2f61: Difference between revisions
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[[Image:2f61.gif|left|200px]]<br /> | [[Image:2f61.gif|left|200px]]<br /><applet load="2f61" size="350" color="white" frame="true" align="right" spinBox="true" | ||
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caption="2f61, resolution 2.500Å" /> | caption="2f61, resolution 2.500Å" /> | ||
'''Crystal structure of partially deglycosylated acid beta-glucosidase'''<br /> | '''Crystal structure of partially deglycosylated acid beta-glucosidase'''<br /> | ||
==Overview== | ==Overview== | ||
Acid beta-glucosidase (GCase) is a 497-amino acid, membrane-associated | 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== | ==Disease== | ||
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==About this Structure== | ==About this Structure== | ||
2F61 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with NDG and SO4 as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Glucosylceramidase Glucosylceramidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.45 3.2.1.45] Full crystallographic information is available from [http:// | 2F61 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=NDG:'>NDG</scene> and <scene name='pdbligand=SO4:'>SO4</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Glucosylceramidase Glucosylceramidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.45 3.2.1.45] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2F61 OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Grabowski, G.]] | [[Category: Grabowski, G.]] | ||
[[Category: Hegde, R | [[Category: Hegde, R S.]] | ||
[[Category: NDG]] | [[Category: NDG]] | ||
[[Category: SO4]] | [[Category: SO4]] | ||
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[[Category: tim barrel]] | [[Category: tim barrel]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:18:06 2008'' | ||
Revision as of 18:18, 21 February 2008
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Crystal structure of partially deglycosylated acid beta-glucosidase
OverviewOverview
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.
DiseaseDisease
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 StructureAbout this Structure
2F61 is a Single protein structure of sequence from Homo sapiens with and as ligands. Active as Glucosylceramidase, with EC number 3.2.1.45 Full crystallographic information is available from OCA.
ReferenceReference
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
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