3nt5 | pdb_00003nt5
Crystal structure of myo-inositol dehydrogenase from Bacillus subtilis with bound cofactor and product inosose
Structural highlights
FunctionIOLG_BACSU Involved in the oxidation of myo-inositol (MI) and D-chiro-inositol (DCI) to 2-keto-myo-inositol (2KMI or 2-inosose) and 1-keto-D-chiro-inositol (1KDCI), respectively. Can also use D-glucose and D-xylose, and shows a trace of activity with D-ribose and D-fructose.[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 PubMedInositol dehydrogenase from Bacillus subtilis (BsIDH) is a NAD+-dependent enzyme that catalyses the oxidation of the axial hydroxyl group of myo-inositol to form scyllo-inosose. We have determined the crystal structures of wild type BsIDH and of the inactive K97V mutant in apo-, holo- and ternary complexes with inositol and inosose. BsIDH is a tetramer, with a novel arrangement consisting of 2 long continuous beta-sheets, formed from all 4 monomers, in which the central 2 strands are crossed over to form the core of the tetramer. Each subunit in the tetramer consists of two domains, an N-terminal Rossmann fold domain containing the cofactor-binding site, and a C-terminal domain containing the inositol-binding site. Structural analysis allowed us to determine residues important in cofactor and substrate binding. Lys97, Asp172, and His176 are the catalytic triad involved in the catalytic mechanism of BsIDH similar to what has been proposed for related enzymes and short chain dehydrogenases. Furthermore, a conformational change in the nicotinamide ring was observed in some ternary complexes, suggesting hydride transfer to the si-face of NAD+. Finally, comparison of the structure and sequence of BsIDH with other putative inositol dehydrogenases allowed us to differentiate these enzymes in four sub-families based on 6 consensus sequence motifs defining the cofactor- and substrate-binding sites. Structural investigation of myo-inositol dehydrogenase from Bacillus subtilis: implications for catalytic mechanism and inositol dehydrogenase subfamily classification.,van Straaten KE, Zheng H, Palmer DR, Sanders DA Biochem J. 2010 Sep 1. PMID:20809899[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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