Unraveling the effect of A143T, P205T and D244N mutations in α-galactosidase A on its catalytic activity and susceptibility to globotriaosylceramide and iminosugar 1-deoxygalactonojirimycin chaperone

Abstract

Fabry disease (FD) is an X-linked lysosomal storage disorder caused by mutations in the GLA gene that encodes lysosomal α-galactosidase A (α-Gal A), an enzyme that catalyzes the hydrolysis of globotriaosylceramide (Gb3). Mutated α-Gal A causes protein misfolding, resulting in the decrease of its catalytic activity, stability, and transportation efficiency to the lysosome. Iminosugar 1-deoxygalactonojirimycin (DGJ) chaperone is reported to significantly recover the enzymatic activity of mutated α-Gal A, especially A143T, P205T, and D244N variants, to the normal level in Fabry patient cell lines. In the present study, the effect of A143T, P205T, and D244N mutations in α-Gal A on its catalytic activity and susceptibility to the Gb3 substrate and DGJ chaperone was theoretically investigated using molecular modeling approaches. The obtained results revealed that A143T, P205T, and D244N mutations decreased the catalytic activity of α-Gal A against Gb3 substrate by (i) increasing the structural fluctuation at the loop residues 54–62, (ii) decreasing the number of strong protein–ligand H-bonds, (iii) increasing the distances for nucleophilic attack and acid/base catalysis, and (iv) enlarging the solvent accessible surface area at the enzyme active site. Notably, the binding affinity against α-Gal A of DGJ was higher than that of the Gb3, indicating that DGJ is a good pharmacological chaperone (PC), supported by previously reported in vitro α-Gal A assay. The obtained structural information obtained from this study could pave the way for developing novel PCs targeting α-Gal A for the treatment of FD.