Thioredoxin reductase Trr1 (synonym caf4; EC 1.8.1.9) of Schizosaccharomyces pombe, an FAD-containing, NADPH-dependent homodimeric flavoenzyme of the low-molecular-weight (class-II pyridine nucleotide-disulfide oxidoreductase) thioredoxin reductase family. It is encoded by the only thioredoxin reductase gene in the genome and reduces oxidised thioredoxin, which in turn supplies electrons to thioredoxin-dependent enzymes such as the peroxiredoxin Tpx1 (the H2O2 scavenger and sensor upstream of Pap1). Trr1 is cytosolic (also detected in the nucleus). Increased dosage raises TrxR activity and tolerance of mercury and aluminium salts, and trr1 promoter activity is induced by menadione, mercuric chloride, H2O2, aluminium chloride and selenite, the menadione and mercury responses being Pap1-mediated. Whether the single S. pombe enzyme also serves the mitochondrial thioredoxin Trx2 is not established.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004791 thioredoxin-disulfide reductase (NADPH) activity | IBA GO_REF:0000033 | ACCEPT | Summary: PANTHER PTN005133404 IBA (donors include S. cerevisiae TRR1/TRR2, E. coli TrxB and plant NTRs); Trr1 is a canonical low-Mr thioredoxin reductase with the CxxC redox-active disulfide. Supporting Evidence: file:SCHPO/trr1/trr1-uniprot.txt Reaction=[thioredoxin]-dithiol + NADP(+) = [thioredoxin]-disulfide + PMID:15135546 The S. pombe cells harboring the cloned TrxR gene contain increased TrxR activity, and shows higher survivals on solid media with mercuric chloride or aluminum chloride. |
| GO:0004791 thioredoxin-disulfide reductase (NADPH) activity | IDA PMID:17409354 The peroxiredoxin Tpx1 is essential as a H2O2 scavenger duri... | ACCEPT | Summary: IDA from Jara et al. (Tpx1 study). The cached abstract does not mention Trr1; the annotation presumably derives from a thioredoxin-coupled peroxidase assay in the full text, which the PomBase curator read. The activity is consistent with all other evidence, so the curator is followed. Supporting Evidence: PMID:17409354 The two-cysteine peroxiredoxin Tpx1 of Schizosaccharomyces pombe has been characterized as the H(2)O(2) sensor that transduces the redox signal to the transcription factor Pap1. file:SCHPO/trr1/trr1-uniprot.txt Reaction=[thioredoxin]-dithiol + NADP(+) = [thioredoxin]-disulfide + |
| GO:0004791 thioredoxin-disulfide reductase (NADPH) activity | IEA GO_REF:0000120 | ACCEPT | Summary: Combined IEA (ARBA, IPR005982, RHEA:20345, EC 1.8.1.9); correct. Supporting Evidence: file:SCHPO/trr1/trr1-uniprot.txt Reaction=[thioredoxin]-dithiol + NADP(+) = [thioredoxin]-disulfide + |
| GO:0004791 thioredoxin-disulfide reductase (NADPH) activity | IMP PMID:15135546 Stress-dependent regulation of the gene encoding thioredoxin... | ACCEPT | Summary: Hong et al. showed that cells carrying the cloned trr1 gene have increased TrxR activity (a gene-dosage rather than loss-of-function experiment, but directly linking the gene to the activity). Supporting Evidence: PMID:15135546 The S. pombe cells harboring the cloned TrxR gene contain increased TrxR activity, and shows higher survivals on solid media with mercuric chloride or aluminum chloride. |
| GO:0005515 protein binding | IPI PMID:17409354 The peroxiredoxin Tpx1 is essential as a H2O2 scavenger duri... | REMOVE | Summary: IPI with Tpx1 (SPAC7D4.07c) from the Tpx1 study. An association of Trr1 with its downstream peroxiredoxin is plausible within the Trr1-Trx1-Tpx1 electron relay, but "protein binding" conveys nothing about Trr1 function, and the cached abstract does not describe the interaction. Removed under the protein-binding policy (uninformative term); this does not imply the interaction is false, and an informative term could be considered if the full text shows a specific activity. Supporting Evidence: PMID:17409354 The two-cysteine peroxiredoxin Tpx1 of Schizosaccharomyces pombe has been characterized as the H(2)O(2) sensor that transduces the redox signal to the transcription factor Pap1. |
| GO:0005634 nucleus | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | KEEP AS NON CORE | Summary: ORFeome YFP survey also detected Trr1 in the nucleus; a soluble cytosolic enzyme may enter the nucleus, and nuclear thioredoxin targets exist, but no nuclear role is shown. Supporting Evidence: PMID:16823372 we determined the localization of 4,431 proteins, corresponding to approximately 90% of the fission yeast proteome, by tagging each ORF with the yellow fluorescent protein |
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | ACCEPT | Summary: Combined IEA (IPR005982, UniProt SubCell Cytoplasm); correct. Supporting Evidence: file:SCHPO/trr1/trr1-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm {ECO:0000250|UniProtKB:P29509}. |
| GO:0005737 cytoplasm | ISS GO_REF:0000024 | ACCEPT | Summary: ISS from S. cerevisiae TRR1 (P29509, cytoplasmic thioredoxin reductase); consistent with the S. pombe ORFeome cytosol HDA. Supporting Evidence: file:SCHPO/trr1/trr1-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm {ECO:0000250|UniProtKB:P29509}. |
| GO:0005739 mitochondrion | ISS GO_REF:0000024 | UNDECIDED | Summary: ISS from S. cerevisiae TRR2 (P38816), the mitochondrial paralog that S. pombe lacks. Because Trr1 is the only S. pombe thioredoxin reductase and S. pombe has a mitochondrial thioredoxin (Trx2), a mitochondrial pool is plausible, but Trr1 has no predicted presequence noted in UniProt and no S. pombe localization or activity data place it in mitochondria (the ORFeome study reports cytosol and nucleus). Transfer of location from a paralog with a dedicated targeting signal cannot be assessed without S. pombe data. Supporting Evidence: PMID:15135546 The unique putative gene for thioredoxin reductase (TrxR) was isolated from the chromosomal DNA of the fission yeast Schizosaccharomyces pombe. PMID:16823372 we determined the localization of 4,431 proteins, corresponding to approximately 90% of the fission yeast proteome, by tagging each ORF with the yellow fluorescent protein |
| GO:0005829 cytosol | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | ACCEPT | Summary: ORFeome YFP localization to the cytosol; matches the cytosolic thioredoxin system. Supporting Evidence: PMID:16823372 we determined the localization of 4,431 proteins, corresponding to approximately 90% of the fission yeast proteome, by tagging each ORF with the yellow fluorescent protein |
| GO:0005829 cytosol | IBA GO_REF:0000033 | ACCEPT | Summary: PANTHER IBA for cytosol (donors S. cerevisiae TRR1, C. albicans TRR1); correct. Supporting Evidence: PMID:16823372 we determined the localization of 4,431 proteins, corresponding to approximately 90% of the fission yeast proteome, by tagging each ORF with the yellow fluorescent protein |
| GO:0016491 oxidoreductase activity | IEA GO_REF:0000002 | MODIFY | Summary: Generic oxidoreductase activity from InterPro FAD/NAD(P)-binding domain entries; replace with the specific thioredoxin-disulfide reductase activity. Proposed replacements: thioredoxin-disulfide reductase (NADPH) activity Supporting Evidence: file:SCHPO/trr1/trr1-uniprot.txt Reaction=[thioredoxin]-dithiol + NADP(+) = [thioredoxin]-disulfide + |
| GO:0019430 removal of superoxide radicals | IEA GO_REF:0000002 | REMOVE | Summary: InterPro2GO from IPR005982 (thioredoxin reductase) to removal of superoxide radicals. Thioredoxin reductase does not act on superoxide; it reduces thioredoxin, which supports peroxide-reducing peroxiredoxins. The mapping is not appropriate for this protein (same call as S. cerevisiae TRR1). Supporting Evidence: file:SCHPO/trr1/trr1-uniprot.txt Reaction=[thioredoxin]-dithiol + NADP(+) = [thioredoxin]-disulfide + |
| GO:0045454 cell redox homeostasis | IBA GO_REF:0000033 | ACCEPT | Summary: PANTHER IBA; the thioredoxin system is a principal maintainer of cellular thiol-redox state. Correct core process. Supporting Evidence: file:SCHPO/trr1/trr1-uniprot.txt Reaction=[thioredoxin]-dithiol + NADP(+) = [thioredoxin]-disulfide + PMID:15135546 These results suggest that the S. pombe TrxR gene is one of the stress response-related genes. |
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Download this section (compressed HTML)Q: S. pombe has a single thioredoxin reductase but a mitochondrial thioredoxin (Trx2): what reduces Trx2 in mitochondria, a minor mitochondrial pool of Trr1 or another reductant?
Experiment: Fractionate mitochondria from a strain expressing endogenously tagged Trr1 with protease protection; test Trx2 redox state (AMS shift) in a Trr1 depletion strain.
Hypothesis: A fraction of Trr1 is imported into mitochondria to reduce Trx2.
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