skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Multiple Functions of Aromatic-Carbohydrate Interactions in a Processive Cellulase Examined with Molecular Simulation

Journal Article · · Journal of Biological Chemistry

Proteins employ aromatic residues for carbohydrate binding in a wide range of biological functions. Glycoside hydrolases, which are ubiquitous in nature, typically exhibit tunnels, clefts, or pockets lined with aromatic residues for processing carbohydrates. Mutation of these aromatic residues often results in significant activity differences on insoluble and soluble substrates.However, the thermodynamic basis and molecular level role of these aromatic residues remain unknown. Here, we calculate the relative ligand binding free energy by mutating tryptophans in the Trichoderma reesei family 6 cellulase (Cel6A) to alanine. Removal of aromatic residues near the catalytic site has little impact on the ligand binding free energy, suggesting that aromatic residuesimmediately upstream of the active site are not directly involved in binding, but play a role in the glucopyranose ring distortion necessary for catalysis. Removal of aromatic residues at the entrance and exit of the Cel6A tunnel, however, dramatically impacts the binding affinity, suggesting that these residues play a role in chain acquisition and product stabilization, respectively. The rolessuggested from differences in binding affinity are confirmed by molecular dynamics and normal mode analysis. Surprisingly, our results illustrate that aromatic-carbohydrate interactions vary dramatically depending on the position in the enzyme tunnel. As aromatic-carbohydrate interactions are present in all carbohydrate-active enzymes, these results have implications for understanding proteinstructure-function relationships in carbohydrate metabolism and recognition, carbon turnover in nature, and protein engineering strategies for biomass utilization. Generally, these results suggest that nature employs aromatic-carbohydrate interactions with a wide range of binding affinities for diverse functions.

Research Organization:
National Renewable Energy Laboratory (NREL), Golden, CO (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
DOE Contract Number:
AC36-08GO28308
OSTI ID:
1573191
Report Number(s):
NREL/JA-5100-52948
Journal Information:
Journal of Biological Chemistry, Vol. 286
Country of Publication:
United States
Language:
English

References (78)

Techniques for visualization of carbohydrate molecules journal November 2006
The Conformational Free Energy Landscape of β- d -Glucopyranose. Implications for Substrate Preactivation in β-Glucoside Hydrolases journal September 2007
Carbohydrate Polymers at the Center of Life’s Origins: The Importance of Molecular Processivity journal December 2008
The binding specificity and affinity determinants of family 1 and family 3 cellulose binding modules journal January 2003
Multiconfiguration thermodynamic integration journal July 1991
Automated docking to explore subsite binding by glycoside hydrolase family 6 cellobiohydrolases and endoglucanases journal November 2007
Cellulase digestibility of pretreated biomass is limited by cellulose accessibility journal January 2007
The Active Site of Cellobiohydrolase Cel6A from Trichoderma r eesei :  The Roles of Aspartic Acids D221 and D175 journal August 2002
Applications of computational science for understanding enzymatic deconstruction of cellulose journal April 2011
Examination of the α-Chitin Structure and Decrystallization Thermodynamics at the Nanoscale journal April 2011
Crystallographic evidence for substrate ring distortion and protein conformational changes during catalysis in cellobiohydrolase Ce16A from Trichoderma reesei journal September 1999
Molecular-Level Origins of Biomass Recalcitrance: Decrystallization Free Energies for Four Common Cellulose Polymorphs journal April 2011
Mechanism of initial rapid rate retardation in cellobiohydrolase catalyzed cellulose hydrolysis journal April 2010
A Simple Model System for the Study of Carbohydrate−Aromatic Interactions journal March 2007
Processivity, Synergism, and Substrate Specificity of Thermobifida fusca Cel6B journal September 2009
Importance of Exposed Aromatic Residues in Chitinase B from Serratia marcescens 2170 for Crystalline Chitin Hydrolysis journal August 2004
High Speed Atomic Force Microscopy Visualizes Processive Movement of Trichoderma reesei Cellobiohydrolase I on Crystalline Cellulose journal October 2009
Biomass Recalcitrance: Engineering Plants and Enzymes for Biofuels Production journal February 2007
Conformational analysis of the anomeric forms of sophorose, laminarabiose, and cellobiose using MM3 journal September 1992
Monte Carlo Simulations book September 2002
All-Atom Empirical Potential for Molecular Modeling and Dynamics Studies of Proteins journal April 1998
Harmonic dynamics of proteins: normal modes and fluctuations in bovine pancreatic trypsin inhibitor. journal November 1983
Additive empirical force field for hexopyranose monosaccharides journal November 2008
Molecular Recognition of Saccharides by Proteins. Insights on the Origin of the Carbohydrate−Aromatic Interactions
  • Fernández-Alonso, María del Carmen; Cañada, Francisco Javier; Jiménez-Barbero, Jesús
  • Journal of the American Chemical Society, Vol. 127, Issue 20 https://doi.org/10.1021/ja051020+
journal April 2005
The Carbohydrate-Active EnZymes database (CAZy): an expert resource for Glycogenomics journal January 2009
CHARMM: The biomolecular simulation program journal July 2009
Puckering Coordinates of Monocyclic Rings by Triangular Decomposition journal March 2007
Chemical Biology of the Sugar Code journal May 2004
Sweet spots in functional glycomics journal April 2006
Deconstruction of Lignocellulosic Biomass to Fuels and Chemicals journal July 2011
Stereochemical course of hydrolysis and hydration reactions catalysed by cellobiohydrolases I and II from Trichoderma reesei journal April 1990
The three-dimensional crystal structure of the catalytic core of cellobiohydrolase I from Trichoderma reesei journal July 1994
Visualisation of cyclic and multi-branched molecules with VMD journal September 2009
Computational simulations of the Trichoderma reesei cellobiohydrolase I acting on microcrystalline cellulose Iβ: the enzyme–substrate complex journal October 2009
Aromatic-Carbohydrate Interactions: An NMR and Computational Study of Model Systems journal August 2008
Restructuring the Crystalline Cellulose Hydrogen Bond Network Enhances Its Depolymerization Rate journal July 2011
Carbohydrate recognition systems: functional triads in cell—cell interactions journal October 1996
Probing Carbohydrate Product Expulsion from a Processive Cellulase with Multiple Absolute Binding Free Energy Methods journal March 2011
Quantum Mechanics/Molecular Mechanics Modeling of Substrate-Assisted Catalysis in Family 18 Chitinases: Conformational Changes and the Role of Asp142 in Catalysis in ChiB journal May 2011
Evolutionary considerations in relating oligosaccharide diversity to biological function journal August 1999
Enthalpic Nature of the CH/π Interaction Involved in the Recognition of Carbohydrates by Aromatic Compounds, Confirmed by a Novel Interplay of NMR, Calorimetry, and Theoretical Calculations
  • Ramírez-Gualito, Karla; Alonso-Ríos, Rosa; Quiroz-García, Beatriz
  • Journal of the American Chemical Society, Vol. 131, Issue 50 https://doi.org/10.1021/ja903950t
journal December 2009
Imaging the Enzymatic Digestion of Bacterial Cellulose Ribbons Reveals the Endo Character of the Cellobiohydrolase Cel6A from Humicola insolens and Its Mode of Synergy with Cellobiohydrolase Cel7A journal April 2000
Extending the treatment of backbone energetics in protein force fields: Limitations of gas-phase quantum mechanics in reproducing protein conformational distributions in molecular dynamics simulations journal August 2004
Aromatic residues within the substrate-binding cleft of Bacillus circulans chitinase A1 are essential for hydrolysis of crystalline chitin journal November 2003
Engineering the Exo-loop of Trichoderma reesei Cellobiohydrolase, Cel7A. A comparison with Phanerochaete chrysosporium Cel7D journal October 2003
Lectins:  Carbohydrate-Specific Proteins That Mediate Cellular Recognition journal April 1998
Glycoarrays—tools for determining protein–carbohydrate interactions and glycoenzyme specificity journal January 2008
General definition of ring puckering coordinates journal March 1975
Stereochemical course of the action of the cellobioside hydrolases I and II of Trichoderma reesei journal January 1988
Carbohydrate-binding modules: fine-tuning polysaccharide recognition journal September 2004
Determination of substrate binding energies in individual subsites of a family 18 chitinase journal October 2010
Three-dimensional structure of cellobiohydrolase II from Trichoderma reesei journal July 1990
Protein–carbohydrate interactions: learning lessons from nature journal September 2001
Conformational analysis of chitobiose and chitosan journal February 1994
Siglecs and their roles in the immune system journal April 2007
Costs and benefits of processivity in enzymatic degradation of recalcitrant polysaccharides journal November 2006
Clusters, bundles, arrays and lattices: novel mechanisms for lectin–saccharide-mediated cellular interactions journal October 2002
Identification of Amino Acids Responsible for Processivity in a Family 1 Carbohydrate-Binding Module from a Fungal Cellulase journal January 2010
Evaluation of a carbohydrate–π interaction in a peptide model system journal January 2007
Structure and function of Humicola insolens family 6 cellulases: structure of the endoglucanase, Cel6B, at 1.6 Å resolution journal May 2000
IR-Spectral Signatures of Aromatic–Sugar Complexes: Probing Carbohydrate–Protein Interactions journal May 2007
Tryptophan 272: an essential determinant of crystalline cellulose degradation by Trichoderma reesei cellobiohydrolase Cel6A journal June 1998
CHARMM Additive All-Atom Force Field for Glycosidic Linkages between Hexopyranoses journal August 2009
Decrystallization of Oligosaccharides from the Cellulose Iβ Surface with Molecular Simulation journal June 2011
Carbohydrate−π Interactions: What Are They Worth? journal November 2008
Structural Basis of Lectin-Carbohydrate Recognition journal June 1996
Mapping glycoside hydrolase substrate subsites by isothermal titration calorimetry journal July 2004
Structure of a two-domain chitotriosidase from Serratia marcescens at 1.9-A resolution journal May 2000
CHARMM Additive All-Atom Force Field for Carbohydrate Derivatives and Its Utility in Polysaccharide and Carbohydrate–Protein Modeling journal August 2011
Dissecting factors that contribute to ligand-binding energetics for family 18 chitinases journal November 2010
Effect of glycosylation on protein folding: A close look at thermodynamic stabilization journal June 2008
Processivity of Cellobiohydrolases Is Limited by the Substrate journal November 2010
How the walls come crumbling down: recent structural biochemistry of plant polysaccharide degradation journal June 2008
Statistical Mechanics of Fluid Mixtures journal May 1935
VMD: Visual molecular dynamics journal February 1996
Free energy calculations: Applications to chemical and biochemical phenomena journal November 1993
Surface Plasmon Resonance Imaging Studies of Protein-Carbohydrate Interactions journal May 2003
Structure and function of Humicola insolens family 6 cellulases: structure of the endoglucanase, Cel6B, at 1.6 Å resolution journal May 2000