3C7G: Crystal Structure Of A Glycoside Hydrolase Family 43 Arabinoxylan Arabinofuranohydrolase From Bacillus Subtilis In Complex With Xylotetraose

AXHs (arabinoxylan arabinofuranohydrolases) are alpha-L-arabinofuranosidases that specifically hydrolyse the glycosidic bond between arabinofuranosyl substituents and xylopyranosyl backbone residues of arabinoxylan. Bacillus subtilis was recently shown to produce an AXH that cleaves arabinose units from O-2- or O-3-mono-substituted xylose residues: BsAXH-m2,3 (B. subtilis AXH-m2,3). Crystallographic analysis reveals a two-domain structure for this enzyme: a catalytic domain displaying a five-bladed beta-propeller fold characteristic of GH (glycoside hydrolase) family 43 and a CBM (carbohydrate-binding module) with a beta-sandwich fold belonging to CBM family 6. Binding of substrate to BsAXH-m2,3 is largely based on hydrophobic stacking interactions, which probably allow the positional flexibility needed to hydrolyse both arabinose substituents at the O-2 or O-3 position of the xylose unit. Superposition of the BsAXH-m2,3 structure with known structures of the GH family 43 exo-acting enzymes, beta-xylosidase and alpha-L-arabinanase, each in complex with their substrate, reveals a different orientation of the sugar backbone.
PDB ID: 3C7GDownload
MMDB ID: 67991
PDB Deposition Date: 2008/2/7
Updated in MMDB: 2008/11
Experimental Method:
x-ray diffraction
Resolution: 2.02  Å
Source Organism:
Similar Structures:
Biological Unit for 3C7G: monomeric; determined by author and by software (PISA)
Molecular Components in 3C7G
Label Count Molecule
Protein (1 molecule)
Endo-1,4-beta-xylanase(Gene symbol: xynD)
Molecule annotation
Chemicals (8 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB