The Biosynthesis of the Thiazole Phosphate Moiety of Thiamin (Vitamin B1):  The Early Steps Catalyzed by Thiazole Synthase

• Published in: Journal of the American Chemical Society Vol. 126; no. 10; pp. 3091 - 3096
• Main Authors: Dorrestein, Pieter C, Huili, Taylor, Sean V, McLafferty, Fred W, Begley, Tadhg P
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 17.03.2004
• Subjects: Amino Acid Sequence; Analytical, structural and metabolic biochemistry; Bacillus subtilis - enzymology; Biological and medical sciences; Catalysis; Chemistry; Coenzymes, vitamins; Deuterium Exchange Measurement; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Heterocyclic compounds; Heterocyclic compounds with n hetero atom and also o and/or s, se, te hetero atoms; Imines - metabolism; Molecular Sequence Data; Nuclear Magnetic Resonance, Biomolecular; Organic chemistry; Organophosphates - metabolism; Other biological molecules; Oxygen - metabolism; Pentosephosphates - metabolism; Preparations and properties; Thiamine - biosynthesis; Thiazoles - metabolism; Transferases - metabolism; Sulfur nitrogen heterocycle; Five membered ring; Catalytic reaction; Isotope exchange; Enzymatic catalysis; Amadori rearrangement; Biosynthesis; NMR spectrometry; Carbon 13; Thiamine; Structural analysis
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja039616p

Thiazole synthase (ThiG) catalyzes an Amadori-type rearrangement of 1-deoxy-d-xylulose-5-phosphate (DXP) via an imine intermediate. In support of this, we have demonstrated enzyme-catalyzed exchange of the C2 carbonyl of DXP. Borohydride reduction of the enzyme DXP imine followed by top-down mass spectrometric analysis localized the imine to lysine 96. On the basis of these observations, a new mechanism for the biosynthesis of the thiazole phosphate moiety of thiamin pyrophosphate in Bacillus subtilis is proposed. This mechanism involves the generation of a ketone at C3 of DXP by an Amadori-type rearrangement of the imine followed by nucleophillic addition of the sulfur carrier protein (ThiS-thiocarboxylate) to this carbonyl group.