2bs9: Difference between revisions
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==Overview== | ==Overview== | ||
Beta-D-Xylosidases are glycoside hydrolases that catalyse the release of | Beta-D-Xylosidases are glycoside hydrolases that catalyse the release of xylose units from short xylooligosaccharides and are engaged in the final breakdown of plant cell-wall hemicelluloses. beta-D-Xylosidases are found in glycoside hydrolase families 3, 39, 43, 52 and 54. The first crystal structure of a GH39 beta-xylosidase revealed a multi-domain organization with the catalytic domain having the canonical (beta/alpha)8 barrel fold. Here, we report the crystal structure of the GH39 Geobacillus stearothermophilus beta-D-xylosidase, inactivated by a point mutation of the general acid-base residue E160A, in complex with the chromogenic substrate molecule 2,5-dinitrophenyl-beta-D-xyloside. Surprisingly, six of the eight active sites present in the crystallographic asymmetric unit contain the trapped covalent glycosyl-enzyme intermediate, while two of them still contain the uncleaved substrate. The structural characterization of these two critical species along the reaction coordinate of this enzyme identifies the residues forming its xyloside-binding pocket as well as those essential for its aglycone recognition. | ||
==About this Structure== | ==About this Structure== | ||
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[[Category: thermophilic enzyme]] | [[Category: thermophilic enzyme]] | ||
''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 16:41:09 2008'' | ||
Revision as of 17:41, 21 February 2008
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NATIVE CRYSTAL STRUCTURE OF A GH39 BETA-XYLOSIDASE XYNB1 FROM GEOBACILLUS STEAROTHERMOPHILUS
OverviewOverview
Beta-D-Xylosidases are glycoside hydrolases that catalyse the release of xylose units from short xylooligosaccharides and are engaged in the final breakdown of plant cell-wall hemicelluloses. beta-D-Xylosidases are found in glycoside hydrolase families 3, 39, 43, 52 and 54. The first crystal structure of a GH39 beta-xylosidase revealed a multi-domain organization with the catalytic domain having the canonical (beta/alpha)8 barrel fold. Here, we report the crystal structure of the GH39 Geobacillus stearothermophilus beta-D-xylosidase, inactivated by a point mutation of the general acid-base residue E160A, in complex with the chromogenic substrate molecule 2,5-dinitrophenyl-beta-D-xyloside. Surprisingly, six of the eight active sites present in the crystallographic asymmetric unit contain the trapped covalent glycosyl-enzyme intermediate, while two of them still contain the uncleaved substrate. The structural characterization of these two critical species along the reaction coordinate of this enzyme identifies the residues forming its xyloside-binding pocket as well as those essential for its aglycone recognition.
About this StructureAbout this Structure
2BS9 is a Single protein structure of sequence from Geobacillus stearothermophilus with as ligand. Active as Xylan 1,4-beta-xylosidase, with EC number 3.2.1.37 Known structural/functional Site: . Full crystallographic information is available from OCA.
ReferenceReference
Enzyme-substrate complex structures of a GH39 beta-xylosidase from Geobacillus stearothermophilus., Czjzek M, Ben David A, Bravman T, Shoham G, Henrissat B, Shoham Y, J Mol Biol. 2005 Nov 4;353(4):838-46. Epub 2005 Sep 20. PMID:16212978
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