2xbd
From Proteopedia
| Line 4: | Line 4: | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: Many enzymes that digest polysaccharides contain separate | + | BACKGROUND: Many enzymes that digest polysaccharides contain separate polysaccharide-binding domains. Structures have been previously determined for a number of cellulose-binding domains (CBDs) from cellulases. RESULTS: The family IIb xylan-binding domain 1 (XBD1) from Cellulomonas fimi xylanase D is shown to bind xylan but not cellulose. Its structure is similar to that of the homologous family IIa CBD from C. fimi Cex, consisting of two four-stranded beta sheets that form a twisted 'beta sandwich'. The xylan-binding site is a groove made from two tryptophan residues that stack against the faces of the sugar rings, plus several hydrogen-bonding polar residues. CONCLUSIONS: The biggest difference between the family IIa and IIb domains is that in the former the solvent-exposed tryptophan sidechains are coplanar, whereas in the latter they are perpendicular, forming a twisted binding site. The binding sites are therefore complementary to the secondary structures of the ligands cellulose and xylan. XBD1 and CexCBD represent a striking example of two proteins that have high sequence similarity but a different function. |
==About this Structure== | ==About this Structure== | ||
| Line 14: | Line 14: | ||
[[Category: Endo-1,4-beta-xylanase]] | [[Category: Endo-1,4-beta-xylanase]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Bolam, D | + | [[Category: Bolam, D N.]] |
[[Category: Ciruela, A.]] | [[Category: Ciruela, A.]] | ||
[[Category: Cooper, A.]] | [[Category: Cooper, A.]] | ||
| - | [[Category: Gilbert, H | + | [[Category: Gilbert, H J.]] |
| - | [[Category: Hazlewood, G | + | [[Category: Hazlewood, G P.]] |
| - | [[Category: Simpson, P | + | [[Category: Simpson, P J.]] |
| - | [[Category: Williamson, M | + | [[Category: Williamson, M P.]] |
[[Category: beta-sheet]] | [[Category: beta-sheet]] | ||
[[Category: hydrolase]] | [[Category: hydrolase]] | ||
| Line 26: | Line 26: | ||
[[Category: xylanase]] | [[Category: xylanase]] | ||
| - | ''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 18:56:57 2008'' |
Revision as of 16:56, 21 February 2008
|
INTERNAL XYLAN BINDING DOMAIN FROM CELLULOMONAS FIMI XYLANASE D, NMR, MINIMIZED AVERAGE STRUCTURE
Overview
BACKGROUND: Many enzymes that digest polysaccharides contain separate polysaccharide-binding domains. Structures have been previously determined for a number of cellulose-binding domains (CBDs) from cellulases. RESULTS: The family IIb xylan-binding domain 1 (XBD1) from Cellulomonas fimi xylanase D is shown to bind xylan but not cellulose. Its structure is similar to that of the homologous family IIa CBD from C. fimi Cex, consisting of two four-stranded beta sheets that form a twisted 'beta sandwich'. The xylan-binding site is a groove made from two tryptophan residues that stack against the faces of the sugar rings, plus several hydrogen-bonding polar residues. CONCLUSIONS: The biggest difference between the family IIa and IIb domains is that in the former the solvent-exposed tryptophan sidechains are coplanar, whereas in the latter they are perpendicular, forming a twisted binding site. The binding sites are therefore complementary to the secondary structures of the ligands cellulose and xylan. XBD1 and CexCBD represent a striking example of two proteins that have high sequence similarity but a different function.
About this Structure
2XBD is a Single protein structure of sequence from Cellulomonas fimi. Active as Endo-1,4-beta-xylanase, with EC number 3.2.1.8 Known structural/functional Site: . Full crystallographic information is available from OCA.
Reference
A family IIb xylan-binding domain has a similar secondary structure to a homologous family IIa cellulose-binding domain but different ligand specificity., Simpson PJ, Bolam DN, Cooper A, Ciruela A, Hazlewood GP, Gilbert HJ, Williamson MP, Structure. 1999 Jul 15;7(7):853-64. PMID:10425686
Page seeded by OCA on Thu Feb 21 18:56:57 2008
