Cloned (Comment) | Organism |
---|---|
gene VTC2, quantitative RT-PCR enzyme expression analysis | Chlamydomonas reinhardtii |
Protein Variants | Comment | Organism |
---|---|---|
additional information | Chlamydomonas reinhardtii strain cw15-325 is used as recipient strain for transformation with VTC2 amiRNA. The VTC2 gene encoding GDP-L-galactose phosphorylase is targeted using artificial microRNAs. Upon H2O2 stress, alanine and proline accumulated, whereas the amount of cystine strongly decreases in the VTC2 amiRNA lines. The amounts of aspartic acid, lysine and ornithine are lower in the VTC2 amiRNA lines under control conditions, but these differences are much smaller following H2O2 stress. Changes in the tricarboxylic acid cycle intermediates are also apparent. Following H2O2 treatment, the amount of pyruvic acid and citric acid decreases, but the amounts of malic acid and succinic acid increases in all the lines. Furthermore, the amount of mannose and glycerol-3-phosphate decreases in the VTC2 amiRNA lines. Phenotype analysis, overview | Chlamydomonas reinhardtii |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
GDP-alpha-D-glucose + alpha-D-mannose 1-phosphate | Chlamydomonas reinhardtii | - |
alpha-D-glucose 1-phosphate + GDP-alpha-D-mannose | - |
? | |
GDP-alpha-D-glucose + alpha-D-mannose 1-phosphate | Chlamydomonas reinhardtii cw15-325 | - |
alpha-D-glucose 1-phosphate + GDP-alpha-D-mannose | - |
? | |
GDP-beta-L-galactose + alpha-D-mannose 1-phosphate | Chlamydomonas reinhardtii | - |
beta-L-galactose 1-phosphate + GDP-alpha-D-mannose | - |
? | |
GDP-beta-L-galactose + alpha-D-mannose 1-phosphate | Chlamydomonas reinhardtii cw15-325 | - |
beta-L-galactose 1-phosphate + GDP-alpha-D-mannose | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Chlamydomonas reinhardtii | A0A2K3D0V9 | - |
- |
Chlamydomonas reinhardtii cw15-325 | A0A2K3D0V9 | - |
- |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
GDP-alpha-D-glucose + alpha-D-mannose 1-phosphate | - |
Chlamydomonas reinhardtii | alpha-D-glucose 1-phosphate + GDP-alpha-D-mannose | - |
? | |
GDP-alpha-D-glucose + alpha-D-mannose 1-phosphate | - |
Chlamydomonas reinhardtii cw15-325 | alpha-D-glucose 1-phosphate + GDP-alpha-D-mannose | - |
? | |
GDP-beta-L-galactose + alpha-D-mannose 1-phosphate | - |
Chlamydomonas reinhardtii | beta-L-galactose 1-phosphate + GDP-alpha-D-mannose | - |
? | |
GDP-beta-L-galactose + alpha-D-mannose 1-phosphate | - |
Chlamydomonas reinhardtii cw15-325 | beta-L-galactose 1-phosphate + GDP-alpha-D-mannose | - |
? |
Synonyms | Comment | Organism |
---|---|---|
GDP-galactose:glucose-1-phosphate guanyltransferase | UniProt | Chlamydomonas reinhardtii |
Vtc2 | - |
Chlamydomonas reinhardtii |
Organism | Comment | Expression |
---|---|---|
Chlamydomonas reinhardtii | expression of the VTC2 gene is rapidly induced by H2O2 and 1O2 resulting in a manifold increase in ascorbate content. The Chlamydomonas reinhardtii cell wall-deficient strain cw15-325 carrying a mutation in the argininosuccinate lyase (ARG7) with the VTC2-specific amiRNA vectors. In the case of the CDS-targeting amiRNA (VTC2-A) construct, 96 arginine-prototrophic colonies are tested by PCR and 89 of them are found to carry the whole amiRNA cassette. For the VTC2 3'-UTR-targeting amiRNA (VTC2-B) construct, 45 of the 96 tested arginine-prototrophic colonies carry the whole amiRNA cassette. Their Asc content shows a strong reduction (at least 80% reduction in 70% of the strains). In the VTC2 amiRNA lines, the mRNA abundances of APX1 and DHAR1, the main chloroplastic forms, are about 40% lower than in the EV2 control. The mutant lines also respond to high-light treatment | up |
General Information | Comment | Organism |
---|---|---|
malfunction | the VTC2 amiRNA lines grow more slowly, have lower chlorophyll content, and are more susceptible to stress than the control strains. Ascorbate concentrations in VTC2 amiRNA lines are reduced to 10% of wild-type level. In the VTC2 amiRNA lines, the mRNA abundances of APX1 and DHAR1, the main chloroplastic forms, are about 40% lower than in the EV2 control | Chlamydomonas reinhardtii |
metabolism | Chlamydomonas VTC2 lacks negative feedback regulation by ascorbate in the physiological concentration range. Ascorbate biosynthesis is also highly regulated in Chlamydomonas albeit via mechanisms distinct from those described in land plants. Dependence of Asc biosynthesis on the photosynthetic electron transport chain | Chlamydomonas reinhardtii |
physiological function | GDP-L-galactose phosphorylase plays a pivotal role in ascorbate biosynthesis. In contrast to plants, there is no circadian regulation of ascorbate biosynthesis, photosynthesis is not required per se for ascorbate biosynthesis, and Chlamydomonas VTC2 lacks negative feedback regulation by ascorbate in the physiological concentration range | Chlamydomonas reinhardtii |