[Gramene] Thiamine biosynthesis

[Goyer, Aymeric]

Please provide your area of interest and pathway feedback

Solanum tuberosum thiamine biosynthesis

There are two errors in this pathway because the described pathway is based on data from E. coli that do not reflect what is happening in plants.

First, it shows conversion of thiamine monophosphate to thiamine diphosphate, but this reaction does not occur in plants (for a Review see Goyer 2010 Phytochemistry 71, 1615-1624). Instead thiamine monophosphate is dephosphorylated to thiamine by a yet-to-be-characterized enzyme, then pyrophosphorylated by thiamine pyrophosphokinase (see Ajjawai et al 2007 Plant Mol Biol 65, 151-162).

Second, 4-methyl-5-hydroxyethylthiazole phosphate is not synthesized from deoxy-xylulose-5-phosphate in plants but from NAD, glycine, and a sulfur donor (a cysteine located on the enzyme 4-methyl-5-hydroxyethylthiazole phosphate synthase - see Chatterjee et al 2011 Nature).

Hope this helps.

Aymeric

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