PDBsum entry 2qno

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Hydrolase PDB id
Protein chain
629 a.a. *
Waters ×412
* Residue conservation analysis
PDB id:
Name: Hydrolase
Title: Crystal structure of the mutant e55q of the cellulase cel48f in complex with a thio-oligosaccharide
Structure: Endoglucanase f. Chain: a. Fragment: catalytic module. Synonym: endo-1,4-beta-glucanase f, cellulase f, egccf. Engineered: yes. Mutation: yes
Source: Clostridium cellulolyticum. Organism_taxid: 1521. Gene: celccf. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.
2.00Å     R-factor:   0.140     R-free:   0.182
Authors: G.Parsiegla,R.Haser
Key ref:
G.Parsiegla et al. (2008). Structures of mutants of cellulase Cel48F of Clostridium cellulolyticum in complex with long hemithiocellooligosaccharides give rise to a new view of the substrate pathway during processive action. J Mol Biol, 375, 499-510. PubMed id: 18035374 DOI: 10.1016/j.jmb.2007.10.039
19-Jul-07     Release date:   15-Jan-08    
Go to PROCHECK summary

Protein chain
Pfam   ArchSchema ?
P37698  (GUNF_CLOCE) -  Endoglucanase F
722 a.a.
629 a.a.*
Key:    PfamA domain  Secondary structure  CATH domain
* PDB and UniProt seqs differ at 1 residue position (black cross)

 Enzyme reactions 
   Enzyme class: E.C.  - 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   4 terms 
  Biochemical function     catalytic activity     5 terms  


DOI no: 10.1016/j.jmb.2007.10.039 J Mol Biol 375:499-510 (2008)
PubMed id: 18035374  
Structures of mutants of cellulase Cel48F of Clostridium cellulolyticum in complex with long hemithiocellooligosaccharides give rise to a new view of the substrate pathway during processive action.
G.Parsiegla, C.Reverbel, C.Tardif, H.Driguez, R.Haser.
An efficient breakdown of lignocellulosic biomass is a prerequisite for the production of second-generation biofuels. Cellulases are key enzymes in this process. We crystallized complexes between hemithio-cello-deca and dodecaoses and the inactive mutants E44Q and E55Q of the endo-processive cellulase Cel48F, one of the most abundant cellulases in cellulosomes from Clostridium cellulolyticum, to elucidate its processive mechanism. In both complexes, the cellooligosaccharides occupy similar positions in the tunnel part of the active site but are more or less buried into the cleft, which hosts the active site. In the E44Q complex, it proceeds along the upper part of the cavity, while it occupies in the E55Q complex the same productive binding subsites in the lower part of the cavity that have previously been reported in Cel48F/cellooligosaccharide complexes. In both cases, the sugar moieties are stabilized by stacking interactions with aromatic side chains and H bonds. The upper pathway is gated by Tyr403, which blocks its access in the E55Q complex and offers a new stacking interaction in the E44Q complex. The new structural data give rise to the hypothesis of a two-step mechanism in which processive action and chain disruption occupy different subsites at the end of their trajectory. In the first part of the mechanism, the chain may smoothly slide up to the leaving group site along the upper pathway, while in the second part, the chain is cleaved in the already described productive binding position located in the lower pathway. The solved native structure of Cel48F without any bound sugar in the active site confirms the two side-chain orientations of the proton donor Glu55 as observed in the complex structures.
  Selected figure(s)  
Figure 4.
Fig. 4. Hydrogen-bonding network of the hemithiocellooligosaccharide with the mutated enzyme E44Q. Distances are indicated in angstroms. Residues that perform stacking interactions with the sugar chain are drawn in thicker lines.
Figure 5.
Fig. 5. Hydrogen-bonding network around the proposed proton donor Glu55 as observed in the E44Q/hemithiocellooligosaccharide structure (a) and in the E55Q/hemithiocellooligosaccharide complex (b). Red spheres are water molecules; sugar moieties from the hemithiocellooligosaccharide are colored orange.
  The above figures are reprinted by permission from Elsevier: J Mol Biol (2008, 375, 499-510) copyright 2008.  
  Figures were selected by an automated process.  

Literature references that cite this PDB file's key reference

  PubMed id Reference
20373916 C.M.Fontes, and H.J.Gilbert (2010).
Cellulosomes: highly efficient nanomachines designed to deconstruct plant cell wall complex carbohydrates.
  Annu Rev Biochem, 79, 655-681.  
20967294 M.Saharay, H.Guo, and J.C.Smith (2010).
Catalytic mechanism of cellulose degradation by a cellobiohydrolase, CelS.
  PLoS One, 5, e12947.  
19622857 J.H.Pereira, R.Sapra, J.V.Volponi, C.L.Kozina, B.Simmons, and P.D.Adams (2009).
Structure of endoglucanase Cel9A from the thermoacidophilic Alicyclobacillus acidocaldarius.
  Acta Crystallogr D Biol Crystallogr, 65, 744-750.
PDB code: 3ez8
19193645 T.Ishida, S.Fushinobu, R.Kawai, M.Kitaoka, K.Igarashi, and M.Samejima (2009).
Crystal structure of glycoside hydrolase family 55 {beta}-1,3-glucanase from the basidiomycete Phanerochaete chrysosporium.
  J Biol Chem, 284, 10100-10109.
PDB codes: 3eqn 3eqo
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