dc.contributor.authorTankrathok, Anupong
dc.contributor.authorIglesias-Fernández, Javier
dc.contributor.authorLuang, Sukanya
dc.contributor.authorRobinson, Robert Charles
dc.contributor.authorKimura, Atsuo
dc.contributor.authorRovira, Carme
dc.contributor.authorHrmova, Maria
dc.contributor.authorKetudat Cairns, James R.
dc.identifier.citationTankrathok, A., Iglesias-Fernández, J., Luang, S., Robinson, R. C., Kimura, A., Rovira, C., et al. (2013). Structural analysis and insights into the glycon specificity of the rice GH1 Os7BGlu26 β-D-mannosidase. Acta Crystallographica Section D Biological Crystallography, 69(10), 2124-2135.en_US
dc.description.abstractRice Os7BGlu26 is a GH1 family glycoside hydrolase with a threefold higher kcat/Km value for 4-nitrophenyl β-D-mannoside (4NPMan) compared with 4-nitrophenyl β-D-glucoside (4NPGlc). To investigate its selectivity for β-D-mannoside and β-D-glucoside substrates, the structures of apo Os7BGlu26 at a resolution of 2.20 Å and of Os7BGlu26 with mannose at a resolution of 2.45 Å were elucidated from isomorphous crystals in space group P212121. The (β/α)8-barrel structure is similar to other GH1 family structures, but with a narrower active-site cleft. The Os7BGlu26 structure with D-mannose corresponds to a product complex, with β-D-mannose in the 1S5 skew-boat conformation. Docking of the 1S3, 1S5, 2SO and 3S1 pyranose-ring conformations of 4NPMan and 4NPGlc substrates into the active site of Os7BGlu26 indicated that the lowest energies were in the 1S5 and 1S3 skew-boat conformations. Comparison of these docked conformers with other rice GH1 structures revealed differences in the residues interacting with the catalytic acid/base between enzymes with and without β-­D-­mannosidase activity. The mutation of Tyr134 to Trp in Os7BGlu26 resulted in similar kcat/Km values for 4NPMan and 4NPGlc, while mutation of Tyr134 to Phe resulted in a 37-fold higher kcat/Km for 4NPMan than 4NPGlc. Mutation of Cys182 to Thr decreased both the activity and the selectivity for β-D-mannoside. It was concluded that interactions with the catalytic acid/base play a significant role in glycon selection.en_US
dc.description.sponsorshipASTAR (Agency for Sci., Tech. and Research, S’pore)en_US
dc.relation.ispartofseriesActa Crystallographica Section D Biological Crystallographyen_US
dc.rights© 2013 International Union of Crystallography.en_US
dc.subjectStructural analysisen_US
dc.subjectGlycoside hydrolasesen_US
dc.titleStructural analysis and insights into the glycon specificity of the rice GH1 Os7BGlu26 β-D-mannosidaseen_US
dc.typeJournal Article
dc.contributor.schoolSchool of Biological Sciencesen_US

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