Deacetylvindoline 4-O-acetyltransferase

Salutaridinol 7-0-acetyltransferase catalyzes the conversion of the phenanthrene alkaloid salutaridinol to salutaridinol-7-Oacetate, the immediate precursor of thebaine along the morphine biosynthetic pathway in P. somniferum (Fig. 10.7).26 Acetyl CoA-dependent acetyltransferases have an important role in plant alkaloid metabolism. They are involved in the synthesis of monoterpenoid indole alkaloids in medicinal plant species such as Rauwolfia serpentina. In this plant, the enzyme vinorine synthase transfers an acetyl group from acetyl CoA to 16-epi-vellosimine to form vinorine. This acetyl transfer is accompanied by a concomitant skeletal rearrangement from the sarpagan- to the ajmalan-type (reviewed in2). An acetyl CoA-dependent acetyltransferase also participates in vindoline biosynthesis in Catharanthus roseus, the source of the chemotherapeutic dimeric indole alkaloid vinblastine (reviewed in2). Acetyl CoA deacetylvindoline 4-O-acetyltransferase catalyzes the last step in vindoline biosynthesis. A cDNA encoding acetyl CoA deacetylvindoline 4-0-acetyltransferase was recently successfully isolated.27... 

The translation of the sequence of the cDNA encoding deacetylvindoline 4-O-acetyltransferase compared to other putative plant acetyltransferases revealed a conserved region near the carboxy terminus of the proteins. This sequence was used to design a degenerate antisense oligodeoxynucleotide primer for PCR. The sense primer was based upon an internal peptide sequence of salutaridinol 7-0-acetyltransferase. This approach finally yielded a partial cDNA that encoded salutaridinol 7-O-acetyltransferase. The full-length clone was obtained by RACE-PCR and was functionally expressed in S. frugiperda Sf9 cells.28 The amino acid sequence of salutaridinol 7-O-acetyltransferase is most similar (37% identity) to that of deacetylvindoline acetyltransferase of C. roseus.27... 

Fig. (6). Biosynthesis of vindoline from tabersonine. T16H tabcrsonine 16-hydroxylase OMT i -adenosyl -/.-methionine 16-hydroxytabersonine - 16-O-methyltransferase NMT S-adenosyl - /.-methionine 16-methoxy - 2,3-dihydro-3-hydroxytabersonine - iV-methyltransferase D4H desacetoxy vindoline 4-hydroxylase DAT acetyl coenzyme A 4-O-deacetylvindoline 4-O-acetyltransferase.

Fig. 8.7 Biosynthetic pathway for monoteipenoid indole alkaloid (MIA) biosynthesis in plants. TDC tryptophan decarboxylase, STR strictosidine synthase, SGD strictosidine -o-glucosidase, T16H tabersonine 16-hydroxylase, D4H desacetoxyvindolme 4-hydroxylase, DAT deacetylvindoline 4-O-acetyltransferase (Adopted from Ref. [3])...

Four genes and six steps are involved in the synthesis of vindoUne in the leaves of C. roseus. Tabersonine 16-hydroxylase (T16H) anchored to the ER catalyzes the first step of vindoUne biosynthesis. 16-Hydroxytabersonine 16-0-methyltransferase (160MT) homodimers (excluded from nucleus) in the cytoplasm of aerial organ epidermis catalyzes the second step. Desacetoxyvindoline-4-hydroxylase (D4H) and deacetylvindoline-4-O-acetyltransferase (DAT), located in the nucleocytoplasmic compartment,... 

Magnotta, M., Murata, J., Chen, and de Luca, V. (2007) Expression of deacetylvindoline-4-O-acetyltransferase in Catharanthus roseus hairy roots. Phytochemistry, 68, 1922-1931. 

Figure 4.9 Biosynthesis of monoterpenoid indole alkaloids. Enzyme abbreviations TDC, tryptophan decarboxylase STR, strictosidine synthase SGD, strictosidine f-d-glucosidase T16H, tabersonine 16-hydroxylase D4H, desacetoxyvindoline 4-hydroxylase DAT, deacetylvindoline 4-O-acetyltransferase.

Figure 2.11 Biosynthesis of vindoline, catharanthine and the dimeric alkaloids vinblastine and vincristine. T16H, tabersonine-16-hydroxylase OMT, 5-adenosylmethionine 16-hydroxy-tabersonine-O-methyltransferase NMT, 5-adenosylmethionine 16-methoxy-2,3-dihydro-3-hydroxymethyltabersonine-/ /-methyltransferase D4H, desacetoxy-vindoline-4-dioxygenase DAT, acetylcoenzyme A 4-0-deacetylvindoline-4-0-acetyltransferase.

Fig. 8.5 Compartmentation of alkaloid biosynthesis in Cathamnthus roseus. AS anthianilate synthase, CR NADPH cathenamine reductase, DAT deacetylvindoline 17-O-acetyltransferase, ER endoplasmic reticulum, GlOH geraniol 10-hydroxylase, GAP glyceraldehyde-3-phosphate, NMT S-adenosyl-L-methionine methoxy-2, 16-dihydro-16-hydioxylagersonine-lV-methyltransferase, OHT desacetoxyvindoline-4-hydroxylase, SGD strictosidine -glucosidase, STR strictosidine synthase TDC tryptophan decarboxylase, THAS NADPH tetrahydroalstonine reductase (Adopted from Ref. [10])... 

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