnan Khan Niazi, Laetitia Bariat, Christophe Riondet, Christine Carapito, Amna Mhamdi, Graham Noctor and Jean-Philippe Reichheld

Antioxidants 2019, 8(1), 16; https://doi.org/10.3390/antiox8010016 - 8 Jan 2019

Cited by 23 | Viewed by 5122

Abstract

NADP-dependent (Nicotinamide Adénine Dinucléotide Phosphate-dependent) isocitrate dehydrogenases (NADP-ICDH) are metabolic enzymes involved in 2-oxoglutarate biosynthesis, but they also supply cells with NADPH. Different NADP-ICDH genes are found in Arabidopsis among which a single gene encodes for a cytosolic ICDH (cICDH) isoform. Here, we [...] Read more.

NADP-dependent (Nicotinamide Adénine Dinucléotide Phosphate-dependent) isocitrate dehydrogenases (NADP-ICDH) are metabolic enzymes involved in 2-oxoglutarate biosynthesis, but they also supply cells with NADPH. Different NADP-ICDH genes are found in Arabidopsis among which a single gene encodes for a cytosolic ICDH (cICDH) isoform. Here, we show that cICDH is susceptible to oxidation and that several cysteine (Cys) residues are prone to S-nitrosylation upon nitrosoglutathione (GSNO) treatment. Moreover, we identified a single S-glutathionylated cysteine Cys363 by mass-spectrometry analyses. Modeling analyses suggest that Cys363 is not located in the close proximity of the cICDH active site. In addition, mutation of Cys363 consistently does not modify the activity of cICDH. However, it does affect the sensitivity of the enzyme to GSNO, indicating that S-glutathionylation of Cys363 is involved in the inhibition of cICDH activity upon GSNO treatments. We also show that glutaredoxin are able to rescue the GSNO-dependent inhibition of cICDH activity, suggesting that they act as a deglutathionylation system in vitro. The glutaredoxin system, conversely to the thioredoxin system, is able to remove S-nitrosothiol adducts from cICDH. Finally, NADP-ICDH activities were decreased both in a catalase2 mutant and in mutants affected in thiol reduction systems, suggesting a role of the thiol reduction systems to protect NADP-ICDH activities in planta. In line with our observations in Arabidopsis, we found that the human recombinant NADP-ICDH activity is also sensitive to oxidation in vitro, suggesting that this redox mechanism might be shared by other ICDH isoforms. Full article

(This article belongs to the Special Issue Thioredoxin and Glutaredoxin Systems)

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20 pages, 3000 KiB

Open AccessArticle

Structural and Biochemical Insights into the Reactivity of Thioredoxin h1 from Chlamydomonas reinhardtii

by Christophe H. Marchand, Simona Fermani, Jacopo Rossi, Libero Gurrieri, Daniele Tedesco, Julien Henri, Francesca Sparla, Paolo Trost, Stéphane D. Lemaire and Mirko Zaffagnini

Antioxidants 2019, 8(1), 10; https://doi.org/10.3390/antiox8010010 - 1 Jan 2019

Cited by 13 | Viewed by 4579

Abstract

Thioredoxins (TRXs) are major protein disulfide reductases of the cell. Their redox activity relies on a conserved Trp-Cys-(Gly/Pro)-Pro-Cys active site bearing two cysteine (Cys) residues that can be found either as free thiols (reduced TRXs) or linked together by a disulfide bond (oxidized [...] Read more.

Thioredoxins (TRXs) are major protein disulfide reductases of the cell. Their redox activity relies on a conserved Trp-Cys-(Gly/Pro)-Pro-Cys active site bearing two cysteine (Cys) residues that can be found either as free thiols (reduced TRXs) or linked together by a disulfide bond (oxidized TRXs) during the catalytic cycle. Their reactivity is crucial for TRX activity, and depends on the active site microenvironment. Here, we solved and compared the 3D structure of reduced and oxidized TRX h1 from Chlamydomonas reinhardtii (CrTRXh1). The three-dimensional structure was also determined for mutants of each active site Cys. Structural alignments of CrTRXh1 with other structurally solved plant TRXs showed a common spatial fold, despite the low sequence identity. Structural analyses of CrTRXh1 revealed that the protein adopts an identical conformation independently from its redox state. Treatment with iodoacetamide (IAM), a Cys alkylating agent, resulted in a rapid and pH-dependent inactivation of CrTRXh1. Starting from fully reduced CrTRXh1, we determined the acid dissociation constant (pK_a) of each active site Cys by Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry analyses coupled to differential IAM-based alkylation. Based on the diversity of catalytic Cys deprotonation states, the mechanisms and structural features underlying disulfide redox activity are discussed. Full article

(This article belongs to the Special Issue Thioredoxin and Glutaredoxin Systems)

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9 pages, 1191 KiB

Open AccessArticle

New Insights into the Potential of Endogenous Redox Systems in Wheat Bread Dough

by Nicolas Navrot, Rikke Buhl Holstborg, Per Hägglund, Inge Lise Povlsen and Birte Svensson

Antioxidants 2018, 7(12), 190; https://doi.org/10.3390/antiox7120190 - 12 Dec 2018

Cited by 5 | Viewed by 3336

Abstract

Various redox compounds are known to influence the structure of the gluten network in bread dough, and hence its strength. The cereal thioredoxin system (NTS), composed of nicotinamide adenine dinucleotide phosphate (NADPH)-dependent thioredoxin reductase (NTR) and thioredoxin (Trx), is a major reducing enzymatic [...] Read more.

Various redox compounds are known to influence the structure of the gluten network in bread dough, and hence its strength. The cereal thioredoxin system (NTS), composed of nicotinamide adenine dinucleotide phosphate (NADPH)-dependent thioredoxin reductase (NTR) and thioredoxin (Trx), is a major reducing enzymatic system that is involved in seed formation and germination. NTS is a particularly interesting tool for food processing due to its heat stability and its broad range of protein substrates. We show here that barley NTS is capable of remodeling the gluten network and weakening bread dough. Furthermore, functional wheat Trx that is present in the dough can be recruited by the addition of recombinant barley NTR, resulting in dough weakening. These results confirm the potential of NTS, especially NTR, as a useful tool in baking for weakening strong doughs, or in flat product baking. Full article

(This article belongs to the Special Issue Thioredoxin and Glutaredoxin Systems)

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16 pages, 2188 KiB

Open AccessArticle

Redox Regulation of Monodehydroascorbate Reductase by Thioredoxin y in Plastids Revealed in the Context of Water Stress

by Hélène Vanacker, Marjorie Guichard, Anne-Sophie Bohrer and Emmanuelle Issakidis-Bourguet

Antioxidants 2018, 7(12), 183; https://doi.org/10.3390/antiox7120183 - 6 Dec 2018

Cited by 39 | Viewed by 4291

Abstract

Thioredoxins (TRXs) are key players within the complex response network of plants to environmental constraints. Here, the physiological implication of the plastidial y-type TRXs in Arabidopsis drought tolerance was examined. We previously showed that TRXs y1 and y2 have antioxidant functions, and here, [...] Read more.

Thioredoxins (TRXs) are key players within the complex response network of plants to environmental constraints. Here, the physiological implication of the plastidial y-type TRXs in Arabidopsis drought tolerance was examined. We previously showed that TRXs y1 and y2 have antioxidant functions, and here, the corresponding single and double mutant plants were studied in the context of water deprivation. TRX y mutant plants showed reduced stress tolerance in comparison with wild-type (WT) plants that correlated with an increase in their global protein oxidation levels. Furthermore, at the level of the main antioxidant metabolites, while glutathione pool size and redox state were similarly affected by drought stress in WT and trxy1y2 plants, ascorbate (AsA) became more quickly and strongly oxidized in mutant leaves. Monodehydroascorbate (MDA) is the primary product of AsA oxidation and NAD(P)H-MDA reductase (MDHAR) ensures its reduction. We found that the extractable leaf NADPH-dependent MDHAR activity was strongly activated by TRX y2. Moreover, activity of recombinant plastid Arabidopsis MDHAR isoform (MDHAR6) was specifically increased by reduced TRX y, and not by other plastidial TRXs. Overall, these results reveal a new function for y-type TRXs and highlight their role as major antioxidants in plastids and their importance in plant stress tolerance. Full article

(This article belongs to the Special Issue Thioredoxin and Glutaredoxin Systems)

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17 pages, 2278 KiB

Open AccessArticle

Crystal Structure of Chloroplastic Thioredoxin f2 from Chlamydomonas reinhardtii Reveals Distinct Surface Properties

by Stéphane D. Lemaire, Daniele Tedesco, Pierre Crozet, Laure Michelet, Simona Fermani, Mirko Zaffagnini and Julien Henri

Antioxidants 2018, 7(12), 171; https://doi.org/10.3390/antiox7120171 - 23 Nov 2018

Cited by 16 | Viewed by 4884

Abstract

Protein disulfide reduction by thioredoxins (TRXs) controls the conformation of enzyme active sites and their multimeric complex formation. TRXs are small oxidoreductases that are broadly conserved in all living organisms. In photosynthetic eukaryotes, TRXs form a large multigenic family, and they have been [...] Read more.

Protein disulfide reduction by thioredoxins (TRXs) controls the conformation of enzyme active sites and their multimeric complex formation. TRXs are small oxidoreductases that are broadly conserved in all living organisms. In photosynthetic eukaryotes, TRXs form a large multigenic family, and they have been classified in different types: f, m, x, y, and z types are chloroplastic, while o and h types are located in mitochondria and cytosol. In the model unicellular alga Chlamydomonas reinhardtii, the TRX family contains seven types, with f- and h-types represented by two isozymes. Type-f TRXs interact specifically with targets in the chloroplast, controlling photosynthetic carbon fixation by the Calvin–Benson cycle. We solved the crystal structures of TRX f2 and TRX h1 from C. reinhardtii. The systematic comparison of their atomic features revealed a specific conserved electropositive crown around the active site of TRX f, complementary to the electronegative surface of their targets. We postulate that this surface provides specificity to each type of TRX. Full article

(This article belongs to the Special Issue Thioredoxin and Glutaredoxin Systems)

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11 pages, 2603 KiB

Open AccessArticle

Crystal Structure of the Apo-Form of NADPH-Dependent Thioredoxin Reductase from a Methane-Producing Archaeon

by Rubén M. Buey, Ruth A. Schmitz, Bob B. Buchanan and Monica Balsera

Antioxidants 2018, 7(11), 166; https://doi.org/10.3390/antiox7110166 - 17 Nov 2018

Cited by 6 | Viewed by 4387

Abstract

The redox regulation of proteins via reversible dithiol/disulfide exchange reactions involves the thioredoxin system, which is composed of a reductant, a thioredoxin reductase (TR), and thioredoxin (Trx). In the pyridine nucleotide-dependent Trx reduction pathway, reducing equivalents, typically from reduced nicotinamide adenine dinucleotide phosphate [...] Read more.

The redox regulation of proteins via reversible dithiol/disulfide exchange reactions involves the thioredoxin system, which is composed of a reductant, a thioredoxin reductase (TR), and thioredoxin (Trx). In the pyridine nucleotide-dependent Trx reduction pathway, reducing equivalents, typically from reduced nicotinamide adenine dinucleotide phosphate (NADPH), are transferred from NADPH-TR (NTR) to Trx and, in turn, to target proteins, thus resulting in the reversible modification of the structural and functional properties of the targets. NTR enzymes contain three functional sites: an NADPH binding pocket, a non-covalently bound flavin cofactor, and a redox-active disulfide in the form of CxxC. With the aim of increasing our knowledge of the thioredoxin system in archaea, we here report the high-resolution crystal structure of NTR from the methane-generating organism Methanosarcina mazei strain Gö1 (MmNTR) at 2.6 Å resolution. Based on the crystals presently described, MmNTR assumes an overall fold that is nearly identical to the archetypal fold of authentic NTRs; however, surprisingly, we observed no electron density for flavin adenine dinucleotide (FAD) despite the well-defined and conserved FAD-binding cavity in the folded module. Remarkably, the dimers of the apo-protein within the crystal were different from those observed by small angle X-ray scattering (SAXS) for the holo-protein, suggesting that the binding of the flavin cofactor does not require major protein structural rearrangements. Rather, binding results in the stabilization of essential parts of the structure, such as those involved in dimer stabilization. Altogether, this structure represents the example of an apo-form of an NTR that yields important insight into the effects of the cofactor on protein folding. Full article

(This article belongs to the Special Issue Thioredoxin and Glutaredoxin Systems)

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15 pages, 2250 KiB

Open AccessArticle

Characterization of TrxC, an Atypical Thioredoxin Exclusively Present in Cyanobacteria

by Luis López-Maury, Luis G. Heredia-Martínez and Francisco J. Florencio

Antioxidants 2018, 7(11), 164; https://doi.org/10.3390/antiox7110164 - 13 Nov 2018

Cited by 8 | Viewed by 4522

Abstract

Cyanobacteria form a diverse group of oxygenic photosynthetic prokaryotes considered to be the antecessor of plant chloroplast. They contain four different thioredoxins isoforms, three of them corresponding to m, x and y type present in plant chloroplast, while the fourth one (named [...] Read more.

Cyanobacteria form a diverse group of oxygenic photosynthetic prokaryotes considered to be the antecessor of plant chloroplast. They contain four different thioredoxins isoforms, three of them corresponding to m, x and y type present in plant chloroplast, while the fourth one (named TrxC) is exclusively found in cyanobacteria. TrxC has a modified active site (WCGLC) instead of the canonical (WCGPC) present in most thioredoxins. We have purified it and assayed its activity but surprisingly TrxC lacked all the classical activities, such as insulin precipitation or activation of the fructose-1,6-bisphosphatase. Mutants lacking trxC or over-expressing it were generated in the model cyanobacterium Synechocystis sp. PCC 6803 and their phenotypes have been analyzed. The ΔtrxC mutant grew at similar rates to WT in all conditions tested although it showed an increased carotenoid content especially under low carbon conditions. Overexpression strains showed reduced growth under the same conditions and accumulated lower amounts of carotenoids. They also showed lower oxygen evolution rates at high light but higher Fv’/Fm’ and Non-photochemical-quenching (NPQ) in dark adapted cells, suggesting a more oxidized plastoquinone pool. All these data suggest that TrxC might have a role in regulating photosynthetic adaptation to low carbon and/or high light conditions. Full article

(This article belongs to the Special Issue Thioredoxin and Glutaredoxin Systems)

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8 pages, 1538 KiB

Open AccessArticle

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

by Keisuke Yoshida and Toru Hisabori

Antioxidants 2018, 7(11), 153; https://doi.org/10.3390/antiox7110153 - 31 Oct 2018

Cited by 22 | Viewed by 4398

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Thioredoxin and Glutaredoxin Systems)

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14 pages, 6368 KiB

Open AccessArticle

Towards Initial Indications for a Thiol-Based Redox Control of Arabidopsis 5-Aminolevulinic Acid Dehydratase

by Daniel Wittmann, Sigri Kløve, Peng Wang and Bernhard Grimm

Antioxidants 2018, 7(11), 152; https://doi.org/10.3390/antiox7110152 - 31 Oct 2018

Cited by 9 | Viewed by 4485

Abstract

Thiol-based redox control is one of the important posttranslational mechanisms of the tetrapyrrole biosynthesis pathway. Many enzymes of the pathway have been shown to interact with thioredoxin (TRX) and Nicotinamide adenine dinucleotide phosphate (NADPH)-dependent thioredoxin reductase C (NTRC). We examined the redox-dependency of [...] Read more.

Thiol-based redox control is one of the important posttranslational mechanisms of the tetrapyrrole biosynthesis pathway. Many enzymes of the pathway have been shown to interact with thioredoxin (TRX) and Nicotinamide adenine dinucleotide phosphate (NADPH)-dependent thioredoxin reductase C (NTRC). We examined the redox-dependency of 5-aminolevulinic acid dehydratase (ALAD), which catalyzed the conjugation of two 5-aminolevulinic acid (ALA) molecules to porphobilinogen. ALAD interacted with TRX f, TRX m and NTRC in chloroplasts. Consequently, less ALAD protein accumulated in the trx f1, ntrc and trx f1/ntrc mutants compared to wild-type control resulting in decreased ALAD activity. In a polyacrylamide gel under non-reducing conditions, ALAD monomers turned out to be present in reduced and two oxidized forms. The reduced and oxidized forms of ALAD differed in their catalytic activity. The addition of TRX stimulated ALAD activity. From our results it was concluded that (i) deficiency of the reducing power mainly affected the in planta stability of ALAD; and (ii) the reduced form of ALAD displayed increased enzymatic activity. Full article

(This article belongs to the Special Issue Thioredoxin and Glutaredoxin Systems)

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21 pages, 3703 KiB

Open AccessArticle

Mitochondrial Arabidopsis thaliana TRXo Isoforms Bind an Iron–Sulfur Cluster and Reduce NFU Proteins In Vitro

by Flavien Zannini, Thomas Roret, Jonathan Przybyla-Toscano, Tiphaine Dhalleine, Nicolas Rouhier and Jérémy Couturier

Antioxidants 2018, 7(10), 142; https://doi.org/10.3390/antiox7100142 - 13 Oct 2018

Cited by 22 | Viewed by 4927

Abstract

In plants, the mitochondrial thioredoxin (TRX) system generally comprises only one or two isoforms belonging to the TRX h or o classes, being less well developed compared to the numerous isoforms found in chloroplasts. Unlike most other plant species, Arabidopsis thaliana possesses two [...] Read more.

In plants, the mitochondrial thioredoxin (TRX) system generally comprises only one or two isoforms belonging to the TRX h or o classes, being less well developed compared to the numerous isoforms found in chloroplasts. Unlike most other plant species, Arabidopsis thaliana possesses two TRXo isoforms whose physiological functions remain unclear. Here, we performed a structure–function analysis to unravel the respective properties of the duplicated TRXo1 and TRXo2 isoforms. Surprisingly, when expressed in Escherichia coli, both recombinant proteins existed in an apo-monomeric form and in a homodimeric iron–sulfur (Fe-S) cluster-bridged form. In TRXo2, the [4Fe-4S] cluster is likely ligated in by the usual catalytic cysteines present in the conserved Trp-Cys-Gly-Pro-Cys signature. Solving the three-dimensional structure of both TRXo apo-forms pointed to marked differences in the surface charge distribution, notably in some area usually participating to protein–protein interactions with partners. However, we could not detect a difference in their capacity to reduce nitrogen-fixation-subunit-U (NFU)-like proteins, NFU4 or NFU5, two proteins participating in the maturation of certain mitochondrial Fe-S proteins and previously isolated as putative TRXo1 partners. Altogether, these results suggest that a novel regulation mechanism may prevail for mitochondrial TRXs o, possibly existing as a redox-inactive Fe-S cluster-bound form that could be rapidly converted in a redox-active form upon cluster degradation in specific physiological conditions. Full article

(This article belongs to the Special Issue Thioredoxin and Glutaredoxin Systems)

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Review

Jump to: Editorial, Research

22 pages, 2006 KiB

Open AccessReview

The Oxidized Protein Repair Enzymes Methionine Sulfoxide Reductases and Their Roles in Protecting against Oxidative Stress, in Ageing and in Regulating Protein Function

by Sofia Lourenço dos Santos, Isabelle Petropoulos and Bertrand Friguet

Antioxidants 2018, 7(12), 191; https://doi.org/10.3390/antiox7120191 - 12 Dec 2018

Cited by 65 | Viewed by 7675

Abstract

Cysteine and methionine residues are the amino acids most sensitive to oxidation by reactive oxygen species. However, in contrast to other amino acids, certain cysteine and methionine oxidation products can be reduced within proteins by dedicated enzymatic repair systems. Oxidation of cysteine first [...] Read more.

Cysteine and methionine residues are the amino acids most sensitive to oxidation by reactive oxygen species. However, in contrast to other amino acids, certain cysteine and methionine oxidation products can be reduced within proteins by dedicated enzymatic repair systems. Oxidation of cysteine first results in either the formation of a disulfide bridge or a sulfenic acid. Sulfenic acid can be converted to disulfide or sulfenamide or further oxidized to sulfinic acid. Disulfide can be easily reversed by different enzymatic systems such as the thioredoxin/thioredoxin reductase and the glutaredoxin/glutathione/glutathione reductase systems. Methionine side chains can also be oxidized by reactive oxygen species. Methionine oxidation, by the addition of an extra oxygen atom, leads to the generation of methionine sulfoxide. Enzymatically catalyzed reduction of methionine sulfoxide is achieved by either methionine sulfoxide reductase A or methionine sulfoxide reductase B, also referred as to the methionine sulfoxide reductases system. This oxidized protein repair system is further described in this review article in terms of its discovery and biologically relevant characteristics, and its important physiological roles in protecting against oxidative stress, in ageing and in regulating protein function. Full article

(This article belongs to the Special Issue Thioredoxin and Glutaredoxin Systems)

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17 pages, 913 KiB

Open AccessReview

Involvement of Glutaredoxin and Thioredoxin Systems in the Nitrogen-Fixing Symbiosis between Legumes and Rhizobia

by Geneviève Alloing, Karine Mandon, Eric Boncompagni, Françoise Montrichard and Pierre Frendo

Antioxidants 2018, 7(12), 182; https://doi.org/10.3390/antiox7120182 - 5 Dec 2018

Cited by 20 | Viewed by 5668

Abstract

Leguminous plants can form a symbiotic relationship with Rhizobium bacteria, during which plants provide bacteria with carbohydrates and an environment appropriate to their metabolism, in return for fixed atmospheric nitrogen. The symbiotic interaction leads to the formation of a new organ, the root [...] Read more.

Leguminous plants can form a symbiotic relationship with Rhizobium bacteria, during which plants provide bacteria with carbohydrates and an environment appropriate to their metabolism, in return for fixed atmospheric nitrogen. The symbiotic interaction leads to the formation of a new organ, the root nodule, where a coordinated differentiation of plant cells and bacteria occurs. The establishment and functioning of nitrogen-fixing symbiosis involves a redox control important for both the plant-bacteria crosstalk and the regulation of nodule metabolism. In this review, we discuss the involvement of thioredoxin and glutaredoxin systems in the two symbiotic partners during symbiosis. The crucial role of glutathione in redox balance and S-metabolism is presented. We also highlight the specific role of some thioredoxin and glutaredoxin systems in bacterial differentiation. Transcriptomics data concerning genes encoding components and targets of thioredoxin and glutaredoxin systems in connection with the developmental step of the nodule are also considered in the model system Medicago truncatula–Sinorhizobium meliloti. Full article

(This article belongs to the Special Issue Thioredoxin and Glutaredoxin Systems)

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15 pages, 803 KiB

Open AccessReview

Reactive Oxygen Species and the Redox-Regulatory Network in Cold Stress Acclimation

by Anna Dreyer and Karl-Josef Dietz

Antioxidants 2018, 7(11), 169; https://doi.org/10.3390/antiox7110169 - 21 Nov 2018

Cited by 104 | Viewed by 6660

Abstract

Cold temperatures restrict plant growth, geographical extension of plant species, and agricultural practices. This review deals with cold stress above freezing temperatures often defined as chilling stress. It focuses on the redox regulatory network of the cell under cold temperature conditions. Reactive oxygen [...] Read more.

Cold temperatures restrict plant growth, geographical extension of plant species, and agricultural practices. This review deals with cold stress above freezing temperatures often defined as chilling stress. It focuses on the redox regulatory network of the cell under cold temperature conditions. Reactive oxygen species (ROS) function as the final electron sink in this network which consists of redox input elements, transmitters, targets, and sensors. Following an introduction to the critical network components which include nicotinamide adenine dinucleotide phosphate (NADPH)-dependent thioredoxin reductases, thioredoxins, and peroxiredoxins, typical laboratory experiments for cold stress investigations will be described. Short term transcriptome and metabolome analyses allow for dissecting the early responses of network components and complement the vast data sets dealing with changes in the antioxidant system and ROS. This review gives examples of how such information may be integrated to advance our knowledge on the response and function of the redox regulatory network in cold stress acclimation. It will be exemplarily shown that targeting the redox network might be beneficial and supportive to improve cold stress acclimation and plant yield in cold climate. Full article

(This article belongs to the Special Issue Thioredoxin and Glutaredoxin Systems)

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23 pages, 2665 KiB

Open AccessReview

Hydrogen Peroxide and Redox Regulation of Developments

by Christine Rampon, Michel Volovitch, Alain Joliot and Sophie Vriz

Antioxidants 2018, 7(11), 159; https://doi.org/10.3390/antiox7110159 - 6 Nov 2018

Cited by 65 | Viewed by 7735

Abstract

Reactive oxygen species (ROS), which were originally classified as exclusively deleterious compounds, have gained increasing interest in the recent years given their action as bona fide signalling molecules. The main target of ROS action is the reversible oxidation of cysteines, leading to the [...] Read more.

Reactive oxygen species (ROS), which were originally classified as exclusively deleterious compounds, have gained increasing interest in the recent years given their action as bona fide signalling molecules. The main target of ROS action is the reversible oxidation of cysteines, leading to the formation of disulfide bonds, which modulate protein conformation and activity. ROS, endowed with signalling properties, are mainly produced by NADPH oxidases (NOXs) at the plasma membrane, but their action also involves a complex machinery of multiple redox-sensitive protein families that differ in their subcellular localization and their activity. Given that the levels and distribution of ROS are highly dynamic, in part due to their limited stability, the development of various fluorescent ROS sensors, some of which are quantitative (ratiometric), represents a clear breakthrough in the field and have been adapted to both ex vivo and in vivo applications. The physiological implication of ROS signalling will be presented mainly in the frame of morphogenetic processes, embryogenesis, regeneration, and stem cell differentiation. Gain and loss of function, as well as pharmacological strategies, have demonstrated the wide but specific requirement of ROS signalling at multiple stages of these processes and its intricate relationship with other well-known signalling pathways. Full article

(This article belongs to the Special Issue Thioredoxin and Glutaredoxin Systems)

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26 pages, 1009 KiB

Open AccessReview

Physiological Roles of Plant Methionine Sulfoxide Reductases in Redox Homeostasis and Signaling

by Pascal Rey and Lionel Tarrago

Antioxidants 2018, 7(9), 114; https://doi.org/10.3390/antiox7090114 - 29 Aug 2018

Cited by 67 | Viewed by 7478

Abstract

Oxidation of methionine (Met) leads to the formation of two S- and R-diastereoisomers of Met sulfoxide (MetO) that are reduced back to Met by methionine sulfoxide reductases (MSRs), A and B, respectively. Here, we review the current knowledge about the physiological [...] Read more.

Oxidation of methionine (Met) leads to the formation of two S- and R-diastereoisomers of Met sulfoxide (MetO) that are reduced back to Met by methionine sulfoxide reductases (MSRs), A and B, respectively. Here, we review the current knowledge about the physiological functions of plant MSRs in relation with subcellular and tissue distribution, expression patterns, mutant phenotypes, and possible targets. The data gained from modified lines of plant models and crop species indicate that MSRs play protective roles upon abiotic and biotic environmental constraints. They also participate in the control of the ageing process, as shown in seeds subjected to adverse conditions. Significant advances were achieved towards understanding how MSRs could fulfil these functions via the identification of partners among Met-rich or MetO-containing proteins, notably by using redox proteomic approaches. In addition to a global protective role against oxidative damage in proteins, plant MSRs could specifically preserve the activity of stress responsive effectors such as glutathione-S-transferases and chaperones. Moreover, several lines of evidence indicate that MSRs fulfil key signaling roles via interplays with Ca²⁺- and phosphorylation-dependent cascades, thus transmitting ROS-related information in transduction pathways. Full article

(This article belongs to the Special Issue Thioredoxin and Glutaredoxin Systems)

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