Intermediates of tocopherol biosynthesis in the unicellular alga <i>Scenedesmus obliquus</i>. The presence of three isomeric methylphytylbenzoquinones

Henry, Alison; Powls, Roy; Pennock, J. F.

doi:10.1042/bj2420367

Cited by 14 publications

(5 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The results of these experiments clearly showed that the SLL0418 protein was capable of methylating reduced or oxidated MPBQ with similar efficiency (specific activity=395±40 pmol/mg protein/h and 404±20 pmol/mg protein/h for reduced and oxidized MPBQ, respectively). The radiolabeled reduced and oxidized products migrated to the reported R f for 2,3‐dimethyl‐6‐phytylbenzoquinol and quinone [8], respectively (data not shown).…”

Section: Resultsmentioning

confidence: 85%

See 1 more Smart Citation

The role of 2‐methyl‐6‐phytylbenzoquinone methyltransferase in determining tocopherol composition in Synechocystis sp. PCC6803

2001

View full text Add to dashboard Cite

A putative 2-methyl-6-phytylbenzoquinone (MPBQ) methyltransferase gene, SLL0418, was identified from the Synechocystis PCC6803 genome based on its homology to previously characterized Q Q-tocopherol methyltransferases. Genetic and biochemical evidence confirmed open reading frame (ORF) SLL0418 encodes a MPBQ methyltransferase. An SLL0418 partial knockout mutant accumulated L L-tocopherol with no effect in the overall tocopherol content of the cell. In vitro assays of the SLL0418 gene expressed in Escherichia coli showed the enzyme efficiently catalyzes methylation of ring carbon 3 of MPBQ. In addition, the enzyme also catalyzes the methylation of ring carbon 3 of 2-methyl-6-solanylbenzoquinol in the terminal step of plastoquinone biosynthesis. ß

show abstract

Section: Resultsmentioning

confidence: 85%

“…A mixture of six different isomers of methylphytylbenzoquinone was synthesized as described by Henry et al [8]. 250 μg of the mixed isomer preparation was suspended in ethylether and oxidized by adding 100 mg of silver oxide and incubating for 2 h at room temperature.…”

Section: Methodsmentioning

confidence: 99%

The role of 2‐methyl‐6‐phytylbenzoquinone methyltransferase in determining tocopherol composition in Synechocystis sp. PCC6803

2001

View full text Add to dashboard Cite

show abstract

“…The substrate MPBQ and a standard for the reaction product 2,3-dimethyl-5-phytylbenzoquinol for the methyltransferase assay were prepared as described previously Henry et al, 1987). Cell pellets expressing Anab-VTE3, At-VTE3, or vte3-1 protein were thawed on ice and resuspended in 4 mL of extraction buffer XB [10 mM Hepes-KOH, pH 7.8, 5 mM DTT, 1 mM 4-(2-aminoethyl) benzenesulfonyl fluoride, 0.1 mM aprotinin, and 1 mg/mL leupeptin].…”

Section: -Methyl-6-phytylbenzoquinol (Mpbq) Methyltransferase Enzymementioning

confidence: 99%

Engineering Vitamin E Content: From Arabidopsis Mutant to Soy Oil

Eenennaam

Lincoln²,

Durrett³

et al. 2003

Plant Cell

234

176

View full text Add to dashboard Cite

We report the identification and biotechnological utility of a plant gene encoding the tocopherol (vitamin E) biosynthetic enzyme 2-methyl-6-phytylbenzoquinol methyltransferase. This gene was identified by map-based cloning of the Arabidopsis mutation vitamin E pathway gene3-1 ( vte3-1 ), which causes increased accumulation of ␦ -tocopherol and decreased ␥ -tocopherol in the seed. Enzyme assays of recombinant protein supported the hypothesis that At-VTE3 encodes a 2-methyl-6-phytylbenzoquinol methyltransferase. Seed-specific expression of At-VTE3 in transgenic soybean reduced seed ␦ -tocopherol from 20 to 2%. These results confirm that At-VTE3 protein catalyzes the methylation of 2-methyl-6-phytylbenzoquinol in planta and show the utility of this gene in altering soybean tocopherol composition. When At-VTE3 was coexpressed with At-VTE4 ( ␥ -tocopherol methyltransferase) in soybean, the seed accumulated to Ͼ 95% ␣ -tocopherol, a dramatic change from the normal 10%, resulting in a greater than eightfold increase of ␣ -tocopherol and an up to fivefold increase in seed vitamin E activity. These findings demonstrate the utility of a gene identified in Arabidopsis to alter the tocopherol composition of commercial seed oils, a result with both nutritional and food quality implications.

show abstract

“…Chemical synthesis and purification of 2-methyl-6-phytylbenzoquinone substrate were as reported by Peddibhotla et al (2002). 2-Methyl-6-solanylbenzoquinone substrate was extracted and purified from iris bulbs as described by Henry et al (1987).…”

Section: Escherichia Colimentioning

confidence: 99%

Highly Divergent Methyltransferases Catalyze a Conserved Reaction in Tocopherol and Plastoquinone Synthesis in Cyanobacteria and Photosynthetic Eukaryotes

Cheng

Sattler

Maéda

et al. 2003

THE PLANT CELL ONLINE

193

176

View full text Add to dashboard Cite

Tocopherols are lipid-soluble compounds synthesized only by photosynthetic eukaryotes and oxygenic cyanobacteria. The pathway and enzymes for tocopherol synthesis are homologous in cyanobacteria and plants except for 2-methyl-6-phytyl-1,4-benzoquinone/2-methyl-6-solanyl-1,4-benzoquinone methyltransferase (MPBQ/MSBQ MT), which catalyzes a key methylation step in both tocopherol and plastoquinone (PQ) synthesis. Using a combined genomic, genetic, and biochemical approach, we isolated and characterized the VTE3 (vitamin E defective) locus, which encodes MPBQ/MSBQ MT in Arabidopsis. The phenotypes of vte3 mutants are consistent with the disruption of MPBQ/MSBQ MT activity to varying extents. The ethyl methanesulfonate-derived vte3-1 allele alters tocopherol composition but has little impact on PQ levels, whereas the null vte3-2 allele is deficient in PQ and ␣ -and ␥ -tocopherols. In vitro enzyme assays confirmed that VTE3 is the plant functional equivalent of the previously characterized MPBQ/MSBQ MT (Sll0418) from Synechocystis sp PCC6803, although the two proteins are highly divergent in primary sequence. Sll0418 orthologs are present in all fully sequenced cyanobacterial genomes, Chlamydomonas reinhardtii , and the diatom Thalassiosira pseudonana but absent from vascular and nonvascular plant databases. VTE3 orthologs are present in all vascular and nonvascular plant databases and in C. reinhardtii but absent from cyanobacterial genomes. Intriguingly, the only prokaryotic genomes that contain VTE3-like sequences are those of two species of archea, suggesting that, in contrast to all other enzymes of the plant tocopherol pathway, the evolutionary origin of VTE3 may have been archeal rather than cyanobacterial. In vivo analyses of vte3 mutants and the corresponding homozygous Synechocystis sp PCC6803 sll0418 :: aphII mutant revealed important differences in enzyme redundancy, the regulation of tocopherol synthesis, and the integration of tocopherol and PQ biosynthesis in cyanobacteria and plants.

show abstract

Intermediates of tocopherol biosynthesis in the unicellular alga Scenedesmus obliquus. The presence of three isomeric methylphytylbenzoquinones

Cited by 14 publications

References 24 publications

The role of 2‐methyl‐6‐phytylbenzoquinone methyltransferase in determining tocopherol composition in Synechocystis sp. PCC6803

The role of 2‐methyl‐6‐phytylbenzoquinone methyltransferase in determining tocopherol composition in Synechocystis sp. PCC6803

Engineering Vitamin E Content: From Arabidopsis Mutant to Soy Oil

Highly Divergent Methyltransferases Catalyze a Conserved Reaction in Tocopherol and Plastoquinone Synthesis in Cyanobacteria and Photosynthetic Eukaryotes

Contact Info

Product

Resources

About