Protein Variants | Comment | Organism |
---|---|---|
additional information | generation of stromal and thylakoid membrane-bound ascorbate peroxidases (sAPX and tAPX, respectively) knockout mutants, exhibiting no visible phenotype under high-light (HL) stress. The Arabidopsis thaliana sapx/tapx double mutant is crossed with a proton gradient regulation 5 (pgr5) single mutant, wherein both DELTApH-dependent mechanisms are impaired. The sapx/tapx/pgr5 triple mutant exhibits extreme sensitivity to HL compared with its parental lines. This phenotype is consistent with cellular redox perturbations and enhanced expression of many oxidative stress-responsive genes. These findings demonstrate that the PGR5-dependent mechanisms compensate for chloroplast APXs, and vice versa. The failure of induction of non-photochemical quenching in pgr5 (because of the limitation in DELTApH formation) is partially recovered in sapx/tapx/pgr5 mutants. This recovery is dependent on the NADH dehydrogenase-like complex-dependent pathway for cyclic electron flow around photosystem I | Arabidopsis thaliana |
Localization | Comment | Organism | GeneOntology No. | Textmining |
---|---|---|---|---|
chloroplast | - |
Arabidopsis thaliana | 9507 | - |
chloroplast stroma | - |
Arabidopsis thaliana | 9570 | - |
thylakoid membrane | membrane-bound | Arabidopsis thaliana | 42651 | - |
Metals/Ions | Comment | Organism | Structure |
---|---|---|---|
Fe2+ | in the heme group | Arabidopsis thaliana |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
2 L-ascorbate + H2O2 + 2 H+ | Arabidopsis thaliana | - |
L-ascorbate + L-dehydroascorbate + 2 H2O | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Arabidopsis thaliana | Q42592 | - |
- |
Arabidopsis thaliana | Q42593 | - |
- |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
2 L-ascorbate + H2O2 + 2 H+ | - |
Arabidopsis thaliana | L-ascorbate + L-dehydroascorbate + 2 H2O | - |
? |
Synonyms | Comment | Organism |
---|---|---|
APXS | gene name, UniProt | Arabidopsis thaliana |
APXT | gene name, UniProt | Arabidopsis thaliana |
AT1G77490 | gene name, UniProt | Arabidopsis thaliana |
AT4G08390 | gene name, UniProt | Arabidopsis thaliana |
sAPX | - |
Arabidopsis thaliana |
stromal ascorbate peroxidases | - |
Arabidopsis thaliana |
tAPX | - |
Arabidopsis thaliana |
thylakoid membrane-bound ascorbate peroxidases | - |
Arabidopsis thaliana |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
heme | - |
Arabidopsis thaliana |
General Information | Comment | Organism |
---|---|---|
malfunction | stromal and thylakoid membrane-bound ascorbate peroxidases (sAPX and tAPX, respectively) knockout mutants do not exhibit a visible phenotype under high-light (HL) stress. PGR5-dependent mechanisms compensate for chloroplast APXs, and vice versa | Arabidopsis thaliana |
physiological function | stromal and thylakoid membrane-bound ascorbate peroxidases (sAPX and tAPX, respectively) are major H2O2-scavenging enzymes in chloroplasts. PGR5-dependent mechanisms compensate for chloroplast APXs, and vice versa under high-light stress | Arabidopsis thaliana |