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Working at the membrane interface: Ligand‐induced changes in dynamic conformation and oligomeric structure in human aromatase
Author(s) -
Di Nardo Giovanna,
Cimicata Giuseppe,
Baravalle Roberta,
Dell'Angelo Valentina,
Ciaramella Alberto,
Catucci Gianluca,
Ugliengo Piero,
Gilardi Gianfranco
Publication year - 2017
Publication title -
biotechnology and applied biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.468
H-Index - 70
eISSN - 1470-8744
pISSN - 0885-4513
DOI - 10.1002/bab.1613
Subject(s) - aromatase , chemistry , molecular dynamics , ligand (biochemistry) , biophysics , protein structure , active site , substrate (aquarium) , lipid bilayer , protein dynamics , enzyme , aromatase inhibitor , biochemistry , membrane , stereochemistry , crystallography , biology , receptor , computational chemistry , ecology , genetics , cancer , breast cancer
Abstract Aromatase catalyzes the biosynthesis of estrogens from androgens. Owing to the physiological importance of this conversion of lipophilic substrates, the interaction with the lipid bilayer for this cytochrome P450 is crucial for its dynamics that must allow an easy access to substrates and inhibitors. Here, the aromatase–anastrozole interaction is studied by combining computational methods to identify possible access/egress routes with the protein inserted in the membrane and experimental tools aimed at the investigation of the effect of the inhibitor on the protein conformation. By means of molecular dynamics simulations of the protein inserted in the membrane, two channels, not detected in the starting crystal structure, are found after a 20‐nSec simulation. Trypsin digestion on the recombinant protein shows that the enzyme is strongly protected by the presence of the substrate and even more by the inhibitor. DSC experiments show an increase in the melting temperature of the protein in complex with the substrate (49.3 °C) and the inhibitor (58.7 °C) compared to the ligand‐free enzyme (45.9 °C), consistent with a decrease of flexibility of the protein. The inhibitor anastrozole enters the active site of the protein through a channel different from that used from the substrate and promotes a conformational change that stiffens the protein conformation and decreases the protein–protein interaction between different aromatase molecules.