1kyx
From Proteopedia
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Lumazine Synthase from S.pombe bound to carboxyethyllumazine
Overview
Riboflavin is an essential cofactor in all organisms. Its direct biosynthetic precursor, 6,7-dimethyl-8-ribityllumazine, is synthesised by the enzyme 6,7-dimethyl-8-ribityllumazine synthase. Recently, we have found that the enzyme from Schizosaccharomyces pombe binds riboflavin, the final product of the pathway with a relatively high affinity with a KD of 1.2 microM. Here, we report on the crystal structure of lumazine synthase from S. pombe with bound riboflavin and compare the binding mode with those of the substrate analogue inhibitor 5-nitro-6-(D-ribitylamino)-2,4(1H,3H)-pyrimidinedione and of the product analogue 6-carboxyethyl-7-oxo-8-ribityllumazine. In all complexes the pyrimidinedione moieties of each respective ligand bind in a very similar orientation. Binding of riboflavin additionally involves a stacking interaction of the dimethylbenzene moiety with the side-chain of His94, a highly conserved residue in all lumazine synthases. The enzyme from Bacillus subtilis showed a KD of at least 1 mM whereas the very homologous enzyme from Saccharomyces cerevisiae had a comparable KD of 3.9 microM. Structural comparison of the S. cerevisiae, the S. pombe, and the mutant enzymes suggests that fine tuning of affinity is achieved by influencing this stacking interaction.
About this Structure
1KYX is a Single protein structure of sequence from Schizosaccharomyces pombe with and as ligands. Active as Riboflavin synthase, with EC number 2.5.1.9 Full crystallographic information is available from OCA.
Reference
The structural basis of riboflavin binding to Schizosaccharomyces pombe 6,7-dimethyl-8-ribityllumazine synthase., Gerhardt S, Haase I, Steinbacher S, Kaiser JT, Cushman M, Bacher A, Huber R, Fischer M, J Mol Biol. 2002 May 17;318(5):1317-29. PMID:12083520
Page seeded by OCA on Thu Feb 21 13:39:27 2008
