Structural highlights
Function
[RISB_AQUAE] Catalyzes the formation of 6,7-dimethyl-8-ribityllumazine by condensation of 5-amino-6-(D-ribitylamino)uracil with 3,4-dihydroxy-2-butanone 4-phosphate. This is the penultimate step in the biosynthesis of riboflavin.[1] [2]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
6,7-Dimethyl-8-ribityllumazine is the biosynthetic precursor of riboflavin, which, as a coenzyme, plays a vital role in the electron transfer process for energy production in all cellular organisms. The enzymes involved in lumazine biosynthesis have been studied in considerable detail. However, the conclusive mechanism of the reaction catalyzed by lumazine synthase has remained unclear. Here, we report four crystal structures of the enzyme from the hyperthermophilic bacterium Aquifex aeolicus in complex with different inhibitor compounds. The structures were refined at resolutions of 1.72 A, 1.85 A, 2.05 A and 2.2 A, respectively. The inhibitors have been designed in order to mimic the substrate, the putative reaction intermediates and the final product. Structural comparisons of the native enzyme and the inhibitor complexes as well as the kinetic data of single-site mutants of lumazine synthase from Bacillus subtilis showed that several highly conserved residues at the active site, namely Phe22, His88, Arg127, Lys135 and Glu138 are most likely involved in catalysis. A structural model of the catalytic process, which illustrates binding of substrates, enantiomer specificity, proton abstraction/donation, inorganic phosphate elimination, formation of the Schiff base and cyclization is proposed.
A structure-based model of the reaction catalyzed by lumazine synthase from Aquifex aeolicus.,Zhang X, Meining W, Cushman M, Haase I, Fischer M, Bacher A, Ladenstein R J Mol Biol. 2003 Apr 18;328(1):167-82. PMID:12684006[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Haase I, Mortl S, Kohler P, Bacher A, Fischer M. Biosynthesis of riboflavin in archaea. 6,7-dimethyl-8-ribityllumazine synthase of Methanococcus jannaschii. Eur J Biochem. 2003 Mar;270(5):1025-32. PMID:12603336
- ↑ Zhang X, Meining W, Fischer M, Bacher A, Ladenstein R. X-ray structure analysis and crystallographic refinement of lumazine synthase from the hyperthermophile Aquifex aeolicus at 1.6 A resolution: determinants of thermostability revealed from structural comparisons. J Mol Biol. 2001 Mar 9;306(5):1099-114. PMID:11237620 doi:10.1006/jmbi.2000.4435
- ↑ Zhang X, Meining W, Cushman M, Haase I, Fischer M, Bacher A, Ladenstein R. A structure-based model of the reaction catalyzed by lumazine synthase from Aquifex aeolicus. J Mol Biol. 2003 Apr 18;328(1):167-82. PMID:12684006
