title: Human α-L-iduronidase uses its own N-glycan as a substrate-binding and catalytic module.
abstract: N-glycosylation is a major posttranslational modification that endows proteins with various functions. It is established that N-glycans are essential for the correct folding and stability of some enzymes; however, the actual effects of N-glycans on their activities are poorly understood. Here, we show that human α-l-iduronidase (hIDUA), of which a dysfunction causes accumulation of dermatan/heparan sulfate leading to mucopolysaccharidosis type I, uses its own N-glycan as a substrate binding and catalytic module. Structural analysis revealed that the mannose residue of the N-glycan attached to N372 constituted a part of the substrate-binding pocket and interacted directly with a substrate. A deglycosylation study showed that enzyme activity was highly correlated with the N-glycan attached to N372. The kinetics of native and deglycosylated hIDUA suggested that the N-glycan is also involved in catalytic processes. Our study demonstrates a previously unrecognized function of N-glycans.
authors: Laboratory of X-Ray Crystallography, Institute for Enzyme Research, University of Tokushima, Tokushima 770-8503, Japan. nmaita@tokushima-u.ac.jp
authors: Nobuo
authors: N
authors: Maita
authors: Takahiro
authors: T
authors: Tsukimura
authors: Takako
authors: T
authors: Taniguchi
authors: Seiji
authors: S
authors: Saito
authors: Kazuki
authors: K
authors: Ohno
authors: Hisaaki
authors: H
authors: Taniguchi
authors: Hitoshi
authors: H
authors: Sakuraba
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D055162:Biocatalysis; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D003871:Dermatan Sulfate / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006497:Heparan Sulfate / Q000378:metabolism; D006801:Humans; D007068:Iduronidase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008358:Mannose / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008059:Mucopolysaccharidosis I / Q000201:enzymology / Q000378:metabolism; D009154:Mutation; D011134:Polysaccharides / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D003871:Dermatan Sulfate; D006497:Heparan Sulfate; D007068:Iduronidase; D008358:Mannose; D011134:Polysaccharides
keywords: N-linked glycan; X-ray crystallography; glycoside hydrolase family 39
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