Identification of an Arg-Leu-Arg tripeptide that contributes to the binding interface between the cytokine MIF and the chemokine receptor CXCR4

Sci Rep. 2018 Mar 26;8(1):5171. doi: 10.1038/s41598-018-23554-5.


MIF is a chemokine-like cytokine that plays a role in the pathogenesis of inflammatory and cardiovascular disorders. It binds to the chemokine-receptors CXCR2/CXCR4 to trigger atherogenic leukocyte migration albeit lacking canonical chemokine structures. We recently characterized an N-like-loop and the Pro-2-residue of MIF as critical molecular determinants of the CXCR4/MIF binding-site and identified allosteric agonism as a mechanism that distinguishes CXCR4-binding to MIF from that to the cognate ligand CXCL12. By using peptide spot-array technology, site-directed mutagenesis, structure-activity-relationships, and molecular docking, we identified the Arg-Leu-Arg (RLR) sequence-region 87-89 that - in three-dimensional space - 'extends' the N-like-loop to control site-1-binding to CXCR4. Contrary to wildtype MIF, mutant R87A-L88A-R89A-MIF fails to bind to the N-terminal of CXCR4 and the contribution of RLR to the MIF/CXCR4-interaction is underpinned by an ablation of MIF/CXCR4-specific signaling and reduction in CXCR4-dependent chemotactic leukocyte migration of the RLR-mutant of MIF. Alanine-scanning, functional competition by RLR-containing peptides, and molecular docking indicate that the RLR residues directly participate in contacts between MIF and CXCR4 and highlight the importance of charge-interactions at this interface. Identification of the RLR region adds important structural information to the MIF/CXCR4 binding-site that distinguishes this interface from CXCR4/CXCL12 and will help to design MIF-specific drug-targeting approaches.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Cardiovascular Diseases / genetics
  • Cardiovascular Diseases / pathology
  • Chemotaxis / genetics
  • Humans
  • Inflammation / genetics
  • Inflammation / pathology
  • Intramolecular Oxidoreductases / chemistry
  • Intramolecular Oxidoreductases / genetics*
  • Ligands
  • Macrophage Migration-Inhibitory Factors / chemistry
  • Macrophage Migration-Inhibitory Factors / genetics*
  • Molecular Docking Simulation
  • Peptides / chemistry
  • Peptides / genetics
  • Protein Binding / genetics*
  • Receptors, CXCR4 / chemistry
  • Receptors, CXCR4 / genetics*
  • Receptors, Interleukin-8B / chemistry
  • Receptors, Interleukin-8B / genetics
  • Structure-Activity Relationship*


  • CXCR2 protein, human
  • CXCR4 protein, human
  • Ligands
  • Macrophage Migration-Inhibitory Factors
  • Peptides
  • Receptors, CXCR4
  • Receptors, Interleukin-8B
  • Intramolecular Oxidoreductases
  • MIF protein, human