Grx2 (YDR513W) is the major dithiol (CPYC) glutaredoxin of Saccharomyces cerevisiae, accounting for most cellular heat-stable glutathione-dependent disulfide oxidoreductase activity. It reduces protein disulfides and glutathione-mixed disulfides using GSH (recycled by Glr1/NADPH), and can reduce GSSG with dihydrolipoamide, serving as a backup to glutathione reductase for cytosolic GSSG reduction. Two isoforms arise from alternative in-frame AUGs: a long isoform with a mitochondrial presequence imported into the matrix (with unprocessed form on the outer membrane) and a short cytosolic isoform. Grx2 also shows glutathione peroxidase-like and glutathione S-transferase activities, has ~15-fold higher specific activity and lower Km for GSH than its paralog Grx1, and grx2 mutants are sensitive to hydrogen peroxide. Redox proteomics identified about forty proteins whose cysteine redox state depends on Grx2 or its location, and Grx2 mediates reversible S-glutathionylation of Cys56 of the DHBP synthase Rib3 in vitro.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004364 glutathione transferase activity | IDA PMID:12684511 Role of yeast glutaredoxins as glutathione S-transferases. | KEEP AS NON CORE | Summary: Collinson & Grant (abstract-only cache) showed purified Grx2 has CDNB GST activity, and grx1 grx2 gtt1 gtt2 strains lose most cellular GST activity. Genuine but secondary activity. Supporting Evidence: PMID:12684511 both Grx1 and Grx2 are shown be active as glutathione S-transferases (GSTs), and their activity with model substrates such as 1-chloro-2,4-dinitrobenzene is similar to their activity with hydroperoxides. |
| GO:0004364 glutathione transferase activity | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: ARBA/RHEA/EC 2.5.1.18 mapping from UniProt catalytic activity lines. Correct but secondary. Supporting Evidence: PMID:12684511 both Grx1 and Grx2 are shown be active as glutathione S-transferases (GSTs), and their activity with model substrates such as 1-chloro-2,4-dinitrobenzene is similar to their activity with hydroperoxides. |
| GO:0004602 glutathione peroxidase activity | EXP PMID:11875065 The yeast glutaredoxins are active as glutathione peroxidase... | KEEP AS NON CORE | Summary: Collinson et al. (abstract-only cache): glutaredoxins reduce hydroperoxides catalytically with GSH/Glr1/NADPH and GRX2 overexpression increases hydroperoxide resistance. Real secondary activity. Supporting Evidence: PMID:11875065 directly reduce hydroperoxides in a catalytic manner, using reducing power provided by NADPH, GSH, and glutathione reductase. PMID:11875065 Elevating the gene dosage of GRX1 or GRX2 increases resistance to hydroperoxides including hydrogen peroxide, tert-butyl hydroperoxide and cumene hydroperoxide. |
| GO:0004602 glutathione peroxidase activity | IDA PMID:12684511 Role of yeast glutaredoxins as glutathione S-transferases. | KEEP AS NON CORE | Summary: Grx2 shown to be a general hydroperoxidase (H2O2 > cumene > t-butyl hydroperoxide). Secondary activity. Supporting Evidence: PMID:12684511 We now show that Grx2 is also a general hydroperoxidase, and kinetic data indicate that both enzymes have a similar pattern of activity, which is highest with hydrogen peroxide, followed by cumene hydroperoxide and tert-butyl hydroperoxide. |
| GO:0004602 glutathione peroxidase activity | IDA PMID:18992757 Structural aspects of the distinct biochemical properties of... | KEEP AS NON CORE | Summary: Discola et al. (abstract-only cache) kinetic/structural comparison of Grx1 and Grx2; deferring to the curator on the peroxidase assay. Secondary activity. Supporting Evidence: PMID:18992757 yGrx2 has a specific activity 15 times higher than that of yGrx1 PMID:18992757 yGrx2 possesses a lower K(M) for glutathione and a higher turnover than yGrx1. |
| GO:0004602 glutathione peroxidase activity | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: RHEA:16833 / EC 1.11.1.9 mapping from UniProt. Correct but secondary. Supporting Evidence: PMID:12684511 We now show that Grx2 is also a general hydroperoxidase, and kinetic data indicate that both enzymes have a similar pattern of activity, which is highest with hydrogen peroxide, followed by cumene hydroperoxide and tert-butyl hydroperoxide. |
| GO:0005634 nucleus | HDA PMID:26928762 One library to make them all: streamlining the creation of y... | KEEP AS NON CORE | Summary: SWAT N-terminal GFP library screen recorded nuclear signal; an N-terminal tag would block the mitochondrial presequence, so the distribution reflects the cytosolic/nucleocytoplasmic form. No nuclear function known. Supporting Evidence: PMID:16606613 the cytosolic isoform of Grx2 was synthesized from the second AUG, lacking an N-terminal extension. |
| GO:0005634 nucleus | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: IBA from PTN000807735 (S. pombe grx1 donor); plausible nucleocytoplasmic distribution of the short isoform, non-core. Supporting Evidence: PMID:16606613 the cytosolic isoform of Grx2 was synthesized from the second AUG, lacking an N-terminal extension. |
| GO:0005737 cytoplasm | EXP PMID:11958675 Two isoforms of Saccharomyces cerevisiae glutaredoxin 2 are ... | ACCEPT | Summary: Pedrajas et al. detected the short Grx2 isoform in the cytosolic fraction. Supporting Evidence: PMID:11958675 it is shown that both isoforms are present in mitochondria, but only the short one is detected in the cytosolic fraction. |
| GO:0005737 cytoplasm | EXP PMID:16606613 One single in-frame AUG codon is responsible for a diversity... | ACCEPT | Summary: Porras et al. showed the cytosolic isoform is translated from the second in-frame AUG (Met35). Supporting Evidence: PMID:16606613 the cytosolic isoform of Grx2 was synthesized from the second AUG, lacking an N-terminal extension. |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from dithiol glutaredoxin clade; consistent with the cytosolic isoform. Supporting Evidence: file:yeast/GRX2/GRX2-uniprot.txt SUBCELLULAR LOCATION: [Isoform Cytoplasmic]: Cytoplasm |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt SubCell mapping for the cytoplasmic isoform. Supporting Evidence: file:yeast/GRX2/GRX2-uniprot.txt SUBCELLULAR LOCATION: [Isoform Cytoplasmic]: Cytoplasm |
| GO:0005739 mitochondrion | EXP PMID:16606613 One single in-frame AUG codon is responsible for a diversity... | ACCEPT | Summary: Porras et al.: translation from the first AUG yields a presequence-bearing long isoform imported into mitochondria (matrix; unprocessed form accumulates in outer membrane). Supporting Evidence: PMID:16606613 Translation from the first AUG resulted in a long isoform carrying a mitochondrial targeting presequence. PMID:16606613 Substitution of Met(35), the second translation start site, to Val resulted in an exclusive targeting to the mitochondrial matrix. |
| GO:0005739 mitochondrion | HDA PMID:14576278 The proteome of Saccharomyces cerevisiae mitochondria. | ACCEPT | Summary: Sickmann et al. mitochondrial proteome detected Grx2; consistent with the mitochondrial isoform. Supporting Evidence: file:yeast/GRX2/GRX2-uniprot.txt SUBCELLULAR LOCATION: [Isoform Mitochondrial]: Mitochondrion |
| GO:0005739 mitochondrion | HDA PMID:16823961 Toward the complete yeast mitochondrial proteome: multidimen... | ACCEPT | Summary: Reinders et al. mitochondrial proteomics detected Grx2; consistent with targeted isoform. Supporting Evidence: file:yeast/GRX2/GRX2-uniprot.txt SUBCELLULAR LOCATION: [Isoform Mitochondrial]: Mitochondrion |
| GO:0005739 mitochondrion | HDA PMID:24769239 Quantitative variations of the mitochondrial proteome and ph... | ACCEPT | Summary: Renvoise et al. quantitative mitochondrial proteome detected Grx2; consistent. Supporting Evidence: file:yeast/GRX2/GRX2-uniprot.txt SUBCELLULAR LOCATION: [Isoform Mitochondrial]: Mitochondrion |
| GO:0005739 mitochondrion | IDA PMID:11958675 Two isoforms of Saccharomyces cerevisiae glutaredoxin 2 are ... | ACCEPT | Summary: Pedrajas et al. immunodetected both Grx2 isoforms in purified mitochondria. Supporting Evidence: PMID:11958675 it is shown that both isoforms are present in mitochondria, but only the short one is detected in the cytosolic fraction. |
| GO:0005739 mitochondrion | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt SubCell mapping for the mitochondrial isoform. Supporting Evidence: file:yeast/GRX2/GRX2-uniprot.txt SUBCELLULAR LOCATION: [Isoform Mitochondrial]: Mitochondrion |
| GO:0005829 cytosol | IDA PMID:11958675 Two isoforms of Saccharomyces cerevisiae glutaredoxin 2 are ... | ACCEPT | Summary: Short Grx2 isoform found in the cytosolic fraction by subcellular fractionation; cytosol is the main site of Grx2 GSH-dependent oxidoreductase function. Supporting Evidence: PMID:11958675 it is shown that both isoforms are present in mitochondria, but only the short one is detected in the cytosolic fraction. |
| GO:0006749 glutathione metabolic process | IGI PMID:23242256 Multiple glutathione disulfide removal pathways mediate cyto... | ACCEPT | Summary: Morgan et al. (abstract-only cache) used roGFP2 probes and genetic combinations with glr1 to show Grx2 is an efficient backup pathway for cytosolic GSSG reduction. Grx2 itself catalyses GSSG reduction (also shown with dihydrolipoamide in vitro), so participation in glutathione metabolism is direct. Supporting Evidence: PMID:23242256 we identify Trx2 and Grx2 as efficient backup systems to glutathione reductase for cytosolic GSSG reduction. PMID:11958675 Grx2p also catalyses the reduction of GSSG by dihydrolipoamide with even higher efficiency. |
| GO:0015036 disulfide oxidoreductase activity | IMP PMID:9571241 The yeast Saccharomyces cerevisiae contains two glutaredoxin... | MODIFY | Summary: grx2 mutants retain only 20% of heat-stable HED-reducing activity, and grx1 grx2 has none. The assay is GSH-dependent mixed-disulfide reduction, so the more specific glutathione disulfide oxidoreductase activity (already the IBA term and the module term) applies. Reason: More specific GSH-dependent term available and supported by the same assay. Proposed replacements: glutathione disulfide oxidoreductase activity Supporting Evidence: PMID:9571241 the grx2 mutant displayed only 20% of the wild-type activity, indicating that Grx2 accounted for the majority of this activity in vivo. PMID:9571241 Strains deleted for both GRX1 and GRX2 were viable but lacked heat-stable oxidoreductase activity using beta-hydroxyethylene disulfide as a substrate. |
| GO:0015038 glutathione disulfide oxidoreductase activity | IBA GO_REF:0000033 | ACCEPT | Summary: Core MF. IBA from dithiol glutaredoxin node PTN000018533; Grx2 has direct evidence (major cellular HED/GSH activity; recombinant enzyme active; 15-fold higher specific activity than Grx1). Supporting Evidence: PMID:9571241 the grx2 mutant displayed only 20% of the wild-type activity, indicating that Grx2 accounted for the majority of this activity in vivo. PMID:11958675 Recombinant yeast Grx2p, expressed in Escherichia coli, behaves as a 'classical' Grx that efficiently catalyses the reduction of hydroxyethyl disulphide by GSH. PMID:18992757 yGrx2 has a specific activity 15 times higher than that of yGrx1 |
| GO:0034599 cellular response to oxidative stress | IBA GO_REF:0000033 | ACCEPT | Summary: IBA for oxidative stress response; supported by Grx2-specific IMP (H2O2 sensitivity). Supporting Evidence: PMID:9571241 a grx1 mutant was sensitive to oxidative stress induced by the superoxide anion, whereas a strain that lacked GRX2 was sensitive to hydrogen peroxide. |
| GO:0034599 cellular response to oxidative stress | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA rule; correct for Grx2. Supporting Evidence: PMID:9571241 a grx1 mutant was sensitive to oxidative stress induced by the superoxide anion, whereas a strain that lacked GRX2 was sensitive to hydrogen peroxide. |
| GO:0034599 cellular response to oxidative stress | IMP PMID:9571241 The yeast Saccharomyces cerevisiae contains two glutaredoxin... | ACCEPT | Summary: grx2 mutants are hypersensitive to H2O2; GRX2 is induced by oxidative stress. Supporting Evidence: PMID:9571241 a grx1 mutant was sensitive to oxidative stress induced by the superoxide anion, whereas a strain that lacked GRX2 was sensitive to hydrogen peroxide. |
| GO:0098869 cellular oxidant detoxification | IEA GO_REF:0000108 | KEEP AS NON CORE | Summary: Inter-ontology IEA from glutathione peroxidase activity. Grx2 reduces hydroperoxides and protects against H2O2, but this is secondary to GSH-dependent disulfide reduction. Supporting Evidence: PMID:12684511 We now show that Grx2 is also a general hydroperoxidase, and kinetic data indicate that both enzymes have a similar pattern of activity, which is highest with hydrogen peroxide, followed by cumene hydroperoxide and tert-butyl hydroperoxide. PMID:11875065 Elevating the gene dosage of GRX1 or GRX2 increases resistance to hydroperoxides including hydrogen peroxide, tert-butyl hydroperoxide and cumene hydroperoxide. |
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Download this section (compressed HTML)Q: What is the specific function of the mitochondrial Grx2 isoform, given overlap with the monothiol Grx5 and mitochondrial Trx3?
Q: Which electron donor supports Grx2-mediated GSSG reduction in the glr1 cytosol in vivo (thioredoxin reductase, lipoamide)?
Experiment: Compare matrix roGFP2-based EGSH and protein glutathionylation in M35V (mitochondria-only) versus M1 mutant (cytosol-only) GRX2 alleles under H2O2.
Hypothesis: The mitochondrial Grx2 isoform protects matrix proteins from glutathionylation under oxidative stress.
Cytoplasmic glutaredoxin; thioltransferase, glutathione-dependent disulfide oxidoreductase involved in maintaining redox state of target proteins, also exhibits glutathione peroxidase activity, expression induced in response to stress; GRX2 has two in-frame start codons resulting in a shorter isoform that is retained in the cytosol and a longer form translocated to the mitochondrial matrix; GRX2 has a paralog, GRX1, that arose from the whole genome duplication
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