title: A carboxy-terminal truncation of human alpha-galactosidase A in a heterozygous female with Fabry disease and modification of the enzymatic activity by the carboxy-terminal domain. Increased, reduced, or absent enzyme activity depending on number of amino acid residues deleted.
abstract: Fabry disease is an X-linked disorder of glycosphingolipid metabolism caused by a deficiency of alpha-galactosidase A (alpha-Gal A). We identified a novel mutation of alpha-Gal A gene in a family with Fabry disease, which converted a tyrosine at codon 365 to a stop and resulted in a truncation of the carboxy (C) terminus by 65 amino acid (AA) residues. In a heterozygote of this family, although the mutant and normal alleles were equally transcribed in cultured fibroblasts, lymphocyte alpha-Gal A activity was approximately 30% of the normal control and severe clinical symptoms were apparent. COS-1 cells transfected with this mutant cDNA showed a complete loss of its enzymatic activity. Furthermore, those cotransfected with mutant and wildtype cDNAs showed a lower alpha-Gal A activity than those with wild type alone (approximately 30% of wild type alone), which suggested the dominant negative effect of this mutation and implied the importance of the C terminus for its activity. Thus, we generated mutant cDNAs with various deletion of the C terminus, and analyzed. Unexpectedly, alpha-Gal A activity was enhanced by up to sixfold compared with wild-type when from 2 to 10 AA residues were deleted. In contrast, deletion of 12 or more AA acid residues resulted in a complete loss of enzyme activity. Our data suggest that the C-terminal region of alpha-Gal A plays an important role in the regulation of its enzyme activity.
authors.affiliation: Department of Metabolic Medicine, Kumamoto University School of Medicine, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Miyamura
authors.forename: E
authors.initials: E
authors.lastname: Araki
authors.forename: K
authors.initials: K
authors.lastname: Matsuda
authors.forename: R
authors.initials: R
authors.lastname: Yoshimura
authors.forename: N
authors.initials: N
authors.lastname: Furukawa
authors.forename: K
authors.initials: K
authors.lastname: Tsuruzoe
authors.forename: T
authors.initials: T
authors.lastname: Shirotani
authors.forename: H
authors.initials: H
authors.lastname: Kishikawa
authors.forename: K
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: M
authors.initials: M
authors.lastname: Shichiri
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D000795:Fabry Disease / Q000235:genetics* / Q000628:therapy; D005260:Female; D006579:Heterozygote; D006801:Humans; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D010375:Pedigree; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000737:chemistry; D013329:Structure-Activity Relationship; D014960:X Chromosome; D000519:alpha-Galactosidase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D000519:alpha-Galactosidase