The Molecular Basis of Pharmacological Chaperoning in Human α-Galactosidase

Abstract

Summary Fabry disease patients show a deficiency in the activity of the lysosomal enzyme α-galactosidase (α-GAL or α-Gal A). One proposed treatment for Fabry disease is pharmacological chaperone therapy, where a small molecule stabilizes the α-GAL protein, leading to increased enzymatic activity. Using enzyme kinetics, tryptophan fluorescence, circular dichroism, and proteolysis assays, we show that the pharmacological chaperones 1-deoxygalactonojirimycin (DGJ) and galactose stabilize the human α-GAL glycoprotein. Crystal structures of complexes of α-GAL and chaperones explain the molecular basis for the higher potency of DGJ over galactose. Using site directed mutagenesis, we show the higher potency of DGJ results from an ionic interaction with D170. We propose that protonation of D170 in acidic conditions leads to weaker binding of DGJ. The results establish a biochemical basis for pharmacological chaperone therapy applicable to other protein misfolding diseases.

Structural Basis of Pharmacological Chaperoning for Human β-Galactosidase

“…1), a mimic of galactose, and some derivatives have been well studied as PCs for these LSDs (15,16). However, DGJ has promiscuity for a number of galactopyranoside-processing isoenzymes, which may hamper clinical development.…”

Structure and Catalytic Mechanism of a Glycoside Hydrolase Family-127 β-L-Arabinofuranosidase (HypBA1)

“…It reveals that N-domain (colored in green, broken square) of HypBA1 displays structural similarity to C-terminal domains of xyloglucanase (GH44, colored in cyan), human α-galactosidase (GH27, colored in magenta), β-xylosidase (GH39, colored in yellow) and α-L-rhamnosidase (GH78, colored in orange) with RMSD of 3.0 Å (512 Cα atoms with 14% sequence identity), 3.5 Å (390 Cα atoms with 10% sequence identity), 2.6 Å (501 Cα atoms with 10% sequence identity) and 2.8 Å (1029 Cα atoms with 9% sequence identity), respectively [29][30][31][32]. On the other hand, C-domain (colored in green, broken square) of HypBA1 shows structural similarity to N-terminal domain of ErbB4 kinase (colored in cyan) and LKB1 (colored in salmon) with RMSD of 2.6 Å (274 Cα atoms with 4% sequence identity) and 3.5 Å (311 Cα atoms with 15% sequence identity), respectively [33,34] (SI Figure S1).…”

Les chaperons pharmacologiques

“…Conclusions et perspectives thérapeutiques des chaperons pharmacologiques Le chlorhydrate de migalastat est un sucre iminé ayant une grande affinité pour le site actif de l'α-galactosidase A [9]. C'est un inhibiteur de l'α-galactosidase A potentiellement capable de jouer un rôle de chaperon pharmacologique en restaurant la structure tridimensionnelle et l'activité enzymatique d'une α-galactosidase A mutante [5,6].…”

“…C'est un inhibiteur de l'α-galactosidase A potentiellement capable de jouer un rôle de chaperon pharmacologique en restaurant la structure tridimensionnelle et l'activité enzymatique d'une α-galactosidase A mutante [5,6]. Des travaux de recherche fondamentaux [8,9], précliniques [6], puis cliniques ont conduit à son utilisation en clinique humaine [7]. Les …”