Structural insights into the substrate recognition properties of beta-glucosidase

Abstract

Glucosidase enzymes (EC 3.2.1-3.2.3) hydrolyze sugars and are implicated in a wide spectrum of biological processes. Recently we reported that beta-glucosidase has varied kinetic parameters for the natural and synthetic substrates [K.H Nam. S.J. Kim, M.Y. Kim, J.H. Kim, T.S. Yeo, C.M. Lee, H.K Jun, K.Y. Hwang. Crystal structure of engineered beta-glucosidase from a soil metagenome, Proteins 73 (2009) 798-793]. However, an understanding of the kinetic values of beta-glucosidase has not yet enabled the elucidation of its molecular function. Here, we report the X-ray crystal structure of beta-glucosidase with a glucose and cellobiose fragment from uncultured soil metagenome. From the various crystals, we obtained the pre-reaction (native). intermediate (disaccharide cleavage) and post-reaction (glucose binding) states of the active site pocket. These structures provide snapshot of the catalytic processing of beta-glucosidase. In addition, the intermediate state of the crystal structure provides insight into the substrate specificity of beta-glucosidase. These structural studies will facilitate elucidation of the architctural mechanism responsible for the substrate recognition of beta-glucosidase. (C) 2009 Elsevier Inc. All rights reserved.