spacer
spacer

PDBsum entry 3gzk

Go to PDB code: 
protein ligands metals links
Hydrolase PDB id
3gzk
Jmol
Contents
Protein chain
531 a.a. *
Ligands
MPD ×2
Metals
_CA
_ZN
Waters ×320
* Residue conservation analysis
PDB id:
3gzk
Name: Hydrolase
Title: Structure of a. Acidocaldarius cellulase cela
Structure: Cellulase. Chain: a. Engineered: yes
Source: Alicyclobacillus acidocaldarius subsp. Acidocaldarius. Bacillus acidocaldarius. Organism_taxid: 1388. Expressed in: escherichia coli. Expression_system_taxid: 562.
Resolution:
1.80Å     R-factor:   0.184     R-free:   0.213
Authors: S.Morera,K.Eckert,A.Vigouroux
Key ref:
K.Eckert et al. (2009). Crystal structures of A. acidocaldarius endoglucanase Cel9A in complex with Cello-oligosaccharides: strong -1 and -2 subsites mimic cellobiohydrolase activity. J Mol Biol, 394, 61-70. PubMed id: 19729024 DOI: 10.1016/j.jmb.2009.08.060
Date:
07-Apr-09     Release date:   13-Oct-09    
PROCHECK
Go to PROCHECK summary
 Headers
 References

Protein chain
Pfam   ArchSchema ?
Q9AJS0  (Q9AJS0_ALIAC) -  Cellulase
Seq:
Struc:
 
Seq:
Struc:
537 a.a.
531 a.a.
Key:    PfamA domain  Secondary structure  CATH domain

 Enzyme reactions 
   Enzyme class: E.C.3.2.1.4  - Cellulase.
[IntEnz]   [ExPASy]   [KEGG]   [BRENDA]
      Reaction: Endohydrolysis of 1,4-beta-D-glucosidic linkages in cellulose, lichenin and cereal beta-D-glucans.
 Gene Ontology (GO) functional annotation 
  GO annot!
  Biological process     metabolic process   2 terms 
  Biochemical function     catalytic activity     6 terms  

 

 
DOI no: 10.1016/j.jmb.2009.08.060 J Mol Biol 394:61-70 (2009)
PubMed id: 19729024  
 
 
Crystal structures of A. acidocaldarius endoglucanase Cel9A in complex with Cello-oligosaccharides: strong -1 and -2 subsites mimic cellobiohydrolase activity.
K.Eckert, A.Vigouroux, L.Lo Leggio, S.Moréra.
 
  ABSTRACT  
 
Alicyclobacillus acidocaldarius endoglucanase Cel9A (AaCel9A) is an inverting glycoside hydrolase with beta-1,4-glucanase activity on soluble polymeric substrates. Here, we report three X-ray structures of AaCel9A: a ligand-free structure at 1.8 A resolution and two complexes at 2.66 and 2.1 A resolution, respectively, with cellobiose obtained by co-crystallization and with cellotetraose obtained by the soaking method. AaCel9A forms an (alpha/alpha)(6)-barrel like other glycoside hydrolase family 9 enzymes. When cellobiose is used as a ligand, three glucosyl binding subsites are occupied, including two on the glycone side, while with cellotetraose as a ligand, five subsites, including four on the glycone side, are occupied. A structural comparison showed no conformational rearrangement of AaCel9A upon ligand binding. The structural analysis demonstrates that of the four minus subsites identified, subsites -1 and -2 show the strongest interaction with bound glucose. In conjunction with the open active-site cleft of AaCel9A, this is able to reconcile the previously observed cleavage of short-chain oligosaccharides with cellobiose as main product with the endo mode of action on larger polysaccharides.
 
  Selected figure(s)  
 
Figure 1.
Fig. 1. Ribbon representation of AaCel9A in complex with cellotetraose. The Ig-like domain is in orange, and the catalytic domain is in cyan/purple. The five glucosyl units (+ 1, − 1, − 2, − 3, and − 4) are shown in stick form colored green for carbon atoms and red for oxygen atoms. The zinc ion and the calcium ion bound to AaCel9A are shown in green and yellow sphere, respectively.
Figure 2.
Fig. 2. Glycosyl binding cleft (a) Cellobiose bound to the active-site cleft of AaCel9A in an F[o] − F[c] omit map contoured at 2.5 σ. Binding sites + 1, − 1, and − 2 are indicated, as are the corresponding aromatic stacking partners for the ligand. (b) Cellotetraose bound to the active site of AaCel9A in an F[o] − F[c] omit map contoured at 2.5 σ. Binding sites − 4 to + 1 are indicated, as are the corresponding aromatic stacking partners for the ligand. (c) Comparison of the glucosyl units on the minus subsites between AaCel9A (green), TfCel9A (cyan), and CcCel9G (purple). Residues Ile400 in AaCel9A, Asp311, and Trp256 in TfCel9A and Phe309 and Trp254 in CcCel9G are shown in stick form.
 
  The above figures are reprinted by permission from Elsevier: J Mol Biol (2009, 394, 61-70) copyright 2009.  
  Figures were selected by the author.