2b4f
From Proteopedia
(New page: 200px<br /><applet load="2b4f" size="350" color="white" frame="true" align="right" spinBox="true" caption="2b4f, resolution 1.95Å" /> '''Structure Of A Cold-...) |
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==Overview== | ==Overview== | ||
| - | The structures of inactive mutants D144A and E78Q of the glycoside | + | The structures of inactive mutants D144A and E78Q of the glycoside hydrolase family 8 (GH-8) endo-beta-1,4-d-xylanase (pXyl) from the Antarctic bacterium Pseudoalteromonas haloplanktis TAH3a in complex with its substrate xylopentaose (at 1.95 A resolution) and product xylotriose (at 1.9 A resolution) have been determined by X-ray crystallography. A detailed comparative analysis of these with the apo-enzyme and with other GH-8 structures indicates an induced fit mechanism upon ligand binding whereby a number of conformational changes and, in particular, a repositioning of the proton donor into a more catalytically competent position occurs. This has also allowed for the description of protein-ligand interactions in this enzyme and for the demarcation of subsites -3 to +3. An in-depth analysis of each of these subsites gives an insight into the structure-function relationship of this enzyme and the basis of xylose/glucose discrimination in family 8 glycoside hydrolases. Furthermore, the structure of the -1/+1 subsite spanning complex reveals that the substrate is distorted from its ground state conformation. Indeed, structural analysis and in silico docking studies indicate that substrate hydrolysis in GH-8 members is preceded by a conformational change, away from the substrate ground-state chair conformation, to a pretransition state local minimum (2)S(O) conformation. |
==About this Structure== | ==About this Structure== | ||
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[[Category: Pseudoalteromonas haloplanktis]] | [[Category: Pseudoalteromonas haloplanktis]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Beeumen, J | + | [[Category: Beeumen, J J.Van.]] |
[[Category: Collins, T.]] | [[Category: Collins, T.]] | ||
[[Category: Feller, G.]] | [[Category: Feller, G.]] | ||
| - | [[Category: Savvides, S | + | [[Category: Savvides, S N.]] |
| - | [[Category: Vos, D | + | [[Category: Vos, D De.]] |
[[Category: cold adaptation]] | [[Category: cold adaptation]] | ||
[[Category: family 8]] | [[Category: family 8]] | ||
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[[Category: xylan degradation]] | [[Category: xylan degradation]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:34:02 2008'' |
Revision as of 14:34, 21 February 2008
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Structure Of A Cold-Adapted Family 8 Xylanase in complex with substrate
Overview
The structures of inactive mutants D144A and E78Q of the glycoside hydrolase family 8 (GH-8) endo-beta-1,4-d-xylanase (pXyl) from the Antarctic bacterium Pseudoalteromonas haloplanktis TAH3a in complex with its substrate xylopentaose (at 1.95 A resolution) and product xylotriose (at 1.9 A resolution) have been determined by X-ray crystallography. A detailed comparative analysis of these with the apo-enzyme and with other GH-8 structures indicates an induced fit mechanism upon ligand binding whereby a number of conformational changes and, in particular, a repositioning of the proton donor into a more catalytically competent position occurs. This has also allowed for the description of protein-ligand interactions in this enzyme and for the demarcation of subsites -3 to +3. An in-depth analysis of each of these subsites gives an insight into the structure-function relationship of this enzyme and the basis of xylose/glucose discrimination in family 8 glycoside hydrolases. Furthermore, the structure of the -1/+1 subsite spanning complex reveals that the substrate is distorted from its ground state conformation. Indeed, structural analysis and in silico docking studies indicate that substrate hydrolysis in GH-8 members is preceded by a conformational change, away from the substrate ground-state chair conformation, to a pretransition state local minimum (2)S(O) conformation.
About this Structure
2B4F is a Single protein structure of sequence from Pseudoalteromonas haloplanktis. Active as Endo-1,4-beta-xylanase, with EC number 3.2.1.8 Full crystallographic information is available from OCA.
Reference
Oligosaccharide binding in family 8 glycosidases: crystal structures of active-site mutants of the beta-1,4-xylanase pXyl from Pseudoaltermonas haloplanktis TAH3a in complex with substrate and product., De Vos D, Collins T, Nerinckx W, Savvides SN, Claeyssens M, Gerday C, Feller G, Van Beeumen J, Biochemistry. 2006 Apr 18;45(15):4797-807. PMID:16605248
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