Biochemical and structural study on a S529V mutant acid α-glucosidase responsive to pharmacological chaperones

• Published in: Journal of human genetics Vol. 56; no. 6; pp. 440 - 446
• Main Authors: Tajima, Youichi, Saito, Seiji, Ohno, Kazuki, Tsukimura, Takahiro, Tsujino, Seiichi, Sakuraba, Hitoshi
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 01.06.2011
• Subjects: alpha-Glucosidases - chemistry; alpha-Glucosidases - genetics; alpha-Glucosidases - metabolism; Amino Acid Substitution - genetics; Amino acids; Animals; Catalytic Domain - genetics; Cell lines; Cells, Cultured; Chaperones; CHO Cells; Cricetinae; Cricetulus; Enzymatic activity; Enzyme Activation - drug effects; Fibroblasts - drug effects; Gene Expression Regulation - drug effects; Glycogen Storage Disease Type II - enzymology; Glycogen Storage Disease Type II - genetics; Humans; Hydrogen bonding; Imino Sugars - metabolism; Imino Sugars - pharmacology; Models, Molecular; Mutant Proteins - chemistry; Mutant Proteins - metabolism; Mutants; Protein Binding; Protein Conformation; Sulfonic acid; Western blotting; α-Glucosidase
• ISSN: 1434-5161; 1435-232X
• DOI: 10.1038/jhg.2011.36

Recently, pharmacological chaperone therapy for Pompe disease with small molecules such as imino sugars has attracted interest. But mutant acid α-glucosidase (GAA) species responsive to imino sugars are limited. To elucidate the characteristics of a mutant GAA responsive to imino sugars, we performed biochemical and structural analyses. Among cultured fibroblast cell lines derived from Japanese Pompe patients, only one carrying p.S529V/p.S619R amino acid substitutions responded to 1-deoxynojirimycin (DNJ), and an expression study revealed that DNJ, N-butyl-deoxynojirimycin and nojirimycin-1-sulfonic acid increased the enzyme activity of the S529V mutant GAA expressed in Chinese hamster ovary cells. The results of western blotting analysis suggested that these imino sugars facilitated the intracellular transportation of the mutant GAA and stabilized it. Among these imino sugars, DNJ exhibited the strongest action on the mutant GAA. Structural analysis revealed that DNJ almost completely occupied the active site pocket, and interacted with amino acid residues comprising it through van der Waals contacts and hydrogen bonds. This information will be useful for improvement of pharmacological chaperone therapy for Pompe disease.