Enthalpically-driven ligand recognition and cavity solvation of bovine odorant binding protein
Por:
Gomez-Velasco, Homero, Rojo-Dominguez, Arturo, Garcia-Hernandez, Enrique
Publicada:
1 ene 2020
Resumen:
Lipocalins are a widely distributed family of extracellular proteins typically involved in the transport of small hydrophobic molecules. To gain new insights into the molecular basis that governs ligand recognition by this ancient protein family, the binding properties of the domain-swapped dimer bovine odorant binding protein (bOBP) and its monomeric mutant bOBP121G+ were characterized using calorimetric techniques and molecular dynamics simulations. Thermal unfolding profiles revealed that the isolated bOBP subunits behave as a cooperative folding unit. In addition, bOBP and bOBP121G+ exhibited similar ligand binding properties, characterized by a non-classical hydrophobic effect signature. The energetic differences in the binding of bOBP to 1-hexen-3-ol and the physiological ligand 1-octen-3-ol were strikingly larger than those observed for the interaction of other lipocalins with congeneric ligands. MD simulations revealed that the recurrent opening of transient pores in the submicrosecond timescale allows a profuse exchange of water molecules between the protein interior and the surrounding solvent. This picture contrasts with other lipocalins whose ligand-free binding cavities are devoid of solvent molecules. Furthermore, the simulations indicated that internal water molecules solvate the protein cavity suboptimally, forming fewer hydrogen bonds and having lower density and higher potential energy than bulk water molecules. Upon ligand occupation, water molecules were displaced from the binding cavity in an amount that depended on the ligand size. Taken together, calorimetric and MD-simulation results are consistent with a significant contribution of cavity desolvation to the enthalpically-driven interaction of bOBP with its hydrophobic ligands. © 2019 Elsevier B.V.
Filiaciones:
Gomez-Velasco, Homero:
Universidad Nacional Autónoma de México, Instituto de Química, Ciudad Universitaria, Ciudad de México, 04510, Mexico
Univ Nacl Autonoma Mexico, Inst Quim, Ciudad Univ, Mexico City 04510, DF, Mexico
Rojo-Dominguez, Arturo:
Universidad Autónoma Metropolitana, Unidad Cuajimalpa, Departamento de Ciencias Naturales, Mexico
Univ Autonoma Metropolitana, Unidad Cuajimalpa, Dept Ciencias Nat, Mexico City, DF, Mexico
Garcia-Hernandez, Enrique:
Universidad Nacional Autónoma de México, Instituto de Química, Ciudad Universitaria, Ciudad de México, 04510, Mexico
Univ Nacl Autonoma Mexico, Inst Quim, Ciudad Univ, Mexico City 04510, DF, Mexico
|