2ahf
From Proteopedia
(New page: 200px<br /><applet load="2ahf" size="450" color="white" frame="true" align="right" spinBox="true" caption="2ahf, resolution 1.52Å" /> '''Unsaturated glucuron...) |
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| - | [[Image:2ahf.gif|left|200px]]<br /><applet load="2ahf" size=" | + | [[Image:2ahf.gif|left|200px]]<br /><applet load="2ahf" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="2ahf, resolution 1.52Å" /> | caption="2ahf, resolution 1.52Å" /> | ||
'''Unsaturated glucuronyl hydrolase mutant D88N'''<br /> | '''Unsaturated glucuronyl hydrolase mutant D88N'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Unsaturated glucuronyl hydrolase (UGL), which is a member of glycoside | + | Unsaturated glucuronyl hydrolase (UGL), which is a member of glycoside hydrolase family GH-88, is a bacterial enzyme that degrades mammalian glycosaminoglycans and bacterial biofilms. The enzyme, which acts on unsaturated oligosaccharides with an alpha-glycoside bond produced by microbial polysaccharide lyases responsible for bacterial invasion of host cells, was believed to release 4-deoxy-l-threo-5-hexosulose-uronate (unsaturated glucuronic acid, or DeltaGlcA) and saccharide with a new nonreducing terminus by hydrolyzing the glycosidic bond. We detail the crystal structures of wild-type inactive mutant UGL of Bacillus sp. GL1 and its complex with a substrate (unsaturated chondroitin disaccharide), identify active site residues, and postulate a reaction mechanism catalyzed by UGL that triggers the hydration of the vinyl ether group in DeltaGlcA, based on the structural analysis of the enzyme-substrate complex and biochemical analysis. The proposed catalytic mechanism of UGL is a novel case among known glycosidases. Under the proposed mechanism, Asp-149 acts as a general acid and base catalyst to protonate the DeltaGlcA C4 atom and to deprotonate the water molecule. The deprotonated water molecule attacks the DeltaGlcA C5 atom to yield unstable hemiketal; this is followed by spontaneous conversion to an aldehyde (4-deoxy-l-threo-5-hexosulose-uronate) and saccharide through hemiacetal formation and cleavage of the glycosidic bond. UGL is the first clarified alpha(6)/alpha(6)-barrel enzyme using aspartic acid as the general acid/base catalyst. |
==About this Structure== | ==About this Structure== | ||
| - | 2AHF is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_sp. Bacillus sp.]. Full crystallographic information is available from [http:// | + | 2AHF is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_sp. Bacillus sp.]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2AHF OCA]. |
==Reference== | ==Reference== | ||
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[[Category: glycoside hydrolase family 88]] | [[Category: glycoside hydrolase family 88]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:27:27 2008'' |
Revision as of 14:27, 21 February 2008
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Unsaturated glucuronyl hydrolase mutant D88N
Overview
Unsaturated glucuronyl hydrolase (UGL), which is a member of glycoside hydrolase family GH-88, is a bacterial enzyme that degrades mammalian glycosaminoglycans and bacterial biofilms. The enzyme, which acts on unsaturated oligosaccharides with an alpha-glycoside bond produced by microbial polysaccharide lyases responsible for bacterial invasion of host cells, was believed to release 4-deoxy-l-threo-5-hexosulose-uronate (unsaturated glucuronic acid, or DeltaGlcA) and saccharide with a new nonreducing terminus by hydrolyzing the glycosidic bond. We detail the crystal structures of wild-type inactive mutant UGL of Bacillus sp. GL1 and its complex with a substrate (unsaturated chondroitin disaccharide), identify active site residues, and postulate a reaction mechanism catalyzed by UGL that triggers the hydration of the vinyl ether group in DeltaGlcA, based on the structural analysis of the enzyme-substrate complex and biochemical analysis. The proposed catalytic mechanism of UGL is a novel case among known glycosidases. Under the proposed mechanism, Asp-149 acts as a general acid and base catalyst to protonate the DeltaGlcA C4 atom and to deprotonate the water molecule. The deprotonated water molecule attacks the DeltaGlcA C5 atom to yield unstable hemiketal; this is followed by spontaneous conversion to an aldehyde (4-deoxy-l-threo-5-hexosulose-uronate) and saccharide through hemiacetal formation and cleavage of the glycosidic bond. UGL is the first clarified alpha(6)/alpha(6)-barrel enzyme using aspartic acid as the general acid/base catalyst.
About this Structure
2AHF is a Single protein structure of sequence from Bacillus sp.. Full crystallographic information is available from OCA.
Reference
Crystal structure of unsaturated glucuronyl hydrolase complexed with substrate: molecular insights into its catalytic reaction mechanism., Itoh T, Hashimoto W, Mikami B, Murata K, J Biol Chem. 2006 Oct 6;281(40):29807-16. Epub 2006 Aug 7. PMID:16893885
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