Thioredoxin

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Yves Meyer - One of the best experts on this subject based on the ideXlab platform.

  • Interaction of Thioredoxins with target proteins: role of particular structural elements and electrostatic properties of Thioredoxins in their interplay with 2-oxoacid dehydrogenase complexes.
    Protein Science, 2008
    Co-Authors: Victoria I. Bunik, Yves Meyer, Jean-pierre Jacquot, Günter Raddatz, Stéphane D. Lemaire, Hans Bisswanger
    Abstract:

    The Thioredoxin action upon the 2-oxoacid dehydrogenase complexes is investigated by using different Thioredoxins, both wild-type and mutated. The attacking cysteine residue of Thioredoxin is established to be essential for the Thioredoxin-dependent activation of the complexes. Mutation of the buried cysteine residue to serine is not crucial for the activation, but prevents inhibition of the complexes, exhibited by the Clamydomonas reinhardtii Thioredoxin m disulfide. Site-directed mutagenesis of D26, W31, F/W12, and Y/A70 (the Escherichia coli Thioredoxin numbering is employed for all the Thioredoxins studied) indicates that both the active site and remote residues of Thioredoxin are involved in its interplay with the 2-oxoacid dehydrogenase complexes. Sequences of 11 Thioredoxin species tested biochemically are aligned. The Thioredoxin residues at the contact between the alpha3/3(10) and alpha1 helices, the length of the alpha1 helix and the charges in the alpha2-beta3 and beta4-beta5 linkers are found to correlate with the protein influence on the 2-oxoacid dehydrogenase complexes (the secondary structural elements of Thioredoxin are defined according to Eklund H et al., 1991, Proteins 11:13-28). The distribution of the charges on the surface of the Thioredoxin molecules is analyzed. The analysis reveals the species specific polarization of the Thioredoxin active site surroundings, which corresponds to the efficiency of the Thioredoxin interplay with the 2-oxoacid dehydrogenase systems. The most effective mitochondrial Thioredoxin is characterized by the strongest polarization of this area and the highest value of the electrostatic dipole vector of the molecule. Not only the magnitude, but also the orientation of the dipole vector show correlation with the Thioredoxin action. The dipole direction is found to be significantly influenced by the charges of the residues 13/14, 51, and 83/85, which distinguish the activating and inhibiting Thioredoxin disulfides.

  • Glutaredoxins and Thioredoxins in plants.
    Biochimica et biophysica acta, 2007
    Co-Authors: Yves Meyer, Florence Vignols, Christophe Riondet, Wafi Siala, Talaat Bashandy, Jean Philippe Reichheld
    Abstract:

    During the 70s and 80s two plant Thioredoxin systems were identified. The chloroplastic system is composed of a ferredoxin-dependent Thioredoxin, with two Thioredoxin types (m and f) regulating the activity of enzymes implicated in photosynthetic carbon assimilation. In the cytosol of heterotrophic tissues, an NADP dependent Thioredoxin reductase and a Thioredoxin (h) were identified. The first plant glutaredoxin was only identified later, in 1994. Our view of plant Thioredoxins and glutaredoxins was profoundly modified by the sequencing programs which revealed an unexpected number of genes encoding not only the previously identified disulfide reductases, but also numerous new types. At the same time it became clear that plant genomes encode chloroplastic, cytosolic and mitochondrial peroxiredoxins, suggesting a major role for redoxins in anti-oxidant defense. Efficient proteomics approaches were developed allowing the characterization of numerous Thioredoxin target proteins. They are implicated in different aspects of plant life including development and adaptation to environmental changes and stresses. The most important challenge for the next years will probably be to identify in planta which redoxin reduces which target, a question which remains unsolved due to the low specificities of redoxins in vitro and the numerous redundancies which in most cases mask the phenotype of redoxin mutants.

  • Evolution of redoxin genes in the green lineage.
    Photosynthesis Research, 2006
    Co-Authors: Yves Meyer, Jean Philippe Reichheld, Christophe Riondet, Laure Constans, Mohamed Ragab Abdelgawwad, Florence Vignols
    Abstract:

    The availability of the Arabidopsis genome revealed the complexity of the gene families implicated in dithiol disulfide exchanges. Most non-green organisms present less dithiol oxidoreductase genes. The availability of the almost complete genome sequence of rice now allows a systematic search for Thioredoxins, glutaredoxins and their reducers. This shows that all redoxin families previously defined for Arabidopsis have members in the rice genome and that all the deduced rice redoxins fall within these families. This establishes that the redoxin classification applies both to dicots and monocots. Nevertheless, within each redoxin type the number of members is not the same in these two higher plants and it is not always possible to define orthologues between rice and Arabidopsis. The sequencing of two unicellular algae (Chlamydomonas and Ostreococcus) genomes are almost finished. This allowed us to follow the origin of the different gene families in the green lineage. It appears that most Thioredoxin and glutaredoxin types, their chloroplastic, mitochondrial and cytosolic reducers are always present in these unicellular organisms. Nevertheless, striking differences appear in comparison to higher plant redoxins. Some Thioredoxin types are not present in these algal genomes including Thioredoxins o, clot and glutaredoxins CCxC. Numerous redoxins, including the cytosolic Thioredoxins, do not fit with the corresponding higher plant classification. In addition both algae present a NADPH-dependent Thioredoxin reductase with a selenocysteine which is highly similar to the animal Thioredoxin reductases, a type of Thioredoxin reductase not present in higher plants.

  • Thioredoxins in Arabidopsis and other plants.
    Photosynthesis Research, 2005
    Co-Authors: Yves Meyer, Jean Philippe Reichheld, Florence Vignols
    Abstract:

    Regulation of disulfide dithiol exchange has become increasingly important in our knowledge of plant life. Initially discovered as regulators of light-dependent malate biosynthesis in the chloroplast, plant Thioredoxins are now implicated in a large panel of reactions related to metabolism, defense and development. In this review we describe the numerous Thioredoxin types encoded by the Arabidopsis genome, and provide evidence that they are present in all higher plants. Some results suggest cross-talk between Thioredoxins and glutaredoxins, the second family of disulfide dithiol reductase. The development of proteomics in plants revealed an unexpectedly large number of putative target proteins for Thioredoxins and glutaredoxins. Nevertheless, we are far from a clear understanding of the actual function of each Thioredoxin in planta. Although hampered by functional redundancies between genes, genetic approaches are probably unavoidable to define which Thioredoxin interacts with which target protein and evaluate the physiological consequences.

  • Cytosolic, Mitochondrial Thioredoxins and Thioredoxin Reductases in Arabidopsis Thaliana
    Photosynthesis Research, 2004
    Co-Authors: Claire Bréhélin, Christophe Laloi, Aaron Setterdahl, David Knaff, Yves Meyer
    Abstract:

    Thioredoxins, by reducing disulfide bridges are one of the main participants that regulate cellular redox balance. In plants, the Thioredoxin system is particularly complex. The most well-known Thioredoxins are the chloroplastic ones, that participate in the regulation of enzymatic activities during the transition between light and dark phases. The mitochondrial system composed of NADPH-dependent Thioredoxin reductase and type o Thioredoxin has only recently been described. The type h Thioredoxin group is better known. Yeast complementation experiments demonstrated that Arabidopsis thaliana Thioredoxins h have divergent functions, at least in Saccharomyces cerevisiae. They have diverse affinities for different target proteins, most probably because of structural differences. However, plant Thioredoxin h functions still have to be defined. Abbreviations: mBBr-monobromobimane; NADPH-nicotinamide adenine dinucleotide; NTR-NADPH Thioredoxin reductase

Jean-pierre Jacquot - One of the best experts on this subject based on the ideXlab platform.

  • Dithiol disulphide exchange in redox regulation of chloroplast enzymes in response to evolutionary and structural constraints
    Plant Science, 2017
    Co-Authors: Desirée D. Gütle, Thomas Roret, Arnaud Hecker, Ralf Reski, Jean-pierre Jacquot
    Abstract:

    Redox regulation of chloroplast enzymes via disulphide reduction is believed to control the rates of CO2 fixation. The study of the Thioredoxin reduction pathways and of various target enzymes lead to the following guidelines: i) Thioredoxin gene content is greatly higher in photosynthetic eukaryotes compared to prokaryotes; ii) Thioredoxin-reducing pathways have expanded in photosynthetic eukaryotes with four different Thioredoxin reductases and the possibility to reduce some Thioredoxins via glutaredoxins; iii) Some enzymes that were thought to be strictly linked to photosynthesis ferredoxin-Thioredoxin reductase, phosphoribulokinase, ribulose-1,5-bisphosphate carboxylase/oxygenase, sedoheptulose-1,7-bisphosphatase are present in non-photosynthetic organisms; iv) Photosynthetic eukaryotes contain a genetic patchwork of sequences borrowed from prokaryotes including α–proteobacteria and archaea; v) The introduction of redox regulatory sequences did not occur at the same place for all targets. Some possess critical cysteines in cyanobacteria, for others the transition occurred rather at the green algae level; vi) Generally the regulatory sites of the target enzymes are distally located from the catalytic sites. The cysteine residues are generally not involved in catalysis. Following reduction, molecular movements open the active sites and make catalysis possible; vii) The regulatory sequences are located on surface-accessible loops. At least one instance they can be cut out and serve as signal peptides for inducing plant defence.

  • Glutaredoxin: The Missing Link Between Thiol-Disulfide Oxidoreductases and Iron Sulfur Enzymes
    2009
    Co-Authors: Benjamin Selles, Nicolas Rouhier, Kamel Chibani, Jérémy Couturier, Filipe Gama, Jean-pierre Jacquot
    Abstract:

    The CXXC motif is present in many disulfide oxidoreductases as Thioredoxins, glutaredoxins, and protein disulfide isomerases. It is also present in several metalbinding structures including hemoproteins and iron sulfur proteins. Although the 3D structure of ferredoxins and Thioredoxins is radically different, the presence of this motif in both proteins suggests that Thioredoxins and their derivatives might be able to accommodate iron sulfur centers (ISCs) as well. Several studies have indeed proven the presence of metals, such as iron or zinc, in Thioredoxin-like structures either as natural products or after mutagenesis as in Escherichia coli Thioredoxin 1. Moreover, it was recently demonstrated that some glutaredoxin species with CGYC or CGFS active sites can assemble a [2Fe–2S] ISC in a homodimer. Quite surprisingly, the ligands are the glutaredoxin catalytic cysteine and an external glutathione molecule. As a yeast CGFS glutaredoxin is thought to be involved in the transfer of preassembled ISCs from scaffold to acceptor apoproteins, this suggests that glutaredoxins are involved in these pathways through their own capacity to assemble such centers and transfer them efficiently. Altogether, these data provide firm evidence that glutaredoxins are a link between the world of thiol-disulfide reductases and iron sulfur enzymes.

  • Comparative genomic study of the Thioredoxin family in photosynthetic organisms with emphasis on populus trichocarpa
    Molecular Plant, 2009
    Co-Authors: Kamel Chibani, Jean-pierre Jacquot, Gunnar Wingsle, Nicolas Rouhier
    Abstract:

    The recent genome sequencing of Populus trichocarpa and Vitis vinifera, two models of woody plants, of Sorghum bicolor, a model of monocot using C4 metabolism, and of the moss Physcomitrella patens, together with the availability of photosynthetic organism genomes allows performance of a comparative genomic study with organisms having different ways of life, reproduction modes, biological traits, and physiologies. Thioredoxins (Trxs) are small ubiquitous proteins involved in the reduction of disulfide bridges in a variety of target enzymes present in all sub-cellular compartments and involved in many biochemical reactions. The genes coding for these enzymes have been identified in these newly sequenced genomes and annotated. The gene content, organization and distribution were compared to other photosynthetic organisms, leading to a refined classification. This analysis revealed that higher plants and bryophytes have a more complex family compared to algae and cyanobacteria and to non-photosynthetic organisms, since poplar exhibits 49 genes coding for typical and atypical Thioredoxins and Thioredoxin reductases, namely one-third more than monocots such as Oryza sativa and S. bicolor. The higher number of Trxs in poplar is partially explained by gene duplication in the Trx m, h, and nucleoredoxin classes. Particular attention was paid to poplar genes with emphasis on Trx-like classes called Clot, Thioredoxin-like, Thioredoxins of the lilium type and nucleoredoxins, which were not described in depth in previous genomic studies.

  • Interaction of Thioredoxins with target proteins: role of particular structural elements and electrostatic properties of Thioredoxins in their interplay with 2-oxoacid dehydrogenase complexes.
    Protein Science, 2008
    Co-Authors: Victoria I. Bunik, Yves Meyer, Jean-pierre Jacquot, Günter Raddatz, Stéphane D. Lemaire, Hans Bisswanger
    Abstract:

    The Thioredoxin action upon the 2-oxoacid dehydrogenase complexes is investigated by using different Thioredoxins, both wild-type and mutated. The attacking cysteine residue of Thioredoxin is established to be essential for the Thioredoxin-dependent activation of the complexes. Mutation of the buried cysteine residue to serine is not crucial for the activation, but prevents inhibition of the complexes, exhibited by the Clamydomonas reinhardtii Thioredoxin m disulfide. Site-directed mutagenesis of D26, W31, F/W12, and Y/A70 (the Escherichia coli Thioredoxin numbering is employed for all the Thioredoxins studied) indicates that both the active site and remote residues of Thioredoxin are involved in its interplay with the 2-oxoacid dehydrogenase complexes. Sequences of 11 Thioredoxin species tested biochemically are aligned. The Thioredoxin residues at the contact between the alpha3/3(10) and alpha1 helices, the length of the alpha1 helix and the charges in the alpha2-beta3 and beta4-beta5 linkers are found to correlate with the protein influence on the 2-oxoacid dehydrogenase complexes (the secondary structural elements of Thioredoxin are defined according to Eklund H et al., 1991, Proteins 11:13-28). The distribution of the charges on the surface of the Thioredoxin molecules is analyzed. The analysis reveals the species specific polarization of the Thioredoxin active site surroundings, which corresponds to the efficiency of the Thioredoxin interplay with the 2-oxoacid dehydrogenase systems. The most effective mitochondrial Thioredoxin is characterized by the strongest polarization of this area and the highest value of the electrostatic dipole vector of the molecule. Not only the magnitude, but also the orientation of the dipole vector show correlation with the Thioredoxin action. The dipole direction is found to be significantly influenced by the charges of the residues 13/14, 51, and 83/85, which distinguish the activating and inhibiting Thioredoxin disulfides.

  • An atypical catalytic mechanism involving three cysteines of Thioredoxin
    Journal of Biological Chemistry, 2008
    Co-Authors: Cha San Koh, David Knaff, Jean-pierre Jacquot, Nicolas Rouhier, Nicolas Navrot, Masakazu Hirasawa, Gunnar Wingsle, Claude Didierjean, Razip Samian, Catherine Corbier
    Abstract:

    Unlike other Thioredoxins h characterized so far, a poplar Thioredoxin of the h type, PtTrxh4, is reduced by glutathione and glutaredoxin (Grx) but not NADPH:Thioredoxin reductase (NTR). PtTrxh4 contains three cysteines: one localized in an N-terminal extension (Cys4) and two (Cys58 and Cys61) in the classical Thioredoxin active site (57WCGPC61). The property of a mutant in which Cys58 was replaced by serine demonstrates that it is responsible for the initial nucleophilic attack during the catalytic cycle. The observation that the C4S mutant is inactive in the presence of Grx but fully active when dithiothreitol is used as a reductant indicates that Cys4 is required for the regeneration of PtTrxh4 by Grx. Biochemical and x-ray crystallographic studies indicate that two intramolecular disulfide bonds involving Cys58 can be formed, linking it to either Cys61 or Cys4. We propose thus a four-step disulfide cascade mechanism involving the transient glutathionylation of Cys4 to convert this atypical Thioredoxin h back to its active reduced form.

David Knaff - One of the best experts on this subject based on the ideXlab platform.

  • Oxidation-reduction properties of Thioredoxins and Thioredoxin-regulated enzymes.
    Physiologia Plantarum, 2008
    Co-Authors: David Knaff
    Abstract:

    Oxidation-reduction midpoint potentials have been measured for the two chloroplast Thioredoxins, Thioredoxin f and m, for ferredoxin:Thioredoxin reductase (FTR) and for the Thioredoxin-regulated enzymes fructose-1,6-bisphosphatase (FBPase), phosphoribulokinase and NADP-malate dehydrogenase. The effects of pH on the midpoint potentials of these chloroplast proteins have been measured so that the effect of the light-induced increase in chloroplast stromal pH on the redox properties of the proteins can be calculated. Spectroscopic measurements on FTR and on an N-ethylmaleimide-modified derivative of the enzyme have been used to elucidate the role of the [4Fe-4S] cluster of FTR during the reduction of the enzyme's active-site disulfide by ferredoxin.

  • Characterization of the Ternary Complex Formed by Ferredoxin: Thioredoxin Reductase, Ferredoxin and Thioredoxin
    Photosynthesis. Energy from the Sun, 2008
    Co-Authors: Marcellus Ubbink, Peter Schürmann, Masakazu Hirasawa, Sung-kun Kim, Jatindra N. Tripathy, David Knaff
    Abstract:

    Ferredoxin:Thioredoxin reductase (FTR), catalyzes the two-electron reduction of Thioredoxins in chloroplasts and cyanobacteria, using reduced ferredoxin as the electron donor. Reduced Thioredoxins then play important roles in redox regulation. FTR, a heterodimer with a unique [4Fe-4S] cluster as its sole prosthetic group, has a single binding site for ferredoxin and a separate single binding site for Thioredoxin. NMR spectroscopy was used to map the binding site on ferredoxin for FTR in a 1:1 complex of the two proteins. A mono-gallium analog of this [2Fe- 2S] ferredoxin was obtained by reconstituting apo-ferredoxin in a gallium-containing refolding buffer. The use of this diamagnetic Ga structural analog eliminates the paramagnetic broadening of NMR resonances of amino acids in the vicinity of the [2Fe-2S] cluster in native ferredoxin. This has allowed the first complete mapping of the interaction interface of a [2Fe-2S] ferredoxin for a target enzyme. NMR spectroscopy was also used to map the interaction domain for FTR on Thioredoxin m in a 1:1 complex of the two proteins. Both similarities and differences are seen in the Thioredoxin m interaction domain for FTR in the non-covalent complex examined by NMR and in a disulfide-linked covalent complex of FTR and Thioredoxin m for which an X-ray crystal structure has been obtained. NMR has also been used to characterize a ternary complex between ferredoxin, FTR and Thioredoxin m in solution, confirming the presence of separate binding sites on FTR for its two substrates.

  • An atypical catalytic mechanism involving three cysteines of Thioredoxin
    Journal of Biological Chemistry, 2008
    Co-Authors: Cha San Koh, David Knaff, Jean-pierre Jacquot, Nicolas Rouhier, Nicolas Navrot, Masakazu Hirasawa, Gunnar Wingsle, Claude Didierjean, Razip Samian, Catherine Corbier
    Abstract:

    Unlike other Thioredoxins h characterized so far, a poplar Thioredoxin of the h type, PtTrxh4, is reduced by glutathione and glutaredoxin (Grx) but not NADPH:Thioredoxin reductase (NTR). PtTrxh4 contains three cysteines: one localized in an N-terminal extension (Cys4) and two (Cys58 and Cys61) in the classical Thioredoxin active site (57WCGPC61). The property of a mutant in which Cys58 was replaced by serine demonstrates that it is responsible for the initial nucleophilic attack during the catalytic cycle. The observation that the C4S mutant is inactive in the presence of Grx but fully active when dithiothreitol is used as a reductant indicates that Cys4 is required for the regeneration of PtTrxh4 by Grx. Biochemical and x-ray crystallographic studies indicate that two intramolecular disulfide bonds involving Cys58 can be formed, linking it to either Cys61 or Cys4. We propose thus a four-step disulfide cascade mechanism involving the transient glutathionylation of Cys4 to convert this atypical Thioredoxin h back to its active reduced form.

  • Cytosolic, Mitochondrial Thioredoxins and Thioredoxin Reductases in Arabidopsis Thaliana
    Photosynthesis Research, 2004
    Co-Authors: Claire Bréhélin, Christophe Laloi, Aaron Setterdahl, David Knaff, Yves Meyer
    Abstract:

    Thioredoxins, by reducing disulfide bridges are one of the main participants that regulate cellular redox balance. In plants, the Thioredoxin system is particularly complex. The most well-known Thioredoxins are the chloroplastic ones, that participate in the regulation of enzymatic activities during the transition between light and dark phases. The mitochondrial system composed of NADPH-dependent Thioredoxin reductase and type o Thioredoxin has only recently been described. The type h Thioredoxin group is better known. Yeast complementation experiments demonstrated that Arabidopsis thaliana Thioredoxins h have divergent functions, at least in Saccharomyces cerevisiae. They have diverse affinities for different target proteins, most probably because of structural differences. However, plant Thioredoxin h functions still have to be defined. Abbreviations: mBBr-monobromobimane; NADPH-nicotinamide adenine dinucleotide; NTR-NADPH Thioredoxin reductase

  • Cytosolic, mitochondrial Thioredoxins and Thioredoxin reductases in Arabidopsis thaliana.
    Photosynthesis research, 2004
    Co-Authors: Claire Bréhélin, Christophe Laloi, Aaron Setterdahl, David Knaff, Yves Meyer
    Abstract:

    Thioredoxins, by reducing disulfide bridges are one of the main participants that regulate cellular redox balance. In plants, the Thioredoxin system is particularly complex. The most well-known Thioredoxins are the chloroplastic ones, that participate in the regulation of enzymatic activities during the transition between light and dark phases. The mitochondrial system composed of NADPH-dependent Thioredoxin reductase and type o Thioredoxin has only recently been described. The type h Thioredoxin group is better known. Yeast complementation experiments demonstrated that Arabidopsis thaliana Thioredoxins h have divergent functions, at least in Saccharomyces cerevisiae. They have diverse affinities for different target proteins, most probably because of structural differences. However, plant Thioredoxin h functions still have to be defined.

Bob B. Buchanan - One of the best experts on this subject based on the ideXlab platform.

  • Seed Thioredoxin h
    Biochimica et biophysica acta, 2016
    Co-Authors: Per Hägglund, Bob B. Buchanan, Christine Finnie, Hiroyuki Yano, Azar Shahpiri, A. Henriksen, Birte Svensson
    Abstract:

    Thioredoxins are nearly ubiquitous disulfide reductases involved in a wide range of biochemical pathways in various biological systems, and also implicated in numerous biotechnological applications. Plants uniquely synthesize an array of Thioredoxins targeted to different cell compartments, for example chloroplastic f- and m-type Thioredoxins involved in regulation of the Calvin-Benson cycle. The cytosolic h-type Thioredoxins act as key regulators of seed germination and are recycled by NADPH-dependent Thioredoxin reductase. The present review on Thioredoxin h systems in plant seeds focuses on occurrence, reaction mechanisms, specificity, target protein identification, three-dimensional structure and various applications. The aim is to provide a general background as well as an update covering the most recent findings. This article is part of a Special Issue entitled: Plant Proteomics--a bridge between fundamental processes and crop production, edited by Dr. Hans-Peter Mock.

  • Redox Regulation: A Broadening Horizon
    Annual Review of Plant Biology, 2005
    Co-Authors: Bob B. Buchanan, Yves Balmer
    Abstract:

    Initially discovered in the context of photosynthesis, regulation by change in the redox state of thiol groups (S−S ↔ 2SH) is now known to occur throughout biology. Several systems, each linking a hydrogen donor to an intermediary disulfide protein, act to effect changes that alter the activity of target proteins: the ferredoxin/Thioredoxina small protein, reduced enzymatically by NADPH or ferredoxin, that is active in thiol/disulfide exchange and results in regulation or substrate conversion system, comprised of reduced ferredoxin, a Thioredoxin, and the enzyme, ferredoxin-Thioredoxin reductase; the NADP/Thioredoxin system, including NADPH, a Thioredoxin, and NADP-Thioredoxin reductase; and the glutathione/glutaredoxina small protein, reduced by glutathione, that is active in thiol/disulfide exchange and results in regulation or substrate conversion system, composed of reduced glutathione and a glutaredoxin. A related disulfide protein, protein disulfide isomerase (PDI) acts in protein assembly. Regulati...

  • [43] Ferredoxin/Thioredoxin system
    Methods in Enzymology, 2004
    Co-Authors: Nancy A. Crawford, Michel Droux, D E Carlson, Bob B. Buchanan
    Abstract:

    Publisher Summary This chapter focuses on the ferredoxin/Thioredoxin system. Light regulates enzymes of oxygenic photosynthesis via several mechanisms. Important among these is the ferredoxin/Thioredoxin system, an enzyme-mediated regulatory mechanism involving ferredoxin, ferredoxin-Thioredoxin reductase (FTR), and a Thioredoxin. Thioredoxins are proteins, typically of 12,000 molecular weight, that are widely, if not universally, distributed in the animal, plant, and bacterial kingdoms. Thioredoxins undergo reversible reduction and oxidation through changes in thiol groups. In the ferredoxin/Thioredoxin system, a Thioredoxin (Td) is reduced by photoreduced ferredoxin (Fd) via FTR, an iron-sulfur protein. Thioredoxins can also be chemically reduced in vitro in the dark by the nonphysiological reagent. Thioredoxin m is assayed by measuring its capacity to promote the reductive activation of NADP-MDH. The principle behind the Thioredoxin f assay is the same as in the Thioredoxin m assay described. Here, any of the known target enzymes of Thioredoxin f could be used to measure its capacity for reductive activation either with DTT or light, thylakoid membranes, and components of the ferredoxin/Thioredoxin system.

  • proteomics gives insight into the regulatory function of chloroplast Thioredoxins
    Proceedings of the National Academy of Sciences of the United States of America, 2003
    Co-Authors: Yves Balmer, Peter Schürmann, Antonius Koller, Wanda Manieri, Bob B. Buchanan
    Abstract:

    Thioredoxins are small multifunctional redox active proteins widely if not universally distributed among living organisms. In chloroplasts, two types of Thioredoxins (f and m) coexist and play central roles in regulating enzyme activity. Reduction of Thioredoxins in chloroplasts is catalyzed by an iron-sulfur disulfide enzyme, ferredoxin-Thioredoxin reductase, that receives photosynthetic electrons from ferredoxin, thereby providing a link between light and enzyme activity. Chloroplast Thioredoxins function in the regulation of the Calvin cycle and associated processes. However, the relatively small number of known Thioredoxin-linked proteins (about 16) raised the possibility that others remain to be identified. To pursue this opportunity, we have mutated Thioredoxins f and m, such that the buried cysteine of the active disulfide has been replaced by serine or alanine, and bound them to affinity columns to trap target proteins of chloroplast stroma. The covalently linked proteins were eluted with DTT, separated on gels, and identified by mass spectrometry. This approach led to the identification of 15 potential targets that function in 10 chloroplast processes not known to be Thioredoxin linked. Included are proteins that seem to function in plastid-to-nucleus signaling and in a previously unrecognized type of oxidative regulation. Approximately two-thirds of these targets contained conserved cysteines. We also identified 11 previously unknown and 9 confirmed target proteins that are members of pathways known to be regulated by Thioredoxin. In contrast to results with individual enzyme assays, specificity for Thioredoxin f or m was not observed on affinity chromatography.

  • Yet another plant Thioredoxin.
    Trends in plant science, 2002
    Co-Authors: Yves Balmer, Bob B. Buchanan
    Abstract:

    Thioredoxins are widely distributed proteins that function in a broad spectrum of cellular reactions. Plant cells have well characterized chloroplast and cytosolic Thioredoxin systems, but, unlike animals and yeast, a mitochondrial counterpart has not been clearly defined. Recently, a complete Thioredoxin system has been described in plant mitochondria, opening a new door for the study of Thioredoxins as well as mitochondria.

Claire Bréhélin - One of the best experts on this subject based on the ideXlab platform.

  • Cytosolic, Mitochondrial Thioredoxins and Thioredoxin Reductases in Arabidopsis Thaliana
    Photosynthesis Research, 2004
    Co-Authors: Claire Bréhélin, Christophe Laloi, Aaron Setterdahl, David Knaff, Yves Meyer
    Abstract:

    Thioredoxins, by reducing disulfide bridges are one of the main participants that regulate cellular redox balance. In plants, the Thioredoxin system is particularly complex. The most well-known Thioredoxins are the chloroplastic ones, that participate in the regulation of enzymatic activities during the transition between light and dark phases. The mitochondrial system composed of NADPH-dependent Thioredoxin reductase and type o Thioredoxin has only recently been described. The type h Thioredoxin group is better known. Yeast complementation experiments demonstrated that Arabidopsis thaliana Thioredoxins h have divergent functions, at least in Saccharomyces cerevisiae. They have diverse affinities for different target proteins, most probably because of structural differences. However, plant Thioredoxin h functions still have to be defined. Abbreviations: mBBr-monobromobimane; NADPH-nicotinamide adenine dinucleotide; NTR-NADPH Thioredoxin reductase

  • Cytosolic, mitochondrial Thioredoxins and Thioredoxin reductases in Arabidopsis thaliana.
    Photosynthesis research, 2004
    Co-Authors: Claire Bréhélin, Christophe Laloi, Aaron Setterdahl, David Knaff, Yves Meyer
    Abstract:

    Thioredoxins, by reducing disulfide bridges are one of the main participants that regulate cellular redox balance. In plants, the Thioredoxin system is particularly complex. The most well-known Thioredoxins are the chloroplastic ones, that participate in the regulation of enzymatic activities during the transition between light and dark phases. The mitochondrial system composed of NADPH-dependent Thioredoxin reductase and type o Thioredoxin has only recently been described. The type h Thioredoxin group is better known. Yeast complementation experiments demonstrated that Arabidopsis thaliana Thioredoxins h have divergent functions, at least in Saccharomyces cerevisiae. They have diverse affinities for different target proteins, most probably because of structural differences. However, plant Thioredoxin h functions still have to be defined.

  • Characterization of Determinants for the Specificity of Arabidopsis Thioredoxins h in Yeast Complementation
    Journal of Biological Chemistry, 2000
    Co-Authors: Claire Bréhélin, Nabil Mouaheb, Lionel Verdoucq, Jean-marc Lancelin, Yves Meyer
    Abstract:

    The disruption of the two Thioredoxin genes in Sac-charomyces cerevisiae leads to a complex phenotype, including the inability to use methionine sulfoxide as sulfur source, modified cell cycle parameters, reduced H 2 O 2 tolerance, and inability to use sulfate as sulfur source. Expression of one of the multiple Arabidopsis thaliana Thioredoxins h in this mutant complements only some aspects of the phenotype, depending on the expressed Thioredoxin: AtTRX2 or AtTRX3 induce me-thionine sulfoxide assimilation and restore a normal cell cycle. In addition AtTRX2 also confers growth on sulfate but no H 2 O 2 tolerance. In contrast, AtTRX3 does not confer growth on sulfate but induces H 2 O 2 tolerance. We have constructed hybrid proteins between these two Thioredoxins and show that all information necessary for sulfate assimilation is present in the C-terminal part of AtTRX2, whereas some information needed for H 2 O 2 tolerance is located in the N-terminal part of AtTRX3. In addition, mutation of the atypical redox active site WCPPC to the classical site WCGPC restores some growth on sulfate. All these data suggest that the multiple Arabidopsis Thioredoxins h originate from a totipo-tent ancestor with all the determinants necessary for interaction with the different Thioredoxin target proteins. After duplications each member evolved by losing or masking some of the determinants.