The Energy Landscape for the Interaction of the Family 1 Carbohydrate-Binding Module and the Cellulose Surface is Altered by Hydrolyzed Glycosidic Bonds

• Published in: The journal of physical chemistry. B 2009-08, Vol.113 (31), p.10994-11002
• Main Authors: Bu, Lintao, Beckham, Gregg T, Crowley, Michael F, Chang, Christopher H, Matthews, James F, Bomble, Yannick J, Adney, William S, Himmel, Michael E, Nimlos, Mark R
• Format: Article
• Language: English
• Subjects: 09 BIOMASS FUELS; B: Biophysical Chemistry; BASIC BIOLOGICAL SCIENCES; Bioenergy; CELLOBIOSE; CELLULASE; CELLULOSE; Cellulose - chemistry; Cellulose - metabolism; Cellulose 1,4-beta-Cellobiosidase - chemistry; Cellulose 1,4-beta-Cellobiosidase - metabolism; CHAINS; Chemical and Biosciences; Computational Sciences; ENZYMES; FREE ENERGY; GLUCOSE; HYDROLYSIS; Hydrophobic and Hydrophilic Interactions; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; Materials Science and Semiconductors; Models, Molecular; Molecular Conformation; SIMULATION; STABILITY; THERMODYNAMICS; Trichoderma - enzymology; TRICHODERMA VIRIDE
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp904003z

A multiscale simulation model is used to construct potential and free energy surfaces for the carbohydrate-binding module [CBM] from an industrially important cellulase, Trichoderma reesei cellobiohydrolase I, on the hydrophobic face of a coarse-grained cellulose Iβ polymorph. We predict from computation that the CBM alone exhibits regions of stability on the hydrophobic face of cellulose every 5 and 10 Å, corresponding to a glucose unit and a cellobiose unit, respectively. In addition, we predict a new role for the CBM: specifically, that in the presence of hydrolyzed cellulose chain ends, the CBM exerts a thermodynamic driving force to translate away from the free cellulose chain ends. This suggests that the CBM is not only required for binding to cellulose, as has been known for two decades, but also that it has evolved to both assist the enzyme in recognizing a cellulose chain end and exert a driving force on the enzyme during processive hydrolysis of cellulose.