Tyrosine thiamin biosynthesis

In plants, little is known about the basic building blocks and the reactions involved in thiamine biosynthesis. An early study with chloroplasts of spinach indicated that 1-deoxy-D-xylulose 5-phosphate, tyrosine, and cysteine act as precursors of the thiazole moiety in analogy to the pathway in E. coli. More recently, it has been shown that a homolog of the THIC protein that converts 5-aminoimidazole ribotide into 38 is essential (25). These results suggest that the plant pathway is similar to the pathway in prokaryotes but not to that in yeast. 

S ATP + 4-methyl-5-(2-hydroxyethyl)thiazole <1, 2> (<1> enzyme involved in biosynthesis of thiamine [1] <1> the bifunctioinal enzyme hydroxyethylthiazole kinase/thiamine-phosphate pyrophosphorylase catalyzes two sequential steps in the synthesis of thiamin monophosphate from hydroxyethylthiazole [2] <2> the enzyme is a salvage enzyme in the thiamin biosynthetic pathway and enables the cell to use recycled 4-methyl-5-j8-hydroxyethylthiazole as an alternative to its synthesis from 1-deoxy-o-xylulose-5-phosphate, cysteine, and tyrosine [3]) (Reversibility <1, 2> [1,2,3]) [1,2, 3]... 

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