Crystal Structure of Q683A mutant of Exo-1,3/1,4-beta-glucanase (ExoP) from Pseudoalteromonas sp. BB1

Experimental Data Snapshot

  • Resolution: 1.90 Å
  • R-Value Free: 0.190 
  • R-Value Work: 0.162 
  • R-Value Observed: 0.164 

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Structure and activity of exo-1,3/1,4-beta-glucanase from marine bacterium Pseudoalteromonas sp. BB1 showing a novel C-terminal domain

Nakatani, Y.Cutfield, S.M.Cowieson, N.P.Cutfield, J.F.

(2012) FEBS J 279: 464-478

  • DOI: https://doi.org/10.1111/j.1742-4658.2011.08439.x
  • Primary Citation of Related Structures:  
    3F95, 3RRX, 3USZ, 3UT0

  • PubMed Abstract: 

    Following the discovery of an exo-1,3/1,4-β-glucanase (glycoside hydrolase family 3) from a seaweed-associated bacterium Pseudoalteromonas sp. BB1, the recombinant three-domain protein (ExoP) was crystallized and its structure solved to 2.3 Å resolution. The first two domains of ExoP, both of which contribute to the architecture of the active site, are similar to those of the two-domain barley homologue β-d-glucan exohydrolase (ExoI) with a distinctive Trp-Trp clamp at the +1 subsite, although ExoI displays broader specificity towards β-glycosidic linkages. Notably, excision of the third domain of ExoP results in an inactive enzyme. Domain 3 has a β-sandwich structure and was shown by CD to be more temperature stable than the native enzyme. It makes relatively few contacts to domain 1 and none at all to domain 2. Two of the domain 3 residues involved at the interface, Q683 (forming one hydrogen bond) and Q676 (forming two hydrogen bonds) were mutated to alanine. Variant Q676A retained about half the activity of native ExoP, but the Q683A variant was severely attenuated. The crystal structure of Q683A-ExoP indicated that domain 3 was highly mobile and that Q683 is critical to the stabilization of ExoP by domain 3. Small-angle X-ray scattering data lent support to this proposal. Domain 3 does not appear to be an obvious carbohydrate-binding domain and is related neither in sequence nor structure to the additional domains characterized in other glycoside hydrolase 3 subgroups. Its major role appears to be for protein stability but it may also help orient substrate. Structural data are available in the Protein Data Bank under the accession numbers 3UT0, 3USZ, 3F95 and 3RRX.

  • Organizational Affiliation

    Department of Biochemistry, University of Otago, Dunedin, New Zealand.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Exo-1,3/1,4-beta-glucanase822Pseudoalteromonas sp. BB1Mutation(s): 1 
Gene Names: exoP
EC: 3.2.1
Find proteins for Q0QJA3 (Pseudoalteromonas sp. BB1)
Explore Q0QJA3 
Go to UniProtKB:  Q0QJA3
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ0QJA3
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.90 Å
  • R-Value Free: 0.190 
  • R-Value Work: 0.162 
  • R-Value Observed: 0.164 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 68.247α = 90
b = 178.601β = 90
c = 176.047γ = 90
Software Package:
Software NamePurpose
Blu-Icedata collection
XDSdata reduction
SCALAdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2011-12-21
    Type: Initial release
  • Version 1.1: 2014-03-12
    Changes: Database references
  • Version 1.2: 2023-11-01
    Changes: Data collection, Database references, Derived calculations, Refinement description