Structure of the Thiazole Biosynthetic Enzyme THI1 from Arabidopsis thaliana

Carlos F.M Menck,Glaucius Oliva,Marie-Anne Van Sluys,Paulo H.C Godoi,Rodrigo S Galhardo,Douglas D Luche

doi:10.1074/jbc.m604469200

Abstract

Thiamin pyrophosphate is an essential coenzyme in all organisms that depend on fermentation, respiration or photosynthesis to produce ATP. It is synthesized through two independent biosynthetic routes: one for the synthesis of 2-methyl-4-amino-5-hydroxymethylpyrimidine pyrophosphate (pyrimidine moiety) and another for the synthesis of 4-methyl-5-(beta-hydroxyethyl) thiazole phosphate (thiazole moiety). Herein, we will describe the three-dimensional structure of THI1 protein from Arabidopsis thaliana determined by single wavelength anomalous diffraction to 1.6A resolution. The protein was produced using heterologous expression in bacteria, unexpectedly bound to 2-carboxylate-4-methyl-5-beta-(ethyl adenosine 5-diphosphate) thiazole, a potential intermediate of the thiazole biosynthesis in Eukaryotes. THI1 has a topology similar to dinucleotide binding domains and although details concerning its function are unknown, this work provides new clues about the thiazole biosynthesis in Eukaryotes.

Highlights

In Beriberi and the Wernicke-Korsakoff syndrome, severe conditions that involve damage to the cardiovascular, muscular, gastrointestinal, and nervous systems [2]
THI1 Structure in Complex with a Putative Thiazole Biosynthesis Intermediate—The molecular events leading to the biosynthesis of thiazole and pyrimidine moieties of thiamine remain to be understood in Eukaryotes
THI1 homologues are the only known enzymes to take part in the thiazole biosynthesis in a diversity of unicellular organisms belonging to Archaea and some Fungi, as well as highly organized multicellular organisms, such as Plantae

Summary

Introduction

In Beriberi and the Wernicke-Korsakoff syndrome, severe conditions that involve damage to the cardiovascular, muscular, gastrointestinal, and nervous systems [2]. It is clear that THI1 cannot bind FAD due to a limited space to accommodate its isoalloxazine extremity, while recent evidence has shown that the yeast orthologue Thi4 protein possesses a NAD-binding site [36], a result that we have recently confirmed for Ligand Binding Site—The structure of THI1 reveals the presence of a ligand not previously described, observed in the region where a bound dinucleotide was expected.

Results

Conclusion