4NI7

Crystal structure of human interleukin 6 in complex with a modified nucleotide aptamer (SOMAMER SL1025)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.40 Å
  • R-Value Free: 0.260 
  • R-Value Work: 0.222 
  • R-Value Observed: 0.224 

Starting Model: experimental
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wwPDB Validation   3D Report Full Report


This is version 1.4 of the entry. See complete history


Literature

Crystal structure of interleukin-6 in complex with a modified nucleic Acid ligand.

Gelinas, A.D.Davies, D.R.Edwards, T.E.Rohloff, J.C.Carter, J.D.Zhang, C.Gupta, S.Ishikawa, Y.Hirota, M.Nakaishi, Y.Jarvis, T.C.Janjic, N.

(2014) J Biol Chem 289: 8720-8734

  • DOI: https://doi.org/10.1074/jbc.M113.532697
  • Primary Citation of Related Structures:  
    4NI7, 4NI9

  • PubMed Abstract: 

    IL-6 is a secreted cytokine that functions through binding two cell surface receptors, IL-6Rα and gp130. Because of its involvement in the progression of several chronic inflammatory diseases, IL-6 is a target of pharmacologic interest. We have recently identified a novel class of ligands called SOMAmers (S low Off-rate Modified Aptamers) that bind IL-6 and inhibit its biologic activity. SOMAmers exploit the chemical diversity of protein-like side chains assembled on flexible nucleic acid scaffolds, resulting in an expanded repertoire of intra- and intermolecular interactions not achievable with conventional aptamers. Here, we report the co-crystal structure of a high affinity SOMAmer (Kd = 0.20 nm) modified at the 5-position of deoxyuridine in a complex with IL-6. The SOMAmer, comprised of a G-quartet domain and a stem-loop domain, engages IL-6 in a clamp-like manner over an extended surface exhibiting close shape complementarity with the protein. The interface is characterized by substantial hydrophobic interactions overlapping the binding surfaces of the IL-6Rα and gp130 receptors. The G-quartet domain retains considerable binding activity as a disconnected autonomous fragment (Kd = 270 nm). A single substitution from our diversely modified nucleotide library leads to a 37-fold enhancement in binding affinity of the G-quartet fragment (Kd = 7.4 nm). The ability to probe ligand surfaces in this manner is a powerful tool in the development of new therapeutic reagents with improved pharmacologic properties. The SOMAmer·IL-6 structure also expands our understanding of the diverse structural motifs achievable with modified nucleic acid libraries and elucidates the nature with which these unique ligands interact with their protein targets.


  • Organizational Affiliation

    From the SomaLogic, Inc., Boulder, Colorado 80301.


Macromolecules

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Interleukin-6186Homo sapiensMutation(s): 0 
Gene Names: IL6IFNB2
UniProt & NIH Common Fund Data Resources
Find proteins for P05231 (Homo sapiens)
Explore P05231 
Go to UniProtKB:  P05231
PHAROS:  P05231
GTEx:  ENSG00000136244 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP05231
Sequence Annotations
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  • Reference Sequence
Find similar nucleic acids by:  (by identity cutoff)  |  3D Structure
Entity ID: 2
MoleculeChains LengthOrganismImage
SOMAmer SL102532N/A
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.40 Å
  • R-Value Free: 0.260 
  • R-Value Work: 0.222 
  • R-Value Observed: 0.224 
  • Space Group: P 32
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 50.23α = 90
b = 50.23β = 90
c = 103.63γ = 120
Software Package:
Software NamePurpose
PHASERphasing
REFMACrefinement
XDSdata reduction
XSCALEdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2014-01-22
    Type: Initial release
  • Version 1.1: 2014-02-12
    Changes: Database references
  • Version 1.2: 2014-04-09
    Changes: Database references
  • Version 1.3: 2016-06-01
    Changes: Structure summary
  • Version 1.4: 2023-09-20
    Changes: Data collection, Database references, Derived calculations, Refinement description