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'''Unsaturated glucuronyl hydrolase mutant D88N''' | '''Unsaturated glucuronyl hydrolase mutant D88N''' | ||
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[[Category: Mikami, B.]] | [[Category: Mikami, B.]] | ||
[[Category: Murata, K.]] | [[Category: Murata, K.]] | ||
[[Category: | [[Category: Alpha6/alpha6 barrel]] | ||
[[Category: | [[Category: Glycoside hydrolase family 88]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 19:03:11 2008'' | |||
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Revision as of 16:03, 3 May 2008
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 Page seeded by OCA on Sat May 3 19:03:11 2008
