EC Number   |
General Information |
Reference |
|---|
    1.1.1.81 | evolution |
HPR1 and HPR2 are the major hydroxypyruvate-reducing enzymes in leaves |
-, 763559 |
| 1.1.1.81 | evolution |
no hydroxyphenylpyruvate reductase (HPPR) activity by isozyme HPPR4 from Arabidopsis thaliana. Isozyme HPPR2 mainly shows hydroxypyruvate reductase (HPR) activity, while isozyme HPPR3 mainly shows 4-hydroxyphenylpyruvate reductase (EC 1.1.1.237) activity. Enzyme HPPR2 belongs to the family of D-isomer-specific 2-hydroxyacid dehydrogenases, group II |
761180 |
| 1.1.1.81 | evolution |
the enzyme belongs to the beta-HAD (beta-hydroxyacid dehydrogenase) protein family. AtHPR2 and AtHPR3 are 45% identical to each other at the amino acid level, but only 19-25% identical to AtHPR1, the NADH-dependent form, and 8-9% identical to the AtGLYRs. None of the AtHPRs contains the active-site residues conserved in AtGLYR1 and AtGLYR2, indicating that the sites responsible for reducing glyoxylate differ greatly between the AtGLYRs and AtHPRs |
737745 |
| 1.1.1.81 | malfunction |
Arabidopsis thaliana mutants defective in either HPPR2 or HPPR3 isozyme contain lower amounts of pHPL and are impaired in conversion of tyrosine to pHPL. Furthermore, a loss-of-function mutation in tyrosine aminotransferase (TAT) also reduces the pHPL accumulation in plants |
-, 761180 |
| 1.1.1.81 | 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 |
-, 763559 |
| 1.1.1.81 | malfunction |
deletion of HPR3 results in slightly altered leaf concentrations of the photorespiratory intermediates HP, glycerate, and glycine, indicating a disrupted photorespiratory flux, but not in visible alteration of the phenotype. The combined deletion of HPR1, HPR2, and HPR3 causes increased growth retardation, decreased photochemical efficiency, and reduced oxygen-dependent gas exchange in comparison with the hpr1xhpr2 double mutant. HPR mutants show impaired growth and contain less chlorophyll, phenotypes, detailed overview |
-, 763584 |
| 1.1.1.81 | malfunction |
deletion of photorespiratory enzymes typically leads to a strong air sensitivity of the respective mutants, which can be fully recovered by elevated-CO2 conditions. While this is a distinctive feature of most photorespiratory mutants, Arabidopsis thaliana HPR1 knockout mutants grow nearly normally in ambient air with moderate photoperiods and show only minor changes in photosynthetic and metabolic parameters under these conditions. The additional deletion of the cytosolic HPR2 distinctly elevates the oxygen sensitivity, but this hpr1xhpr2 double mutant can still survive long-term exposure to ambient air |
-, 763584 |
| 1.1.1.81 | metabolism |
in vitro characterization of the recombinant proteins reveals that HPPR2 has both hydroxypyruvate reductase (HPR EC 1.1.1.81, main activity) and hydroxyphenylpyruvate reductase (HPPR, EC 1.1.1.237) activities, whereas HPPR3 has a strong preference for pHPP, and both enzymes are localized in the cytosol. In Arabidopsis thaliana, HPPR2 and HPPR3, together with tyrosine aminotransferase 1 (TAT1), constitute to a probably conserved biosynthetic pathway from tyrosine to 4-hydroxyphenyllactic acid (pHPL), from which some specialized metabolites, such as rosmarinic acid (RA), can be generated in specific groups of plants. Role of HPPR in the tyrosine conversion pathway, overview |
-, 761180 |
| 1.1.1.81 | metabolism |
NADH-HPR is extensively involved in carbon metabolism |
695413 |
| 1.1.1.81 | physiological function |
Arabidopsis mutants defective in either isoform HPPR2 or HPPR3 contain lower amounts of 4-hydroxyphenyllactic acid and are impaired in conversion of tyrosine to 4-hydroxyphenyllactic acid |
-, 761180 |
