The biosynthesis of the thiazole phosphate moiety of thiamin (vitamin B1): the early steps catalyzed by thiazole synthase.
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.
Dorrestein
Pieter C
PC
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA.
Zhai
Huili
H
Taylor
Sean V
SV
McLafferty
Fred W
FW
Begley
Tadhg P
TP
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000201:enzymology; D002384:Catalysis; D041961:Deuterium Exchange Measurement; D007097:Imines / Q000378:metabolism; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010755:Organophosphates / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010428:Pentosephosphates / Q000378:metabolism*; D013831:Thiamine / Q000096:biosynthesis*; D013844:Thiazoles / Q000378:metabolism*; D014166:Transferases / Q000378:metabolism*
C109460:1-deoxylulose 5-phosphate; D007097:Imines; D010755:Organophosphates; D010428:Pentosephosphates; D013844:Thiazoles; D014166:Transferases; C109461:deoxyxylulose-5-phosphate synthase; D010100:Oxygen; D013831:Thiamine