EC Number   |
General Information |
Reference |
|---|
   1.8.7.2 | evolution |
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 |
-, 765599 |
| 1.8.7.2 | malfunction |
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 |
765600 |
| 1.8.7.2 | 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 |
-, 765599 |
| 1.8.7.2 | metabolism |
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 |
765600 |
| 1.8.7.2 | 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 |
765730 |
| 1.8.7.2 | more |
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 |
-, 765599 |
| 1.8.7.2 | more |
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 |
702192 |
| 1.8.7.2 | more |
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 |
765730 |
| 1.8.7.2 | physiological function |
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 |
701891 |
| 1.8.7.2 | 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 |
703527 |
