Biosynthesis of vitamin B2: Structure and mechanism of riboflavin synthase.
The biosynthesis of one riboflavin molecule requires one molecule of GTP and two molecules of ribulose 5-phosphate as substrates. GTP is hydrolytically opened, converted into 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione by a sequence of deamination, side chain reduction and dephosphorylation. Condensation with 3,4-dihydroxy-2-butanone 4-phosphate obtained from ribulose 5-phosphate leads to 6,7-dimethyl-8-ribityllumazine. The final step in the biosynthesis of the vitamin involves the dismutation of 6,7-dimethyl-8-ribityllumazine catalyzed by riboflavin synthase. The mechanistically unusual reaction involves the transfer of a four-carbon fragment between two identical substrate molecules. The second product, 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione, is recycled in the biosynthetic pathway by 6,7-dimethyl-8-ribityllumazine synthase. This article will review structures and reaction mechanisms of riboflavin synthases and related proteins up to 2007 and 122 references are cited.
Fischer
Markus
M
Institute of Food Chemistry, University of Hamburg, Grindelallee 117, D-20146 Hamburg, Germany. markus.fischer@uni-hamburg.de
Bacher
Adelbert
A
D000595:Amino Acid Sequence; D001105:Archaea / Q000378:metabolism; D001419:Bacteria / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017510:Protein Folding; D012256:Riboflavin / Q000096:biosynthesis* / Q000737:chemistry; D012258:Riboflavin Synthase / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
D012258:Riboflavin Synthase; D012256:Riboflavin