 |
PDBsum entry 3a0f
|
|
|
|
|
 |
Contents |
 |
|
|
|
|
|
|
|
|
|
|
* Residue conservation analysis
|
|
|
|
|
|
PDB id:
|
|
|
|
| Name: |
|
Hydrolase
|
|
|
Title:
|
|
The crystal structure of geotrichum sp. M128 xyloglucanase
|
|
Structure:
|
|
Xyloglucanase. Chain: a. Fragment: residues in unp 21-776. Synonym: xyloglucan-specific endo-beta-1,4-glucanase. Engineered: yes
|
|
Source:
|
|
Geotrichum sp. M128. Organism_taxid: 203496. Gene: xeg. Expressed in: escherichia coli. Expression_system_taxid: 562.
|
|
Resolution:
|
|
|
2.50Å
|
R-factor:
|
0.238
|
R-free:
|
0.276
|
|
|
Authors:
|
|
K.Yaoi,H.Kondo,A.Hiyoshi,N.Noro,H.Sugimoto,S.Tsuda,K.Miyazaki
|
|
Key ref:
|
|
K.Yaoi
et al.
(2009).
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.
Febs J,
276,
5094-5100.
PubMed id:
|
|
|
Date:
|
|
|
16-Mar-09
|
Release date:
|
08-Sep-09
|
|
|
|
|
|
|
PROCHECK
|
|
|
|
|
|
Headers
|
|
|
|
References
|
|
|
|
|
|
|
|
Q764N8
(Q764N8_GEOS1) -
Xyloglucanase from Geotrichum sp. (strain M128)
|
|
|
|
Seq:
Struc:
|
|
|
|
776 a.a.
753 a.a.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Key: |
 |
PfamA domain |
|
|
 |
Secondary structure |
|
 |
CATH domain |
|
|
|
|
|
|
|
|
|
|
|
|
|
Enzyme class:
|
|
E.C.3.2.1.151
- xyloglucan-specific endo-beta-1,4-glucanase.
|
|
|
|
|
|
|
Reaction:
|
|
xyloglucan + H2O = xyloglucan oligosaccharides
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
|
|
|
|
|
|
| |
|
|
Febs J
276:5094-5100
(2009)
|
|
PubMed id:
|
|
|
|
|
|
| |
|
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.
|
|
K.Yaoi,
H.Kondo,
A.Hiyoshi,
N.Noro,
H.Sugimoto,
S.Tsuda,
K.Miyazaki.
|
|
|
|
|
| |
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. 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.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
 |
 |
|
Links
