5J7K

Loop grafting onto a highly stable FN3 scaffold


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.46 Å
  • R-Value Free: 0.285 
  • R-Value Work: 0.259 
  • R-Value Observed: 0.261 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Circumventing the stability-function trade-off in an engineered FN3 domain.

Porebski, B.T.Conroy, P.J.Drinkwater, N.Schofield, P.Vazquez-Lombardi, R.Hunter, M.R.Hoke, D.E.Christ, D.McGowan, S.Buckle, A.M.

(2016) Protein Eng Des Sel 

  • DOI: 10.1093/protein/gzw046
  • Primary Citation of Related Structures:  
    5J7C, 5J7K

  • PubMed Abstract: 
  • The favorable biophysical attributes of non-antibody scaffolds make them attractive alternatives to monoclonal antibodies. However, due to the well-known stability-function trade-off, these gains tend to be marginal after functional selection. A notable example is the fibronectin Type III (FN3) domain, FNfn10, which has been previously evolved to bind lysozyme with 1 pM affinity (FNfn10-α-lys), but suffers from poor thermodynamic and kinetic stability ...

    The favorable biophysical attributes of non-antibody scaffolds make them attractive alternatives to monoclonal antibodies. However, due to the well-known stability-function trade-off, these gains tend to be marginal after functional selection. A notable example is the fibronectin Type III (FN3) domain, FNfn10, which has been previously evolved to bind lysozyme with 1 pM affinity (FNfn10-α-lys), but suffers from poor thermodynamic and kinetic stability. To explore this stability-function compromise further, we grafted the lysozyme-binding loops from FNfn10-α-lys onto our previously engineered, ultra-stable FN3 scaffold, FN3con. The resulting variant (FN3con-α-lys) bound lysozyme with a markedly reduced affinity, but retained high levels of thermal stability. The crystal structure of FNfn10-α-lys in complex with lysozyme revealed unanticipated interactions at the protein-protein interface involving framework residues of FNfn10-α-lys, thus explaining the failure to transfer binding via loop grafting. Utilizing this structural information, we redesigned FN3con-α-lys and restored picomolar binding affinity to lysozyme, while maintaining thermodynamic stability (with a thermal melting temperature 2-fold higher than that of FNfn10-α-lys). FN3con therefore provides an exceptional window of stability to tolerate deleterious mutations, resulting in a substantial advantage for functional design. This study emphasizes the utility of consensus design for the generation of highly stable scaffolds for downstream protein engineering studies.


    Organizational Affiliation

    Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
FN3con-a-lysA, B, C, D, E, F, G, H99synthetic constructMutation(s): 0 
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.46 Å
  • R-Value Free: 0.285 
  • R-Value Work: 0.259 
  • R-Value Observed: 0.261 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 50.22α = 90
b = 71.23β = 90.43
c = 126.141γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
iMOSFLMdata reduction
Aimlessdata scaling
PHASERphasing

Structure Validation

View Full Validation Report




Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2016-08-17
    Type: Initial release
  • Version 1.1: 2016-09-14
    Changes: Database references
  • Version 1.2: 2016-09-21
    Changes: Database references