Details

Autor(en) / Beteiligte

• Coquille, Sandrine
• Roux, Céline
• Fitzpatrick, Teresa B.
• Thore, Stéphane

Titel

The Last Piece in the Vitamin B1 Biosynthesis Puzzle

Ist Teil von

• The Journal of biological chemistry, 2012-12, Vol.287 (50), p.42333-42343

Ort / Verlag

Elsevier Inc

Erscheinungsjahr

2012

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• Vitamin B1 is essential for all organisms being well recognized as a necessary cofactor for key metabolic pathways such as glycolysis, and was more recently implicated in DNA damage responses. Little is known about the enzyme responsible for the formation of the pyrimidine moiety (4-amino-5-hydroxymethyl-2-methylpyrimidine phosphate (HMP-P) synthase). We report a structure-function study of the HMP-P synthase from yeast, THI5p. Our crystallographic structure shows that THI5p is a mix between periplasmic binding proteins and pyridoxal 5′-phosphate-dependent enzymes. Mutational and yeast complementation studies identify the key residues for HMP-P biosynthesis as well as the use of pyridoxal 5′-phosphate as a substrate rather than as a cofactor. Furthermore, we could show that iron binding to HMP-P synthase is essential for the reaction. Background: The enzyme synthesizing the pyrimidine moiety (HMP-P synthase or THI5p) of vitamin B1 is poorly characterized. Results: We determined an atomic model of THI5p and have identified its active site using mutagenesis experiments. Conclusion: THI5p forms a dimer and uses PLP as a substrate rather than as a cofactor. Significance: Our study provides seminal information on the enzymatic mechanism of HMP-P synthase.