Cloned (Comment) | Organism |
---|---|
production of a triple mutant lacking all three DHARs, dhar1, dhar2, and dhar3, are crossed with each other, resulting in the generation of double mutants dhar1/dhar2, dhar1/dhar3, and dhar2/dhar3. Among these double mutants, dhar1/dhar3 and dhar2/dhar3 are further crossed with each other to generate the triple-knockout mutant dhar1/dhar2/dhar3 (termed DELTAdhar), which is isolated from the F2 population by using PCR-based genotyping | Arabidopsis thaliana |
Protein Variants | Comment | Organism |
---|---|---|
additional information | generation of DELTAdhar Arabidopsis plants as well as a quadruple mutant line combining DELTAdhar with an additional vtc2 mutation that causes ascorbate deficiency. Measurements of ascorbate in these mutants under low- or high-light conditions indicate that DHARs have a nonnegligible impact on full ascorbate accumulation under high light, but that they are dispensable when ascorbate concentrations are low to moderate. Because GSH itself can reduce DHA nonenzymatically, the pad2 mutant is used that contains about 30% of the wild-type GSH level. The pad2 mutant accumulates ascorbate at a wild-type level under high light, but when the pad2 mutation is combined with DELTAdhar, there is near-complete inhibition of high-light-dependent ascorbate accumulation. The lack of ascorbate accumulation is consistent with a marked increase in the ascorbate degradation product threonate. These findings indicate that ascorbate recycling capacity is limited in DELTAdhar pad2 plants, and that both DHAR activity and GSH content set a threshold for high-light-induced ascorbate accumulation. Each gene knockout is confirmed by reverse transcription PCR. The measurement of DHAR activity reveals that DHAR1 and DHAR3 are the major isoforms, and that the triple DELTAdhar mutant has negligible DHAR activity. DHAR loss-of-function does not affect MDAR activity | Arabidopsis thaliana |
Localization | Comment | Organism | GeneOntology No. | Textmining |
---|---|---|---|---|
chloroplast | - |
Arabidopsis thaliana | 9507 | - |
cytosol | - |
Arabidopsis thaliana | 5829 | - |
peroxisome | - |
Arabidopsis thaliana | 5777 | - |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
2 glutathione + dehydroascorbate | Arabidopsis thaliana | - |
glutathione disulfide + ascorbate | - |
? | |
2 glutathione + dehydroascorbate | Arabidopsis thaliana Col-0 | - |
glutathione disulfide + ascorbate | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Arabidopsis thaliana | Q8LE52 | - |
- |
Arabidopsis thaliana | Q9FRL8 | - |
- |
Arabidopsis thaliana | Q9FWR4 | - |
- |
Arabidopsis thaliana Col-0 | Q8LE52 | - |
- |
Arabidopsis thaliana Col-0 | Q9FRL8 | - |
- |
Arabidopsis thaliana Col-0 | Q9FWR4 | - |
- |
Source Tissue | Comment | Organism | Textmining |
---|---|---|---|
leaf | - |
Arabidopsis thaliana | - |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
2 glutathione + dehydroascorbate | - |
Arabidopsis thaliana | glutathione disulfide + ascorbate | - |
? | |
2 glutathione + dehydroascorbate | - |
Arabidopsis thaliana Col-0 | glutathione disulfide + ascorbate | - |
? |
Synonyms | Comment | Organism |
---|---|---|
At1g19570 | locus name | Arabidopsis thaliana |
At1g75270 | locus name | Arabidopsis thaliana |
At5g16710 | locus name | Arabidopsis thaliana |
AtDHAR1 | - |
Arabidopsis thaliana |
AtDHAR2 | - |
Arabidopsis thaliana |
AtDHAR3 | - |
Arabidopsis thaliana |
dehydroascorbate reductase | - |
Arabidopsis thaliana |
DHA reductase | - |
Arabidopsis thaliana |
DHAR | - |
Arabidopsis thaliana |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
22 | - |
assay at room temperature | Arabidopsis thaliana |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
7 | - |
assay at | Arabidopsis thaliana |
General Information | Comment | Organism |
---|---|---|
physiological function | the DHA reductases (DHARs) that catalyze the GSH-dependent DHA reduction allows plants to rapidly recycle ascorbate from DHA. Cooperation of DHARs and GSH is required for ascorbate accumulation under high-light stress in Arabidopsis thaliana | Arabidopsis thaliana |