Carbohydrate-receptor interactions are an integral part of biological events. They play an important role in many cellular processes, such as cell-cell adhesion, cell differentiation and in-cell signaling. Carbohydrates can interact with a receptor by using several types of intermolecular interactions. One of the most important is the interaction of a carbohydrate's apolar part with aromatic amino acid residues, known as dispersion interaction or CH/π interaction. In the study presented here, we attempted for the first time to quantify how the CH/π interaction contributes to a more general carbohydrate-protein interaction. We used a combined experimental approach, creating single and double point mutants with high level computational methods, and applied both to Ralstonia solanacearum (RSL) lectin complexes with α-L-Me-fucoside. Experimentally measured binding affinities were compared with computed carbohydrate-aromatic amino acid residue interaction energies. Experimental binding affinities for the RSL wild type, phenylalanine and alanine mutants were -8.5, -7.1 and -4.1 kcal x mol(-1), respectively. These affinities agree with the computed dispersion interaction energy between carbohydrate and aromatic amino acid residues for RSL wild type and phenylalanine, with values -8.8, -7.9 kcal x mol(-1), excluding the alanine mutant where the interaction energy was -0.9 kcal x mol(-1). Molecular dynamics simulations show that discrepancy can be caused by creation of a new hydrogen bond between the α-L-Me-fucoside and RSL. Observed results suggest that in this and similar cases the carbohydrate-receptor interaction can be driven mainly by a dispersion interaction.

• MeSH
• Amino Acids, Aromatic chemistry   genetics   metabolism   MeSH
• Bacterial Proteins chemistry   genetics   metabolism   MeSH
• Fucose chemistry   metabolism   MeSH
• Protein Conformation MeSH
• Carbohydrate Conformation MeSH
• Crystallography, X-Ray MeSH
• Lectins chemistry   genetics   metabolism   MeSH
• Models, Molecular * MeSH
• Mutation MeSH
• Proteins chemistry   genetics   metabolism   MeSH
• Ralstonia solanacearum genetics   metabolism   MeSH
• Carbohydrates chemistry   MeSH
• Protein Structure, Secondary MeSH
• Protein Structure, Tertiary MeSH
• Thermodynamics MeSH
• Protein Binding MeSH
• Binding Sites MeSH
• Hydrogen Bonding MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Amino Acids, Aromatic MeSH
• Bacterial Proteins MeSH
• Fucose MeSH
• Lectins MeSH
• Proteins MeSH
• Carbohydrates MeSH