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| {{STRUCTURE_2d22| PDB=2d22 | SCENE= }} | | {{STRUCTURE_2d22| PDB=2d22 | SCENE= }} |
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| '''Crystal structure of covalent glycosyl-enzyme intermediate of catalytic-site mutant xylanase from Streptomyces olivaceoviridis E-86'''
| | ===Crystal structure of covalent glycosyl-enzyme intermediate of catalytic-site mutant xylanase from Streptomyces olivaceoviridis E-86=== |
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| ==Overview==
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| Xylanases hydrolyse the beta-1,4-glycosidic bonds within the xylan backbone and belong to either family 10 or 11 of the glycoside hydrolases, on the basis of the amino acid sequence similarities of their catalytic domains. Generally, xylanases have a core catalytic domain, an N and/or C-terminal substrate-binding domain and a linker region. Until now, X-ray structural analyses of family 10 xylanases have been reported only for their catalytic domains and do not contain substrate-binding domains. We have determined the crystal structure of a family 10 xylanase containing the xylan-binding domain (XBD) from Streptomyces olivaceoviridis E-86 at 1.9 A resolution. The catalytic domain comprises a (beta/alpha)(8)-barrel topologically identical to other family 10 xylanases. XBD has three similar subdomains, as suggested from a triple-repeat sequence, which are assembled against one another around a pseudo-3-fold axis, forming a galactose-binding lectin fold similar to ricin B-chain. The Gly/Pro-rich linker region connecting the catalytic domain and XBD is not visible in the electron density map, probably because of its flexibility. The interface of the two domains in the crystal is hydrophilic, where five direct hydrogen bonds and water-mediated hydrogen bonds exist. The sugar-binding residues seen in ricin/lactose complex are spatially conserved among the three subdomains in XBD, suggesting that all of the subdomains in XBD have the capacity to bind sugars. The flexible linker region enables the two domains to move independently and may provide a triple chance of substrate capturing and catalysis. The structure reported here represents an example where the metabolic enzyme uses a ricin-type lectin motif for capturing the insoluble substrate and promoting catalysis.
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| ==About this Structure== | | ==About this Structure== |
| 2D22 is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Streptomyces_olivaceoviridis Streptomyces olivaceoviridis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2D22 OCA]. | | 2D22 is a 2 chains structure of sequences from [http://en.wikipedia.org/wiki/Streptomyces_olivaceoviridis Streptomyces olivaceoviridis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2D22 OCA]. |
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| ==Reference== | | ==Reference== |
| Crystal structure of Streptomyces olivaceoviridis E-86 beta-xylanase containing xylan-binding domain., Fujimoto Z, Kuno A, Kaneko S, Yoshida S, Kobayashi H, Kusakabe I, Mizuno H, J Mol Biol. 2000 Jul 14;300(3):575-85. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/10884353 10884353]
| | <ref group="xtra">PMID:10884353</ref><ref group="xtra">PMID:11829503</ref><ref group="xtra">PMID:14670957</ref><ref group="xtra">PMID:10359093</ref><references group="xtra"/> |
| [[Category: Endo-1,4-beta-xylanase]] | | [[Category: Endo-1,4-beta-xylanase]] |
| [[Category: Single protein]]
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| [[Category: Streptomyces olivaceoviridis]] | | [[Category: Streptomyces olivaceoviridis]] |
| [[Category: Fujimoto, Z.]] | | [[Category: Fujimoto, Z.]] |
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| [[Category: Retaining enzyme]] | | [[Category: Retaining enzyme]] |
| [[Category: Tim-barrel]] | | [[Category: Tim-barrel]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 23:33:17 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Feb 17 21:48:08 2009'' |
