Insights into the glycosaminoglycan-mediated cytotoxic mechanism of eosinophil cationic protein revealed by NMR

M Flor García-Mayoral, Angeles Canales, Dolores Díaz, Javier López-Prados, Mohammed Moussaoui, José L de Paz, Jesús Angulo, Pedro M Nieto, Jesús Jiménez-Barbero, Ester Boix, Marta Bruix

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31 Citations (Scopus)


Protein-glycosaminoglycan interactions are essential in many biological processes and human diseases, yet how their recognition occurs is poorly understood. Eosinophil cationic protein (ECP) is a cytotoxic ribonuclease that interacts with glycosaminoglycans at the cell surface; this promotes the destabilization of the cellular membrane and triggers ECP's toxic activity. To understand this membrane destabilization event and the differences in the toxicity of ECP and its homologues, the high resolution solution structure of the complex between full length folded ECP and a heparin-derived trisaccharide (O-iPr-a-D-GlcNS6S-a(1-4)-L-IdoA2S-a(1-4)-D-GlcNS6S) has been solved by NMR methods and molecular dynamics simulations. The bound protein retains the tertiary structure of the free protein. The (2)S(0) conformation of the IdoA ring is preferably recognized by the protein. We have identified the precise location of the heparin binding site, dissected the specific interactions responsible for molecular recognition, and defined the structural requirements for this interaction. The structure reveals the contribution of Arg7, Gln14, and His15 in helix a1, Gln40 in strand ß1, His64 in loop 4, and His128 in strand ß6 in the recognition event and corroborates the previously reported participation of residues Arg34-Asn39. The participation of the catalytic triad (His15, Lys38, His128) in recognizing the heparin mimetic reveals, at atomic resolution, the mechanism of heparin's inhibition of ECP's ribonucleolytic activity. We have integrated all the available data to propose a molecular model for the membrane interaction process. The solved NMR complex provides the structural model necessary to design inhibitors to block ECP's toxicity implicated in eosinophil pathologies.
Original languageEnglish
Pages (from-to)144-1451
Number of pages8
JournalACS Chemical Biology
Issue number1
Publication statusPublished - 18 Jan 2013


  • Glycosaminoglycans
  • Models, Molecular
  • Humans
  • Cytotoxins
  • Protein Folding
  • Cell Membrane
  • Molecular Dynamics Simulation
  • Models, Biological
  • Magnetic Resonance Spectroscopy
  • Eosinophil Cationic Protein
  • Binding Sites

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