Biological Assembly 1  

 3D View: Structure | 1D-3D View | Electron Density | Validation Report | Ligand Interaction

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors and generated by PQS (software)

Macromolecule Content

• Total Structure Weight: 11.91 kDa 
• Atom Count: 909 
• Modelled Residue Count: 98 
• Deposited Residue Count: 98 
• Unique protein chains: 1

2C3G

Structure of CBM26 from Bacillus halodurans amylase

• PDB DOI: 10.2210/pdb2C3G/pdb

• Classification: CARBOHYDRATE-BINDING MODULE
• Organism(s): Alkalihalobacillus halodurans C-125
• Expression System: Escherichia coli BL21(DE3)
• Mutation(s): No 


• Deposited: 2005-10-07 Released: 2005-10-17 
• Deposition Author(s): Boraston, A.B., Healey, M., Klassen, J., Ficko-Blean, E., Lammerts Van Bueren, A., Law, V.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.00 Å
• R-Value Free: 0.302 
• R-Value Work: 0.226 
• R-Value Observed: 0.230 

Literature

A Structural and Functional Analysis of Alpha-Glucan Recognition by Family 25 and 26 Carbohydrate-Binding Modules Reveals a Conserved Mode of Starch Recognition

Boraston, A.B., Healey, M., Klassen, J., Ficko-Blean, E., Lammerts Van Bueren, A., Law, V.

(2006) J Biol Chem 281: 587

• PubMed: 16230347 
• DOI: 10.1074/jbc.M509958200
• Primary Citation of Related Structures:  
  2C3G, 2C3H, 2C3V, 2C3W, 2C3X


• PubMed Abstract: 
  

Starch-hydrolyzing enzymes lacking alpha-glucan-specific carbohydrate-binding modules (CBMs) typically have lowered activity on granular starch relative to their counterparts with CBMs. Thus, consideration of starch recognition by CBMs is a key factor in understanding granular starch hydrolysis. To this end, we have dissected the modular structure of the maltohexaose-forming amylase from Bacillus halodurans (C-125). This five-module protein comprises an N-terminal family 13 catalytic module followed in order by two modules of unknown function, a family 26 CBM (BhCBM26), and a family 25 CBM (BhCBM25). Here we present a comprehensive structure-function analysis of starch and alpha-glucooligosaccharide recognition by BhCBM25 and BhCBM26 using UV methods, isothermal titration calorimetry, and x-ray crystallography. The results reveal that the two CBMs bind alpha-glucooligosaccharides, particularly those containing alpha-1,6 linkages, with different affinities but have similar abilities to bind granular starch. Notably, these CBMs appear to recognize the same binding sites in granular starch. The enhanced affinity of the tandem CBMs for granular starch is suggested to be the main biological advantage for this enzyme to contain two CBMs. Structural studies of the native and ligand-bound forms of BhCBM25 and BhCBM26 show a structurally conserved mode of ligand recognition but through non-sequence-conserved residues. Comparison of these CBM structures with other starch-specific CBM structures reveals a generally conserved mode of starch recognition.

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Organizational Affiliation: 

Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada. [e-mail]

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
ALPHA-AMYLASE G-6	A	98	Alkalihalobacillus halodurans C-125	Mutation(s): 0  Gene Names: BH0413
UniProt
Find proteins for Q9KFR4 (Alkalihalobacillus halodurans (strain ATCC BAA-125 / DSM 18197 / FERM 7344 / JCM 9153 / C-125)) Explore Q9KFR4  Go to UniProtKB:  Q9KFR4

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
CD	B [auth A], C [auth A], D [auth A], E [auth A]	CADMIUM ION Cd WLZRMCYVCSSEQC-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.00 Å
• R-Value Free: 0.302 
• R-Value Work: 0.226 
• R-Value Observed: 0.230 
• Space Group: P 4₂ 2₁ 2

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 49.286	α = 90
b = 49.286	β = 90
c = 86.76	γ = 90

Software Package:

Software Name	Purpose
REFMAC	refinement

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2005-10-07 
• Released Date: 2005-10-17 
Deposition Author(s): Boraston, A.B., Healey, M., Klassen, J., Ficko-Blean, E., Lammerts Van Bueren, A., Law, V.

Revision History  

• Version 1.0: 2005-10-17
  Type: Initial release
  
• Version 1.1: 2011-05-07
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance