3OEA

Crystal structure of the Q121E mutants of C.polysaccharolyticus CBM16-1 bound to cellopentaose


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.35 Å
  • R-Value Free: 0.204 
  • R-Value Work: 0.175 
  • R-Value Observed: 0.176 

wwPDB Validation   3D Report Full Report


This is version 2.0 of the entry. See complete history


Literature

Mutational insights into the roles of amino acid residues in ligand binding for two closely related family 16 carbohydrate binding modules.

Su, X.Agarwal, V.Dodd, D.Bae, B.Mackie, R.I.Nair, S.K.Cann, I.K.

(2010) J Biol Chem 285: 34665-34676

  • DOI: 10.1074/jbc.M110.168302
  • Primary Citation of Related Structures:  
    3OEA, 3OEB

  • PubMed Abstract: 
  • Carbohydrate binding modules (CBMs) are specialized proteins that bind to polysaccharides and oligosaccharides. Caldanaerobius polysaccharolyticus Man5ACBM16-1/CBM16-2 bind to glucose-, mannose-, and glucose/mannose-configured substrates. The crystal structures of the two proteins represent the only examples in CBM family 16, and studies that evaluate the roles of amino acid residues in ligand binding in this family are lacking ...

    Carbohydrate binding modules (CBMs) are specialized proteins that bind to polysaccharides and oligosaccharides. Caldanaerobius polysaccharolyticus Man5ACBM16-1/CBM16-2 bind to glucose-, mannose-, and glucose/mannose-configured substrates. The crystal structures of the two proteins represent the only examples in CBM family 16, and studies that evaluate the roles of amino acid residues in ligand binding in this family are lacking. In this study, we probed the roles of amino acids (selected based on CBM16-1/ligand co-crystal structures) on substrate binding. Two tryptophan (Trp-20 and Trp-125) and two glutamine (Gln-81 and Gln-93) residues are shown to be critical in ligand binding. Additionally, several polar residues that flank the critical residues also contribute to ligand binding. The CBM16-1 Q121E mutation increased affinity for all substrates tested, whereas the Q21G and N97R mutants exhibited decreased substrate affinity. We solved CBM/substrate co-crystal structures to elucidate the molecular basis of the increased substrate binding by CBM16-1 Q121E. The Gln-121, Gln-21, and Asn-97 residues can be manipulated to fine-tune ligand binding by the Man5A CBMs. Surprisingly, none of the eight residues investigated was absolutely conserved in CBM family 16. Thus, the critical residues in the Man5A CBMs are either not essential for substrate binding in the other members of this family or the two CBMs are evolutionarily distinct from the members available in the current protein database. Man5A is dependent on its CBMs for robust activity, and insights from this study should serve to enhance our understanding of the interdependence of its catalytic and substrate binding modules.


    Organizational Affiliation

    Energy Biosciences Institute, Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
S-layer associated multidomain endoglucanaseA, B146Caldanaerobius polysaccharolyticusMutation(s): 1 
Gene Names: celA
UniProt
Find proteins for Q9ZA17 (Caldanaerobius polysaccharolyticus)
Explore Q9ZA17 
Go to UniProtKB:  Q9ZA17
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9ZA17
Protein Feature View
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  • Reference Sequence
Oligosaccharides

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Entity ID: 2
MoleculeChainsChain Length2D DiagramGlycosylation3D Interactions
beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-alpha-D-glucopyranoseC, D 5N/A Oligosaccharides Interaction
Glycosylation Resources
GlyTouCan:  G75287MT
GlyCosmos:  G75287MT
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

Download Ideal Coordinates CCD File 
E [auth A],
F [auth B]
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.35 Å
  • R-Value Free: 0.204 
  • R-Value Work: 0.175 
  • R-Value Observed: 0.176 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 32.393α = 62.5
b = 48.375β = 85.11
c = 48.985γ = 86.22
Software Package:
Software NamePurpose
MAR345dtbdata collection
PHASERphasing
REFMACrefinement
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-08-25
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 2.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Advisory, Atomic model, Data collection, Database references, Derived calculations, Structure summary