PDBsum entry 2uwf

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protein metals links
Hydrolase PDB id
Jmol PyMol
Protein chain
356 a.a. *
_CA ×4
Waters ×210
* Residue conservation analysis
PDB id:
Name: Hydrolase
Title: Crystal structure of family 10 xylanase from bacillus halodurans
Structure: Alkaline active endoxylanase. Chain: a. Fragment: residues 47-396. Synonym: endoxylanase. Engineered: yes. Other_details: additional his-tag present in this entry. I359d360h361h362h363h364h365h366
Source: Bacillus halodurans. Organism_taxid: 86665. Strain: s7. Expressed in: escherichia coli. Expression_system_taxid: 511693.
2.10Å     R-factor:   0.188     R-free:   0.241
Authors: G.Mamo,M.Thunnissen,R.Hatti-Kaul, B.Mattiasson
Key ref: G.Mamo et al. (2009). An alkaline active xylanase: insights into mechanisms of high pH catalytic adaptation. Biochimie, 91, 1187-1196. PubMed id: 19567261
21-Mar-07     Release date:   27-May-08    
Go to PROCHECK summary

Protein chain
Pfam   ArchSchema ?
P07528  (XYNA_BACHD) -  Endo-1,4-beta-xylanase A
396 a.a.
356 a.a.*
Key:    PfamA domain  Secondary structure  CATH domain
* PDB and UniProt seqs differ at 12 residue positions (black crosses)

 Enzyme reactions 
   Enzyme class: E.C.  - Endo-1,4-beta-xylanase.
[IntEnz]   [ExPASy]   [KEGG]   [BRENDA]
      Reaction: Endohydrolysis of 1,4-beta-D-xylosidic linkages in xylans.
 Gene Ontology (GO) functional annotation 
  GO annot!
  Cellular component     extracellular region   1 term 
  Biological process     metabolic process   4 terms 
  Biochemical function     hydrolase activity     4 terms  


Biochimie 91:1187-1196 (2009)
PubMed id: 19567261  
An alkaline active xylanase: insights into mechanisms of high pH catalytic adaptation.
G.Mamo, M.Thunnissen, R.Hatti-Kaul, B.Mattiasson.
The alkaliphilic bacterium, Bacillus halodurans S7, produces an alkaline active xylanase (EC, which differs from many other xylanases in being operationally stable under alkaline conditions as well as at elevated temperature. Compared to non-alkaline active xylanases, this enzyme has a high percent composition of acidic amino acids which results in high ratio of negatively to positively charged residues. A positive correlation was observed between the charge ratio and the pH optima of xylanases. The recombinant xylanase was crystallized using a hanging drop diffusion method. The crystals belong to the space group P2(1)2(1)2(1) and the structure was determined at a resolution of 2.1 A. The enzyme has the common eight-fold TIM-barrel structure of family 10 xylanases; however, unlike non-alkaline active xylanases, it has a highly negatively charged surface and a deeper active site cleft. Mutational analysis of non-conserved amino acids which are close to the acid/base residue has shown that Val169, Ile170 and Asp171 are important to hydrolyze xylan at high pH. Unlike the wild type xylanase which has optimum pH at 9-9.5, the triple mutant xylanase (V169A, I170F and D171N), which was constructed using sequence information of alkaline sensitive xylanses was optimally active around pH 7. Compared to non-alkaline active xylanases, the alkaline active xylanases have highly acidic surfaces and fewer solvent exposed alkali labile residues. Based on these results obtained from sequence, structural and mutational analysis, the possible mechanisms of high pH stability and catalysis are discussed. This will provide useful information to understand the mechanism of high pH adaptation and engineering of enzymes that can be operationally stable at high pH.

Literature references that cite this PDB file's key reference

  PubMed id Reference
20730475 G.Zhang, L.Mao, Y.Zhao, Y.Xue, and Y.Ma (2010).
Characterization of a thermostable xylanase from an alkaliphilic Bacillus sp.
  Biotechnol Lett, 32, 1915-1920.  
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