1.8.7.2: ferredoxin:thioredoxin reductase
This is an abbreviated version!
For detailed information about ferredoxin:thioredoxin reductase, go to the full flat file.
Word Map on EC 1.8.7.2
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1.8.7.2
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thioredoxins
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chloroplast
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spinach
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redox-active
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reductases
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epr
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fe-s
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light-dependent
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one-electron-reduced
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two-electron
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iron-sulfur
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raman
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one-electron
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variable-temperature
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heterodisulfide
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dithiol
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methanosarcina
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synthesis
- 1.8.7.2
- thioredoxins
- chloroplast
- spinach
-
redox-active
- reductases
- epr
- fe-s
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light-dependent
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one-electron-reduced
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two-electron
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iron-sulfur
-
raman
-
one-electron
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variable-temperature
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heterodisulfide
- dithiol
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methanosarcina
- synthesis
Reaction
2 reduced ferredoxin + = 2 oxidized ferredoxin + + 2 H+
Synonyms
Fd-thioredoxin reductase, Fd:TRX reductase, FdR, Fdx flavin-thioredoxin reductase, Fdx-dependent thioredoxin reductase, FDX-dependent TRX reductase, ferredoxin disulfide reductase, ferredoxin-dependent thioredoxin reductase, ferredoxin-thioredoxin reductase, FFTR, FTR, FTRc, glr0719, GvDTR, iron-sulfur ferredoxin-dependent thioredoxin reductase, Ma_1659, protein modulase
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General Information
General Information on EC 1.8.7.2 - ferredoxin:thioredoxin reductase
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evolution
malfunction
metabolism
physiological function
additional information
some cyanobacteria, such as the thylakoid-less Gloeobacter and the ocean-dwelling green oxyphotobacterium Prochlorococcus, lack thioredoxin reductase flavoenzyme (NTR) and (Fdx)-dependent thioredoxin reductase (FTR) but contain a thioredoxin reductase flavoenzyme (formerly tentatively called deeply-rooted thioredoxin reductase or DTR), whose electron donor is Fdx. This cyanobacterial enzyme belongs to the Fdx flavin-thioredoxin reductase (FFTR) family, originally described in the anaerobic bacterium Clostridium pasteurianum. Accordingly, the enzyme hitherto termed DTR is renamed FFTR. The FFTR is spread within the cyanobacteria phylum. By substituting for FTR, it connects the reduction of target proteins to photosynthesis. FFTR acquisition constitutes a mechanism of evolutionary adaptation in marine phytoplankton such as Prochlorococcus that live in low-iron environments. Cyanobacterial Fdx-dependent thioredoxin reductases might have diverged early in the evolution into flavo- or metalloenzymes
evolution
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some cyanobacteria, such as the thylakoid-less Gloeobacter and the ocean-dwelling green oxyphotobacterium Prochlorococcus, lack thioredoxin reductase flavoenzyme (NTR) and (Fdx)-dependent thioredoxin reductase (FTR) but contain a thioredoxin reductase flavoenzyme (formerly tentatively called deeply-rooted thioredoxin reductase or DTR), whose electron donor is Fdx. This cyanobacterial enzyme belongs to the Fdx flavin-thioredoxin reductase (FFTR) family, originally described in the anaerobic bacterium Clostridium pasteurianum. Accordingly, the enzyme hitherto termed DTR is renamed FFTR. The FFTR is spread within the cyanobacteria phylum. By substituting for FTR, it connects the reduction of target proteins to photosynthesis. FFTR acquisition constitutes a mechanism of evolutionary adaptation in marine phytoplankton such as Prochlorococcus that live in low-iron environments. Cyanobacterial Fdx-dependent thioredoxin reductases might have diverged early in the evolution into flavo- or metalloenzymes
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Arabidopsis thaliana mutants with decreased contents of the catalytic subunit of FTR (FTRc), hence with impaired fuel of electrons into the pathway, show severe chlorosis in leaf sectors near the petiole, similar to the phenotype of mutant plants with lower FTR activity. In contrast, the deficiency of individual TRXs has low effect on growth phenotype indicating functional redundancy of the different plastid TRXs, except TRX z since mutants lacking this TRX show an albino phenotype
malfunction
deletion of the C-terminal tail does not significantly affect structure and both GvDTR and GvDTR_DELTAtail proteins are properly folded. The mutant enzyme is able to reduce Trx when a non-physiological electron donor (dithionite) is used
malfunction
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deletion of the C-terminal tail does not significantly affect structure and both GvDTR and GvDTR_DELTAtail proteins are properly folded. The mutant enzyme is able to reduce Trx when a non-physiological electron donor (dithionite) is used
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the FDX-FTR-TRXs pathway allows the regulation of redox-sensitive chloroplast enzymes in response to light. In addition, chloroplasts contain an NADPH-dependent redox system, termed NTRC, which allows the use of NADPH in the redox network of these organelles. NTRC is required for the activity of TRXs. Genetic approaches using mutants of Arabidopsis thaliana in combination with biochemical and physiological studies show that both redox systems, NTRC and FDX-FTR-TRXs, participate in fine-tuning chloroplast performance in response to changes in light intensity. Moreover, these studies reveal the participation of 2-Cys peroxiredoxin (2-Cys PRX), a thiol-dependent peroxidase, in the control of the reducing activity of chloroplast TRXs as well as in the rapid oxidation of stromal enzymes upon darkness. Analysis of functional relationship of 2-Cys PRXs with NTRC and the FDX-FTR-TRXs redox systems for fine-tuning chloroplast performance in response to changes in light intensity and darkness, overview. NTRC and FDX-FTR-TRXs pathway are integrated by the redox balance of 2-Cys PRXs. Redox regulation is an additional layer of control of the signaling function of the chloroplast
metabolism
thiol-based redox regulation is a mechanism for controlling metabolic pathways in chloroplasts. Thioredoxin (Trx) possesses a pair of redox-active cysteines that activates specific enzymes in a light-dependent manner. The redox level of Trx is maintained by ferredoxin-Trx reductase (FTR) and ferredoxin (Fd), the latter being the final electron acceptor in the photosynthetic electron transport chain. In this Fd/Trx cascade, electrons are sequentially transmitted from photosystem I, via Fd, FTR, and Trx, to target enzymes such as fructose-1,6-bisphosphatase, sedoheptulose-bisphosphatase, NADP-malate dehydrogenase, or 2-Cys peroxiredoxins
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ferredoxin-thioredoxin reductase is the first member of a thiol chain that links light to enzyme regulation. FTR possesses a catalytically active dithiol group localized on the 13 kDa subunit, that occurs in all species investigated and accepts reducing equivalents from photoreduced ferredoxin and transfers them stoichiometrically to the disulfide form of thioredoxin m. The reduced thioredoxin m, in turn, reduces NADP-malate dehydrogenase, thereby converting it from an inactive disulfide to an active thiol form
physiological function
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identification of ferredoxin-thioredoxin reductase and NADPH-thioredoxin reductase, and four typical thioredoxin isoforms identified by genomic analysis. The NADPH-thioredoxin reductase pathway is important for the antioxidant system, whereas the ferredoxin-thioredoxin reductase pathway may play a more important role in the control of cell growth rate. The gene product of slr0623, the homolog of m-type thioredoxin in higher plants, is the most abundant thioredoxin, and accumulation of thioredoxin isoforms occurs dependent on the expression of the other redox-related proteins
physiological function
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study on mutant lines in which one of two genes encoding FTRA variable subunit is disrupted by T-DNA insertion. In FTRA1mutants, the absence of the corresponding transcript is not compensated by the increase in the level of FTRA2 mRNA. Mutant plants exhibit phenotypic perturbations when compared with wild-type plants. Disruptants are significantly more sensitive to oxidative stress as imposed under high light or in the presence of paraquat. In the leaves of mutants placed under normal culture conditions, NADP-dependent malate dehydrogenase activation rate is abnormally low. A partially compensating increase of the enzyme activity is found as well as a higher amount of 2-cysperoxiredoxin
physiological function
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virus-induced gene silencing of the catalytic subunit FTR-c results in necrotic lesions with typical cell death symptoms and reactive oxygen species production in tomato leaves. These FTR-c-silenced plants display enhanced disease resistance against bacterial pathogens, specifically Pseudomonas syringae pv. tomato DC3000, by the induction of defense-related genes such as PR-1, PR-2, PR-5, GlucA, Chi3, and Chi9
physiological function
ferredoxin:thioredoxin reductase is the key enzyme of the ferredoxid-thioredoxin system, and is involved in the light regulation of carbon metabolism in oxygenic photosynthesis catalyzing the reduction of thioredoxins with light-generated electrons
physiological function
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the enzyme is required for proper chloroplast development and is involved in the regulation of plastid gene expression. The enzyme and thopredoxin z act together in the regulation of plastid-encoded RNA polymerase function during early stages of chloroplast development
physiological function
photosynthetic electron transport occurs on the thylakoid membrane of chloroplasts. Ferredoxin (Fd), the final acceptor in the electron transport chain, distributes electrons to several Fd-dependent enzymes including Fd-thioredoxin reductase (FTR). A cascade from Fd to FTR further reduces thioredoxin (Trx), which tunes the activity of target metabolic enzymes eventually in a light-dependent manner
physiological function
regulation of enzyme activity based on thiol-disulfide exchange is a regulatory mechanism in which the protein disulfide reductase activity of thioredoxins (TRXs) plays a central role. Plant chloroplasts are equipped with a complex set of up to 20 TRXs and TRX-like proteins, the activity of which is supported by reducing power provided by photosynthetically reduced ferredoxin (FDX) with the participation of a FDX-dependent TRX reductase (FTR). The complex redox network composed of the FDX-FTR-TRXs pathway links redox regulation to light. Therefore, the FDX-FTR-TRXs pathway allows the regulation of redox-sensitive chloroplast enzymes in response to light. Involvement of redox regulation in chloroplast retrograde signaling modulates early stages of plant development and response to environmental stress, overview. Ferredoxin, FDX, the final acceptor of the photosynthetic electron transport chain, fuels reducing equivalents to plastid thioredoxins (TRXs) with the participation of FTR
physiological function
thioredoxin reductases control the redox state of thioredoxins (Trxs), ubiquitous proteins that regulate a spectrum of enzymes by dithiol-disulfide exchange reactions. In most organisms, Trx is reduced by NADPH via a thioredoxin reductase flavoenzyme (NTR), but in oxygenic photosynthetic organisms, this function can also be performed by an iron-sulfur ferredoxin (Fdx)-dependent thioredoxin reductase (FTR) that links light to metabolic regulation. The FFTR/Trx system of Gloeobacter is able to reduce CP12, a small protein functional in the regulation of two enzymes of the Calvin-Benson cycle in oxygenic photosynthetic organisms-phosphoribulokinase and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). FFTR can substitute for FTR in light-linked redox regulation in Gloeobacter
physiological function
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thioredoxin reductases control the redox state of thioredoxins (Trxs), ubiquitous proteins that regulate a spectrum of enzymes by dithiol-disulfide exchange reactions. In most organisms, Trx is reduced by NADPH via a thioredoxin reductase flavoenzyme (NTR), but in oxygenic photosynthetic organisms, this function can also be performed by an iron-sulfur ferredoxin (Fdx)-dependent thioredoxin reductase (FTR) that links light to metabolic regulation. The FFTR/Trx system of Gloeobacter is able to reduce CP12, a small protein functional in the regulation of two enzymes of the Calvin-Benson cycle in oxygenic photosynthetic organisms-phosphoribulokinase and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). FFTR can substitute for FTR in light-linked redox regulation in Gloeobacter
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role for Fe-S clusters in the enzyme mechanism involving both the stabilization of a thiyl radical intermediate and cluster site-specific chemistry involving a bridging sulfide
additional information
crystallographic structure of the transient complex between the plant-type Fdx1 and the thioredoxin reductase flavoenzyme from Gloeobacter violaceus. A unique feature of GvDTR is the presence of a C-terminal tail with a conserved aromatic amino acid that stacks onto the isoalloxazine ring of the FAD of the adjacent monomer. GvFdx1 binding to GvDTR is strictly dependent on the presence of the enzyme's C-terminal tail. Conformations adopted by GvDTR during its catalytic cycle, detailed overview
additional information
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crystallographic structure of the transient complex between the plant-type Fdx1 and the thioredoxin reductase flavoenzyme from Gloeobacter violaceus. A unique feature of GvDTR is the presence of a C-terminal tail with a conserved aromatic amino acid that stacks onto the isoalloxazine ring of the FAD of the adjacent monomer. GvFdx1 binding to GvDTR is strictly dependent on the presence of the enzyme's C-terminal tail. Conformations adopted by GvDTR during its catalytic cycle, detailed overview
additional information
superposition of the FTR structure with/without Trx showed no main chain structural changes upon complex formation. There is no significant conformational change for single and complexed Trx-m structures. Nonetheless, the interface of FTR:Trx complexes displayed significant variation. Comparative analysis of the three structures shows two types of intermolecular interactions: (i) common interactions shared by all three complexes and (ii) isoform-specific interactions, which might be important for fine-tuning FTR:Trx activity
additional information
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superposition of the FTR structure with/without Trx showed no main chain structural changes upon complex formation. There is no significant conformational change for single and complexed Trx-m structures. Nonetheless, the interface of FTR:Trx complexes displayed significant variation. Comparative analysis of the three structures shows two types of intermolecular interactions: (i) common interactions shared by all three complexes and (ii) isoform-specific interactions, which might be important for fine-tuning FTR:Trx activity
additional information
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crystallographic structure of the transient complex between the plant-type Fdx1 and the thioredoxin reductase flavoenzyme from Gloeobacter violaceus. A unique feature of GvDTR is the presence of a C-terminal tail with a conserved aromatic amino acid that stacks onto the isoalloxazine ring of the FAD of the adjacent monomer. GvFdx1 binding to GvDTR is strictly dependent on the presence of the enzyme's C-terminal tail. Conformations adopted by GvDTR during its catalytic cycle, detailed overview
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