Details

Autor(en) / Beteiligte

• Yazdani, Mohammad
• Zallot, Rémi
• Tunc-Ozdemir, Meral
• de Crécy-Lagard, Valérie
• Shintani, David K.
• Hanson, Andrew D.

Titel

Identification of the thiamin salvage enzyme thiazole kinase in Arabidopsis and maize

Ist Teil von

• Phytochemistry (Oxford), 2013-10, Vol.94, p.68-73

Ort / Verlag

England: Elsevier Ltd

Erscheinungsjahr

2013

Quelle

MEDLINE

Beschreibungen/Notizen

• Plants, like microorganisms, can salvage the thiazole moiety of thiamin for reuse in thiamin synthesis. Plant genes encoding the key salvage enzyme thiazole kinase were identified by genomics, genetics, and biochemistry. •Plants can salvage the thiazole moiety of thiamin for reuse in thiamin synthesis.•Comparative genomics was used to predict genes for the salvage enzyme thiazole kinase.•The predictions were validated by bacterial complementation and enzyme assays.•Knocking out the predicted Arabidopsis gene resulted in defective thiazole salvage. The breakdown of thiamin (vitamin B1) and its phosphates releases a thiazole moiety, 4-methyl-5-(2-hydroxyethyl)thiazole (THZ), that microorganisms and plants are able to salvage for re-use in thiamin synthesis. The salvage process starts with the ATP-dependent phosphorylation of THZ, which in bacteria is mediated by ThiM. The Arabidopsis and maize genomes encode homologs of ThiM (At3g24030 and GRMZM2G094558, respectively). Plasmid-driven expression of either plant homolog restored the ability of THZ to rescue Escherichia coli thiM deletant strains, showing that the plant proteins have ThiM activity in vivo. Enzymatic assays with purified recombinant proteins confirmed the presence of THZ kinase activity. Furthermore, ablating the Arabidopsis At3g24030 gene in a thiazole synthesis mutant severely impaired rescue by THZ. Collectively, these results show that ThiM homologs are the main source of THZ kinase activity in plants and are consequently crucial for thiamin salvage.