title: Molecular Dynamics Driven Design of pH-Stabilized Mutants of MNEI, a Sweet Protein.
abstract: MNEI is a single chain derivative of monellin, a plant protein that can interact with the human sweet taste receptor, being therefore perceived as sweet. This unusual physiological activity makes MNEI a potential template for the design of new sugar replacers for the food and beverage industry. Unfortunately, applications of MNEI have been so far limited by its intrinsic sensitivity to some pH and temperature conditions, which could occur in industrial processes. Changes in physical parameters can, in fact, lead to irreversible protein denaturation, as well as aggregation and precipitation. It has been previously shown that the correlation between pH and stability in MNEI derives from the presence of a single glutamic residue in a hydrophobic pocket of the protein. We have used molecular dynamics to study the consequences, at the atomic level, of the protonation state of such residue and have identified the network of intramolecular interactions responsible for MNEI stability at acidic pH. Based on this information, we have designed a pH-independent, stabilized mutant of MNEI and confirmed its increased stability by both molecular modeling and experimental techniques.
authors.affiliation: Department of Chemical Sciences, University of Naples Federico II, Naples, Italy.
authors.forename: Serena
authors.identifier: http://orcid.org/0000-0003-4787-0882
authors.initials: S
authors.lastname: Leone
authors.affiliation: Department of Chemical Sciences, University of Naples Federico II, Naples, Italy.
authors.forename: Delia
authors.initials: D
authors.lastname: Picone
mesh_terms: D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D050505:Mutant Proteins; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics; D055550:Protein Stability; D011994:Recombinant Proteins; D013549:Sweetening Agents / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D050505:Mutant Proteins; D010940:Plant Proteins; D011994:Recombinant Proteins; D013549:Sweetening Agents