PDBsum entry 2c7f

Hydrolase

PDB id: 2c7f

Contents

Protein chains

(+ 0 more) 496 a.a. *

Ligands

AHR-AHR-AHR ×4

AHR-AHR ×2

EDO ×9

Waters ×117

* Residue conservation analysis

PDB id:

2c7f

Name:

Hydrolase

Title:

The structure of a family 51 arabinofuranosidase, araf51, from clostridium thermocellum in complex with 1,5-alpha-l-arabinotriose.

Structure:

Alpha-l-arabinofuranosidase. Chain: a, b, c, d, e, f. Synonym: arabinofuranosidase. Engineered: yes. Mutation: yes

Source:

Clostridium thermocellum. Organism_taxid: 1515. Strain: f1 / ys. Atcc: 27405. Expressed in: escherichia coli. Expression_system_taxid: 469008.

Resolution:

2.70Å R-factor: 0.243 R-free: 0.255

Authors:

E.J.Taylor,N.L.Smith,J.P.Turkenburg,S.D'Souza,H.J.Gilbert,G.J.Davies

Key ref:

E.J.Taylor et al. (2006). Structural insight into the ligand specificity of a thermostable family 51 arabinofuranosidase, Araf51, from Clostridium thermocellum. Biochem J, 395, 31-37. PubMed id: 16336192

Date:

23-Nov-05 Release date: 14-Dec-05

Protein chains

A3DIH0  (IABF_CLOTH) -  Intracellular exo-alpha-(1->5)-L-arabinofuranosidase from Acetivibrio thermocellus (strain ATCC 27405 / DSM 1237 / JCM 9322 / NBRC 103400 / NCIMB 10682 / NRRL B-4536 / VPI 7372)

Seq: 503 a.a.

Struc: 496 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.3.2.1.55 - non-reducing end alpha-L-arabinofuranosidase.
• Reaction: Hydrolysis of terminal non-reducing alpha-L-arabinofuranoside residues in alpha-L-arabinosides.

Biochem J 395:31-37 (2006)

PubMed id: 16336192

Structural insight into the ligand specificity of a thermostable family 51 arabinofuranosidase, Araf51, from Clostridium thermocellum.

E.J.Taylor, N.L.Smith, J.P.Turkenburg, S.D'Souza, H.J.Gilbert, G.J.Davies.

ABSTRACT

The digestion of the plant cell wall requires the concerted action of a diverse repertoire of enzyme activities. An important component of these hydrolase consortia are arabinofuranosidases, which release L-arabinofuranose moieties from a range of plant structural polysaccharides. The anaerobic bacterium Clostridium thermocellum, a highly efficient plant cell wall degrader, possesses a single alpha-L-arabinofuranosidase (EC 3.2.1.55), CtAraf51A, located in GH51 (glycoside hydrolase family 51). The crystal structure of the enzyme has been solved in native form and in 'Michaelis' complexes with both alpha-1,5-linked arabinotriose and alpha-1,3 arabinoxylobiose, both forming a hexamer in the asymmetric unit. Kinetic studies reveal that CtAraf51A, in contrast with well-characterized GH51 enzymes including the Cellvibrio japonicus enzyme [Beylot, McKie, Voragen, Doeswijk-Voragen and Gilbert (2001) Biochem. J. 358, 607-614], catalyses the hydrolysis of alpha-1,5-linked arabino-oligosaccharides and the alpha-1,3 arabinosyl side chain decorations of xylan with equal efficiency. The paucity of direct hydrogen bonds with the aglycone moiety and the flexible conformation adopted by Trp(178), which stacks against the sugar at the +1 subsite, provide a structural explanation for the plasticity in substrate specificity displayed by the clostridial arabinofuranosidase.