2f61
From Proteopedia
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Crystal structure of partially deglycosylated acid beta-glucosidase
Contents |
Overview
Acid beta-glucosidase (GCase) is a 497-amino acid, membrane-associated, lysosomal exo-beta-glucosidase whose defective activity leads to the, Gaucher disease phenotypes. To move toward a structure/function map for, disease mutations, 52 selected single amino acid substitutions were, introduced into GCase, expressed in an insect cell system, purified, and, characterized for basic kinetic, stability, and activator response, properties. The variant GCases from Gaucher disease patients and selected, variant GCases from the mouse had decreased relative k(cat) and, differential effects on active site binding and/or attachment of, mechanism-based covalent (conduritol B epoxide) or reversible, (deoxynojirimycin derivatives) inhibitors. A defect in negatively charged, phospholipid activation was present in the majority of variant GCases but, was increased in two, N370S and V394L. Deficits in saposin C enhancement, of k(cat) were present in variant GCases involving residues 48-122, whereas approximately 2-fold increases were obtained with the L264I GCase., About 50% of variant GCases each had wild-type or increased sensitivity to, in vitro cathepsin D digestion. Mapping of these properties onto the, crystal structures of GCase indicated wide dispersion of functional, properties that can affect catalytic function and stability. Site-directed, mutagenesis of cysteine residues showed that the disulfide bonds, Cys(4)-Cys(16) and Cys(18)-Cys(23), and a free Cys(342) were essential for, activity; the free Cys(126) and Cys(248) were not. Relative k(cat) was, highly sensitive to a His substitution at Arg(496) but not at Arg(495)., These studies and high phylogenetic conservation indicate localized and, general structural effects of Gaucher disease mutations that were not, obvious from the nature of the amino acid substitution, including those, predicted to be nondisruptive (e.g. Val --> Leu). These results provide, initial studies for the engineering of variant GCases and, potentially, molecular chaperones for therapeutic use.
Disease
Known diseases associated with this structure: Gaucher disease, perinatal lethal OMIM:[606463], Gaucher disease, type I OMIM:[606463], Gaucher disease, type II OMIM:[606463], Gaucher disease, type III OMIM:[606463], Gaucher disease, type IIIC OMIM:[606463]
About this Structure
2F61 is a Single protein structure of sequence from Homo sapiens with NDG and SO4 as ligands. Active as Glucosylceramidase, with EC number 3.2.1.45 Full crystallographic information is available from OCA.
Reference
Analyses of variant acid beta-glucosidases: effects of Gaucher disease mutations., Liou B, Kazimierczuk A, Zhang M, Scott CR, Hegde RS, Grabowski GA, J Biol Chem. 2006 Feb 17;281(7):4242-53. Epub 2005 Nov 17. PMID:16293621
Page seeded by OCA on Mon Nov 12 22:00:06 2007
