title: Molecular mechanism for stabilization of a mutant α-galactosidase A involving M51I amino acid substitution by imino sugars.
abstract: Small molecules including imino sugars are expected to act as chaperones for a mutant α-galactosidase A (GLA), which will be useful for pharmacological chaperone therapy for Fabry disease. However, there is little detailed information about the molecular mechanism. We paid attention to an M51I mutant GLA which had been reported to strongly react to an imino sugar. The predicted structural change caused by this amino acid substitution is very small and located on the surface of the molecule. We produced the mutant enzyme in yeast, and determined its enzymological characteristics. The enzymological parameter values are almost the same as those of the wild-type GLA, although the mutant enzyme is unstable not only under neutral pH conditions but also under acidic ones. Then, we directly examined the effect of imino sugars including 1-deoxygalactonojirimycin and galactostatin bisulfite on the purified mutant enzyme. The imino sugars apparently improved the stability of the mutant enzyme under both neutral and acidic pH conditions. The results of surface plasmon resonance biosensor assaying suggested that the imino sugars retained their binding activity as to the mutant enzyme under both neutral and acidic pH conditions. This information will facilitate improvement of pharmacological chaperone therapy for Fabry disease.
authors.affiliation: Department of Analytical Biochemistry, Meiji Pharmaceutical University, Kiyose, Tokyo, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Tsukimura
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Chiba
authors.forename: Kazuki
authors.initials: K
authors.lastname: Ohno
authors.forename: Seiji
authors.initials: S
authors.lastname: Saito
authors.forename: Youichi
authors.initials: Y
authors.lastname: Tajima
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sakuraba
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics*; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D004789:Enzyme Activation / Q000187:drug effects; D004795:Enzyme Stability / Q000187:drug effects / Q000235:genetics; D050111:Imino Sugars / Q000378:metabolism* / Q000494:pharmacology; D008958:Models, Molecular; D050505:Mutant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D000519:alpha-Galactosidase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D050111:Imino Sugars; D050505:Mutant Proteins; D000519:alpha-Galactosidase