EC Number   |
General Information |
Reference |
|---|
    2.5.1.115 | malfunction |
disruption of Synechocystis sp. PCC 6803 HPT function causes an absence of tocopherols without affecting plastoquinone-9 levels, indicating that separate polyprenyltransferases exist for tocopherol and plastoquinone synthesis in Synechocystis sp. PCC 6803 |
726214 |
| 2.5.1.115 | physiological function |
a null mutant obtained by insertional inactivation does not accumulate tocopherols, and is rescued by the Arabidopsis HPT1 ortholog. The membrane fraction of wild-type Synechocystis sp. PCC 6803 is capable of catalyzing the phytylation of homogentisate, whereas the membrane fraction from the slr1736 null mutant is not |
728504 |
| 2.5.1.115 | physiological function |
a Synechocystis sp. PCC 6803 homogentisate phytyltransferase null mutant is rescued by the Arabidopsis HPT1 ortholog. Antisense expression of HPT1 in Arabidopsis results in reduced seed tocopherol levels, whereas seed-specific sense expression results in increased seed tocopherol levels |
728504 |
| 2.5.1.115 | physiological function |
abiotic stress results in an 18 and 8fold increase in total tocopherol content in wild-type and isoform HPT1 overexpressing leaves, respectively, with tocopherol levels in the ovrexpressing strain being 2- to 4fold higher than wild type at all experimental time points. Increased total tocopherol levels correlate with elevated HPT mRNA levels and HPT specific activity, suggesting that HPT activity limits total tocopherol synthesis during abiotic stress. Overexpression of gamma-tocopherol methyltransferase in the HPT1 overexpression strain results in nearly complete conversion of gamma- and delta-tocopherols to alpha- and beta-tocopherols |
728507 |
| 2.5.1.115 | physiological function |
an Arabidopsis thalina that accumulates tocotrienols and homogentisate by co-expression of Arabidopsis thaliana hydroxyphenylpyruvate dioxygenase and Escherichia coli bi-functional chorismate mutase/prephenate dehydrogenase loses tocotrienol production when crossed into the vte2-1 HPT null mutant. Hydroxyphenylpyruvate dioxygenase/TyrA-induced tocotrienol production requires HPT and occurs upon enrichment of geranylgeranyl diphosphaterelative to phytyl diphosphate in prenyl diphosphate pools |
728486 |
| 2.5.1.115 | physiological function |
expression of homogentisate phytyltransferase, tocopherol cyclase, and gamma-tocopherol methyltransferase on a synthetic operon to synthesize vitamin E in leaves of Nicotiana tabacum and Lycopersicum esculentum. Homogentisate phytyltransferase is the limiting enzymatic step in the pathway. An up to tenfold increase in total tocochromanol accumulation is achieved. A light-dependent regulatory link exosts between tocochromanol metabolism and the pathways of photosynthetic pigment biosynthesis |
739537 |
| 2.5.1.115 | physiological function |
in leaves, isoform HPT1 constitutive overexpression results in a 10fold increase in HPT specific activity and a 4.4fold increase in total tocopherol content relative to wild type. In seeds, HPT1 overexpression results in a 4fold increase in HPT specific activity and a total seed tocopherol content that is 40% higher than wild type, primarily because of an increase in gamma-tocopherol content. This enlarged pool of gamma-tocopherol is almost entirely converted to alpha-tocopherol by crossing HPT1 overexpressing plants with lines constitutively overexpressing gamma-tocopherol methyltransferase. Seed of the resulting double-overexpressing lines displays a 12fold increase in vitamin E activity relative to wild type |
728505 |
| 2.5.1.115 | physiological function |
seed-specific expression of isoform VTE2-2 in Arabidopsis results in increased seed-tocopherol levels |
728534 |
| 2.5.1.115 | physiological function |
SLR1736 gene disruption does not lead to significant differences in cellular plastoquinone, phylloquinone, and chlorophyll levels, but causes absence of tocopherols without affecting plastoquinone-9 levels |
726214 |
| 2.5.1.115 | physiological function |
T1 leaves of transgenic tomato plants overexpressing the apple enzyme contain1.8- to 3.6fold and1.6- to 2.9fold higher levels of alpha-tocopherol and gamma-tocopherol, respectively, than those in control plants. The levels of alpha-tocopherol and gamma-tocopherol in T1 fruits increases up to 1.7fold and 3.1fold, respectively |
728443 |
