3A0F

The crystal structure of Geotrichum sp. M128 xyloglucanase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.276 
  • R-Value Work: 0.236 
  • R-Value Observed: 0.238 

wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

The crystal structure of a xyloglucan-specific endo-beta-1,4-glucanase from Geotrichum sp. M128 xyloglucanase reveals a key amino acid residue for substrate specificity

Yaoi, K.Kondo, H.Hiyoshi, A.Noro, N.Sugimoto, H.Tsuda, S.Miyazaki, K.

(2009) FEBS J 276: 5094-5100

  • DOI: 10.1111/j.1742-4658.2009.07205.x
  • Primary Citation of Related Structures:  
    3A0F

  • PubMed Abstract: 
  • Geotrichum sp. M128 possesses two xyloglucan-specific glycoside hydrolases belonging to family 74, xyloglucan-specific endo-beta-1,4-glucanase (XEG) and oligoxyloglucan reducing-end-specific cellobiohydrolase (OXG-RCBH). Despite their similar amino acid sequences (48% identity), their modes of action and substrate specificities are distinct ...

    Geotrichum sp. M128 possesses two xyloglucan-specific glycoside hydrolases belonging to family 74, xyloglucan-specific endo-beta-1,4-glucanase (XEG) and oligoxyloglucan reducing-end-specific cellobiohydrolase (OXG-RCBH). Despite their similar amino acid sequences (48% identity), their modes of action and substrate specificities are distinct. XEG catalyzes the hydrolysis of xyloglucan polysaccharides in endo mode, while OXG-RCBH acts on xyloglucan oligosaccharides at the reducing end in exo mode. Here, we determined the crystal structure of XEG at 2.5 A resolution, and compared it to a previously determined structure of OXG-RCBH. For the most part, the amino acid residues that interact with substrate are conserved between the two enzymes. However, there are notable differences at subsite positions -1 and +2. OXG-RCBH has a loop around the +2 site that blocks one end of the active site cleft, which accounts for its exo mode of action. In contrast, XEG lacks a corresponding loop at this site, thereby allowing binding to the middle of the main chain of the substrate. At the -1 site in OXG-RCBH, Asn488 interacts with the xylose side chain of the substrate, whereas the -1 site is occupied by Tyr457 in XEG. To confirm the contribution of this residue to substrate specificity, Tyr457 was substituted by Gly in XEG. The wild-type XEG cleaved the oligoxyloglucan at a specific site; the Y457G variant cleaved the same substrate, but at various sites. Together, the absence of a loop in the cleft and the presence of bulky Tyr457 determine the substrate specificity of XEG.


    Organizational Affiliation

    Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan. k-yaoi@aist.go.jp



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
XyloglucanaseA763Geotrichum sp. M128Mutation(s): 0 
Gene Names: XEG
EC: 3.2.1.151
UniProt
Find proteins for Q764N8 (Geotrichum sp. (strain M128))
Explore Q764N8 
Go to UniProtKB:  Q764N8
Protein Feature View
Expand
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.276 
  • R-Value Work: 0.236 
  • R-Value Observed: 0.238 
  • Space Group: P 32 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 135.192α = 90
b = 135.192β = 90
c = 119.895γ = 120
Software Package:
Software NamePurpose
REFMACrefinement
HKL-2000data collection
HKL-2000data reduction
HKL-2000data scaling
AMoREphasing

Structure Validation

View Full Validation Report




Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2009-09-08
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance