9NKO | pdb_00009nko

Coevolved affibody pair A3B3


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.72 Å
  • R-Value Free: 
    0.251 (Depositor), 0.251 (DCC) 
  • R-Value Work: 
    0.205 (Depositor), 0.205 (DCC) 
  • R-Value Observed: 
    0.209 (Depositor) 

Starting Models: in silico
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wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Structural ontogeny of protein-protein interactions.

Yang, A.Jiang, H.Jude, K.M.Akpinaroglu, D.Allenspach, S.Li, A.J.Bowden, J.Perez, C.P.Liu, L.Huang, P.S.Kortemme, T.Listgarten, J.Garcia, K.C.

(2026) Science 391: eadx6931-eadx6931

  • DOI: https://doi.org/10.1126/science.adx6931
  • Primary Citation of Related Structures:  
    9NKM, 9NKN, 9NKO, 9NKP, 9NKQ, 9NKR, 9NKS

  • PubMed Abstract: 

    Understanding how protein binding sites evolve interactions with other proteins could hold clues to targeting "undruggable" surfaces. We used synthetic coevolution to engineer new interactions between naïve surfaces, simulating the de novo formation of protein complexes. We isolated seven distinct structural families of protein Z-domain complexes and found that synthetic complexes explore multiple shallow energy wells through ratchet-like docking modes, whereas complexes formed by natural binding sites converged in a deep energy well with a relatively fixed geometry. Epistasis analysis of a machine learning-estimated fitness landscape revealed "seed" contacts between binding partners that anchored the earliest stages of encounter complex formation. Our results suggest that "silent" surfaces have a shallower energy landscape than natural binding sites, disfavoring tight binding, likely owing to evolutionary counterselection.


  • Organizational Affiliation
    • Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.

Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A3 affibody
A, C
68synthetic constructMutation(s): 0 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Sequence Annotations
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  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
B3 affibody
B, D
68synthetic constructMutation(s): 0 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Sequence Annotations
Expand
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.72 Å
  • R-Value Free:  0.251 (Depositor), 0.251 (DCC) 
  • R-Value Work:  0.205 (Depositor), 0.205 (DCC) 
  • R-Value Observed: 0.209 (Depositor) 
Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 46.042α = 90
b = 42.076β = 93.99
c = 59.881γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
XDSdata reduction
XDSdata scaling
PHASERphasing

Structure Validation

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Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)United StatesGM150125
Howard Hughes Medical Institute (HHMI)United States--

Revision History  (Full details and data files)

  • Version 1.0: 2026-02-04
    Type: Initial release
  • Version 1.1: 2026-02-25
    Changes: Database references