Tryptophan dimethylallyltransferase

Wang J. dmaW encoding tryptophan dimethylallyltransferase in ergot alkaloid biosynthesis from Clavicipitaceous fungi. PhD dissertation, University of Kentucky, Lexington, KY, 2000. 

The early steps in the ergot alkaloid biosynthetic pathway are outlined in Fig. 1. The first determinant and rate-limiting step is the prenylation of tryptophan to 4-(y,y-dimethylallyl)tryptophan (DMAT), catalyzed by dimethy-lallyl-diphosphate L-tryptophan dimethylallyltransferase (DMAT synthase EC 2.5.1.34) (Heinstein et al., 1971 Gebler and Poulter, 1992). The prenyl group for the DMAT synthase reaction is provided in the form of dimethylallyl diphosphate (DMAPP), which is derived from mevalonic acid. After the formation of DMAT, the free amino group of this intermediate is N-methylated with a methyl group donated by S-adenosylmethionine (AdoMet). The N-methylated DMAT is then converted into chanoclavine I by closure of the... 

Heinstein PF, Lee S-L, Floss HG. Isolation of dimethylallylpyrophosphate tryptophan dimethylallyltransferase from the ergot fungus (Claviceps spec.). Biochem Biophys Res Commun 44 1244-1251, 1971. 

Incorporation of label from [2- " C]mevalonate into the ergoline ring system supported the hypothesis that the pathway involved aromatic prenylation 68). This was further supported by the identification and purification of tryptophan dimethylallyltransferase 69,70), which transferred the dimethylallyl moiety from dimethylallyl-diphosphate (DMAPP) to the 4-position on the six-membered ring of L-tryptophan. Molecular genetic studies confirmed the role of this enzyme in EA biosynthesis 39,54). 

J. Wang, IF Encoding Tryptophan Dimethylallyltransferase in Ergot Alkaloid Biosynthesis from Clavicipitaceous Fungi. Ph.D. thesis. University of Kentucky, Lexington, 2000. 

Dimethylallyl pyrophosphate L-tryptophan dimethylallyltransferase, chanoclavine-I-cyclase (D 21.2) Agroclavine, elymoclavine, lysergic acid I. R ... 

One example where product inhibition obviously plays a role in living cells is ergoline alkaloid formation in Claviceps (D 21.2). In mycelial mats of Claviceps developing in stationary batch cultures the intracellular concentration of ergoline alkaloids and the activity of dimethylallyl-pyrophosphate L-tryptophan dimethylallyltransferase (DMAT synthase) measurable in homogenates undergo fluctuations Enzyme activity tends to decrease when the intracellular alkaloid concentration is at a maximum. This oscillation may be explained by... 

Dimethylallyl pyrophosphate L-tryptophan dimethylallyltransferase (DMAT synthase) ... 

Cress, W.A., Chayet, L.T. and Rilling, H.C. (1981) Crystallization and partial characterization of dimethylally 1 pyrophosphate L-Tryptophan Dimethylallyltransferase from Claviceps sp. SD 58. /. Biol. Chem., 256, 10917-10923. 

Dimethylallyltryptophan synthetase (systematic name dimethylallyl-pyrophosphate L-tryptophan dimethylallyltransferase) was isolated by Heinstein et al. (1971). The enzyme was purified to homogeneity from mycelia of Claviceps strain SD 58 (Lee et al., 1976). The enzyme is a single polypeptide chain with molecular weight 73,000. It is activated by... 

Different approaches have been carried out to investigate the biosynthesis of EAs. Early feeding experiments with isotope-labeled precursors, e.g., [ C]-L- tryptophan 1, to rye ears infected with C. purpurea or to fermentation cultures of different Claviceps species proved its incorporation into 2 [100-102]. Further biochemical experiments with crude and purified enzyme extracts fi om producers revealed the determinant step in the biosynthesis of EAs by the key enzyme 4-dimethylallyltransferase (4-DMATS) [103, 104], i.e., the prenylation of 1 at C-4 position [17, 104, 105]. 

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