Molecular Dynamics Simulation and Site-Directed Mutagenesis of Alcohol Acyltransferase: A Proposed Mechanism of Catalysis

Morales-Quintana, L; Nunez-Tobar, MX; Moya-Leon, MA; Herrera R.

Abstract

Aroma in Vasconcellea pubescens fruit is determined by esters, which are the products of catalysis by alcohol acyltransferase (VpAAT1). VpAAT1 protein structure displayed the conserved HxxxD motif facing the solvent channel in the center of the structure. To gain insight into the role of these catalytic residues, kinetic and site-directed mutagenesis studies were carried out in VpAAT1 protein. Based on dead-end inhibition studies, the kinetic could be described in terms of a ternary complex mechanism with the H166 residue as the catalytic base. Kinetic results showed the lowest Km value for hexanoyl-CoA. Additionally, the most favorable predicted substrate orientation was observed for hexanoyl-CoA, showing a coincidence between kinetic studies and molecular docking analysis. Substitutions H166A, D170A, D170N, and D170E were evaluated in silico. The solvent channel in all mutant structures was lost, showing large differences with the native structure. Molecular docking and molecular dynamics simulations were able to describe unfavored energies for the interaction of the mutant proteins with different alcohols and acyl-CoAs. Additionally, in vitro site-directed mutagenesis of H166 and D170 in VpAAT1 induced a loss of activity, confirming the functional role of both residues for the activity, H166 being directly involved in catalysis.

Más información

Título según WOS: Molecular Dynamics Simulation and Site-Directed Mutagenesis of Alcohol Acyltransferase: A Proposed Mechanism of Catalysis
Título según SCOPUS: Molecular dynamics simulation and site-directed mutagenesis of alcohol acyltransferase: A proposed mechanism of catalysis
Título de la Revista: JOURNAL OF CHEMICAL INFORMATION AND MODELING
Volumen: 53
Número: 10
Editorial: AMER CHEMICAL SOC
Fecha de publicación: 2013
Página de inicio: 2689
Página final: 2700
Idioma: English
URL: http://pubs.acs.org/doi/abs/10.1021/ci400409s
DOI:

10.1021/ci400409s

Notas: ISI, SCOPUS