2A9N

A Mutation Designed to Alter Crystal Packing Permits Structural Analysis of a Tight-binding Fluorescein-scFv complex


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.00 Å
  • R-Value Free: 0.266 
  • R-Value Work: 0.217 
  • R-Value Observed: 0.221 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

A mutation designed to alter crystal packing permits structural analysis of a tight-binding fluorescein-scFv complex.

Honegger, A.Spinelli, S.Cambillau, C.Pluckthun, A.

(2005) Protein Sci 14: 2537-2549

  • DOI: 10.1110/ps.051520605
  • Primary Citation of Related Structures:  
    2A9N, 2A9M

  • PubMed Abstract: 
  • The structure of the scFv fragment FITC-E2, obtained from a naive phage antibody scFv library derived from human donors, was determined at 2.1 A resolution in the free form and at 3.0 A in the complexed form. The wild-type (wt) scFv binds fluorescein ...

    The structure of the scFv fragment FITC-E2, obtained from a naive phage antibody scFv library derived from human donors, was determined at 2.1 A resolution in the free form and at 3.0 A in the complexed form. The wild-type (wt) scFv binds fluorescein with a K(D) of 0.75 nM. The free scFv readily crystallizes by compacting its 18 amino acid-long CDR-H3, partially occluding the binding site and further blocking access by binding to the "bottom" of a neighboring scFv molecule with a cluster of exposed aromatic residues within CDR-H3. Only upon mutating one of the residues involved in this dominant crystal contact, an exposed tryptophan in the middle of CDR-H3, crystals of the complex could be obtained. A series of alanine mutants within the putative antigen binding site, covering a range of binding affinities, were used to relate macroscopic thermodynamic and kinetic binding parameters to single-molecule disruption forces measured by AFM. The effects of the mutations on the binding properties, particularly on the fraction of binding-competent molecules within the population, cannot be fully explained by changes in the strength of local interactions. The significant conformational change of CDR-H3 between the free and the liganded form illustrates the plasticity of the binding site. An accompanying study in this issue by Curcio and colleagues presents the molecular dynamics simulation of the forced unbinding experiments and explores possible effects of the mutations on the unbinding pathway of the hapten.


    Organizational Affiliation

    Biochemisches Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
fluorescein-scfv light chainLM110Homo sapiensMutation(s): 0 
Protein Feature View
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  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
fluorescein-scfv heavy chainHI126Homo sapiensMutation(s): 0 
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ORE
Query on ORE

Download Ideal Coordinates CCD File 
H, I
4-(2,7-DIFLUORO-6-HYDROXY-3-OXO-3H-XANTHEN-9-YL)ISOPHTHALIC ACID
C21 H10 F2 O7
BRJCLSQFZSHLRL-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.00 Å
  • R-Value Free: 0.266 
  • R-Value Work: 0.217 
  • R-Value Observed: 0.221 
  • Space Group: P 21 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 81.382α = 90
b = 100.46β = 90
c = 61.749γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
DENZOdata reduction
CCP4data scaling
AMoREphasing

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-10-25
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance