4B1M

CARBOHYDRATE BINDING MODULE CBM66 FROM BACILLUS SUBTILIS


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.1 Å
  • R-Value Free: 0.181 
  • R-Value Work: 0.156 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

How Nature Can Exploit Nonspecific Catalytic and Carbohydrate Binding Modules to Create Enzymatic Specificity

Cuskin, F.Flint, J.E.Gloster, T.M.Morland, C.Basle, A.Henrissat, B.Coutinho, P.M.Strazzulli, A.Solovyova, A.S.Davies, G.J.Gilbert, H.J.

(2012) Proc.Natl.Acad.Sci.USA 109: 20889

  • DOI: 10.1073/pnas.1212034109
  • Primary Citation of Related Structures:  4AZZ, 4B1L

  • PubMed Abstract: 
  • Noncatalytic carbohydrate binding modules (CBMs) are components of glycoside hydrolases that attack generally inaccessible substrates. CBMs mediate a two- to fivefold elevation in the activity of endo-acting enzymes, likely through increasing the con ...

    Noncatalytic carbohydrate binding modules (CBMs) are components of glycoside hydrolases that attack generally inaccessible substrates. CBMs mediate a two- to fivefold elevation in the activity of endo-acting enzymes, likely through increasing the concentration of the appended enzymes in the vicinity of the substrate. The function of CBMs appended to exo-acting glycoside hydrolases is unclear because their typical endo-binding mode would not fulfill a targeting role. Here we show that the Bacillus subtilis exo-acting β-fructosidase SacC, which specifically hydrolyses levan, contains the founding member of CBM family 66 (CBM66). The SacC-derived CBM66 (BsCBM66) targets the terminal fructosides of the major fructans found in nature. The crystal structure of BsCBM66 in complex with ligands reveals extensive interactions with the terminal fructose moiety (Fru-3) of levantriose but only limited hydrophobic contacts with Fru-2, explaining why the CBM displays broad specificity. Removal of BsCBM66 from SacC results in a ~100-fold reduction in activity against levan. The truncated enzyme functions as a nonspecific β-fructosidase displaying similar activity against β-2,1- and β-2,6-linked fructans and their respective fructooligosaccharides. Conversely, appending BsCBM66 to BT3082, a nonspecific β-fructosidase from Bacteroides thetaiotaomicron, confers exolevanase activity on the enzyme. We propose that BsCBM66 confers specificity for levan, a branched fructan, through an "avidity" mechanism in which the CBM and the catalytic module target the termini of different branches of the same polysaccharide molecule. This report identifies a unique mechanism by which CBMs modulate enzyme function, and shows how specificity can be tailored by integrating nonspecific catalytic and binding modules into a single enzyme.


    Organizational Affiliation

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




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
LEVANASE
A, B, C
185Bacillus subtilis (strain 168)Gene Names: sacC
EC: 3.2.1.80
Find proteins for P05656 (Bacillus subtilis (strain 168))
Go to UniProtKB:  P05656
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NA
Query on NA

Download SDF File 
Download CCD File 
A, B, C
SODIUM ION
Na
FKNQFGJONOIPTF-UHFFFAOYSA-N
 Ligand Interaction
SO4
Query on SO4

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Download CCD File 
B
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
FRU
Query on FRU

Download SDF File 
Download CCD File 
A, B, C
FRUCTOSE
C6 H12 O6
RFSUNEUAIZKAJO-ARQDHWQXSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.1 Å
  • R-Value Free: 0.181 
  • R-Value Work: 0.156 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 66.897α = 90.00
b = 36.909β = 90.61
c = 87.355γ = 90.00
Software Package:
Software NamePurpose
MOLREPphasing
REFMACrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2012-12-12
    Type: Initial release
  • Version 1.1: 2012-12-19
    Type: Database references
  • Version 1.2: 2013-01-16
    Type: Database references