Cloned (Comment) | Organism |
---|---|
gene HPR2, At1g70870, recombinant expression of tagged HPR2 in a hpr1-knockout mutant Arabidopsis thaliana strain, RT-PCR enzyme expression analysis | Arabidopsis thaliana |
Protein Variants | Comment | Organism |
---|---|---|
additional information | deletion of HPR2 by T-DNA insertion, HPR2 knockout plants do not show visually noticeable impairments in air, but combined deletion of HPR1 and HPR2 is detrimental to air-grown mutants. Crossing of hpr1-1 and hpr2-1 leads to functional inactivation of both genes. Knockout of both HPR1 and HPR2 alters steady-state metabolite profiles and photorespiratory 13C fluxes. The leaf glycerate content remains essentially unaltered in the hpr2 mutant and is increased in hpr1 and the double knockout plant. Knockout of either HPR1 or HPR2 alters photosynthetic gas exchange | Arabidopsis thaliana |
Inhibitors | Comment | Organism | Structure |
---|---|---|---|
oxalate | strong inhibition | Arabidopsis thaliana |
Localization | Comment | Organism | GeneOntology No. | Textmining |
---|---|---|---|---|
cytosol | - |
Arabidopsis thaliana | 5829 | - |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
hydroxypyruvate + NADPH + H+ | Arabidopsis thaliana | - |
D-glycerate + NADP+ | - |
r | |
hydroxypyruvate + NADPH + H+ | Arabidopsis thaliana Col-0 | - |
D-glycerate + NADP+ | - |
r |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Arabidopsis thaliana | Q9CA90 | - |
- |
Arabidopsis thaliana Col-0 | Q9CA90 | - |
- |
Purification (Comment) | Organism |
---|---|
recombinant tagged enzyme HPR2 from hpr1-knockout mutant Arabidopsis thaliana strain by ammonium sulfate fractionation, ion-exchange and affinity chromatography | Arabidopsis thaliana |
Source Tissue | Comment | Organism | Textmining |
---|---|---|---|
cauline leaf | high expression level | Arabidopsis thaliana | - |
flower | lower expression level | Arabidopsis thaliana | - |
additional information | RT-PCR enzyme expression analysis, overview | Arabidopsis thaliana | - |
root | lower expression level | Arabidopsis thaliana | - |
rosette leaf | high expression level | Arabidopsis thaliana | - |
silique | moderate expression level | Arabidopsis thaliana | - |
stem | moderate expression level | Arabidopsis thaliana | - |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
hydroxypyruvate + NADH + H+ | low activity | Arabidopsis thaliana | D-glycerate + NAD+ | - |
? | |
hydroxypyruvate + NADH + H+ | low activity | Arabidopsis thaliana Col-0 | D-glycerate + NAD+ | - |
? | |
hydroxypyruvate + NADPH + H+ | - |
Arabidopsis thaliana | D-glycerate + NADP+ | - |
? | |
hydroxypyruvate + NADPH + H+ | - |
Arabidopsis thaliana | D-glycerate + NADP+ | - |
r | |
hydroxypyruvate + NADPH + H+ | - |
Arabidopsis thaliana Col-0 | D-glycerate + NADP+ | - |
? | |
hydroxypyruvate + NADPH + H+ | - |
Arabidopsis thaliana Col-0 | D-glycerate + NADP+ | - |
r | |
additional information | enzyme HPR2 shows relaxed substrate and cofactor specificity, it also has glyoxylate reductase (NADP+) activity (EC 1.1.1.79). Irreversibility of the HPR2 reaction has been reported | Arabidopsis thaliana | ? | - |
- |
|
additional information | enzyme HPR2 shows relaxed substrate and cofactor specificity, it also has glyoxylate reductase (NADP+) activity (EC 1.1.1.79). Irreversibility of the HPR2 reaction has been reported | Arabidopsis thaliana Col-0 | ? | - |
- |
Subunits | Comment | Organism |
---|---|---|
? | x * 34200, about, sequence calculation | Arabidopsis thaliana |
More | the enzyme contains a D-isomer-specific 2-hydroxyacid dehydrogenase domain | Arabidopsis thaliana |
Synonyms | Comment | Organism |
---|---|---|
cytosolic hydroxypyruvate reductase | - |
Arabidopsis thaliana |
glyoxylate/hydroxypyruvate reductase A | UniProt | Arabidopsis thaliana |
HPR2 | - |
Arabidopsis thaliana |
hydroxypyruvate reductase | - |
Arabidopsis thaliana |
NAD(P)H-dependent hydroxypyruvate reductase | - |
Arabidopsis thaliana |
NADPH-dependent hydroxypyruvate reductase | - |
Arabidopsis thaliana |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
NAD+ | - |
Arabidopsis thaliana | |
NADH | - |
Arabidopsis thaliana | |
NADP+ | - |
Arabidopsis thaliana | |
NADPH | preferred cofactor, 4fold higher activity compared to NADH | Arabidopsis thaliana |
General Information | Comment | Organism |
---|---|---|
evolution | HPR1 and HPR2 are the major hydroxypyruvate-reducing enzymes in leaves | Arabidopsis thaliana |
malfunction | deletion of HPR2 results in elevated levels of hydroxypyruvate and other metabolites in leaves. Photosynthetic gas exchange is slightly altered, especially under long-day conditions. Otherwise, the mutant closely resembles wild-type plants. The combined deletion of both HPR1 and HPR2 results in distinct air-sensitivity and a dramatic reduction in photosynthetic performance. Knockout of both HPR1 and HPR2 alters steady-state metabolite profiles. Knockout of either HPR1 or HPR2 alters photosynthetic gas exchange | Arabidopsis thaliana |
physiological function | the enzyme activity shows that photorespiratory metabolism is not confined to chloroplasts, peroxisomes, and mitochondria but also extends to the cytosol. The extent to which cytosolic reactions contribute to the operation of the photorespiratory cycle in varying natural environments might be dynamically regulated by the availability of NADH in the context of peroxisomal redox homeostasis. But isozyme HPR1 plays the dominant role in photorespiration | Arabidopsis thaliana |