1W8Z

CBM29-2 mutant K85A: Probing the Mechanism of Ligand Recognition by Family 29 Carbohydrate Binding Modules


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.85 Å
  • R-Value Free: 0.211 
  • R-Value Work: 0.173 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Probing the Mechanism of Ligand Recognition in Family 29 Carbohydrate-Binding Modules

Flint, J.Bolam, D.N.Nurizzo, D.Taylor, E.J.Williamson, M.P.Walters, C.Davies, G.J.Gilbert, H.J.

(2005) J.Biol.Chem. 280: 23718

  • DOI: 10.1074/jbc.M501551200
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • The recycling of photosynthetically fixed carbon, by the action of microbial plant cell wall hydrolases, is integral to one of the major geochemical cycles and is of considerable industrial importance. Non-catalytic carbohydrate-binding modules (CBMs ...

    The recycling of photosynthetically fixed carbon, by the action of microbial plant cell wall hydrolases, is integral to one of the major geochemical cycles and is of considerable industrial importance. Non-catalytic carbohydrate-binding modules (CBMs) play a key role in this degradative process by targeting hydrolytic enzymes to their cognate substrate within the complex milieu of polysaccharides that comprise the plant cell wall. Family 29 CBMs have, thus far, only been found in an extracellular multienzyme plant cell wall-degrading complex from the anaerobic fungus Piromyces equi, where they exist as a CBM29-1:CBM29-2 tandem. Here we present both the structure of the CBM29-1 partner, at 1.5 A resolution, and examine the importance of hydrophobic stacking interactions as well as direct and solvent-mediated hydrogen bonds in the binding of CBM29-2 to different polysaccharides. CBM29 domains display unusual binding properties, exhibiting specificity for both beta-manno- and beta-gluco-configured ligands such as mannan, cellulose, and glucomannan. Mutagenesis reveals that "stacking" of tryptophan residues in the n and n+2 subsites plays a critical role in ligand binding, whereas the loss of tyrosine-mediated stacking in the n+4 subsite reduces, but does not abrogate, polysaccharide recognition. Direct hydrogen bonds to ligand, such as those provided by Arg-112 and Glu-78, play a pivotal role in the interaction with both mannan and cellulose, whereas removal of water-mediated interactions has comparatively little effect on carbohydrate binding. The interactions of CBM29-2 with the O2 of glucose or mannose contribute little to binding affinity, explaining why this CBM displays dual gluco/manno specificity.


    Organizational Affiliation

    Institute for Cell and Molecular Biosciences, University of Newcastle upon Tyne, Newcastle upon Tyne NE2 4HH, United Kingdom.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
NON CATALYTIC PROTEIN 1
A, B
149Piromyces equiMutation(s): 1 
Gene Names: ncp1
Find proteins for Q9C171 (Piromyces equi)
Go to UniProtKB:  Q9C171
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.85 Å
  • R-Value Free: 0.211 
  • R-Value Work: 0.173 
  • Space Group: P 43 21 2
Unit Cell:
Length (Å)Angle (°)
a = 93.040α = 90.00
b = 93.040β = 90.00
c = 83.188γ = 90.00
Software Package:
Software NamePurpose
AMoREphasing
REFMACrefinement
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-03-22
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Advisory, Version format compliance