title: Conformational nanobodies reveal tethered epidermal growth factor receptor involved in EGFR/ErbB2 predimers.
abstract: The epidermal growth factor receptor (EGFR) is a cell-surface receptor with a single transmembrane domain and tyrosine kinase activity carried by the intracellular domain. This receptor is one of the four members of the ErbB family including ErbB2, ErbB3, and ErbB4. Ligand binding, like EGF binding, induces a conformational rearrangement of the receptor and induces a homo/hetero dimerization essentially with ErbB family receptors that leads to the phosphorylation of the kinase domain, triggering a signaling cascade. EGFR can also form inactive dimers in a ligand-independent way through interactions between cytoplasmic domains. To date, the conformation of EGFR extracellular domain engaged in these inactive dimers remains unclear. In this study, we describe the successful selection and characterization of llama anti-EGFR nanobodies and their use as innovative conformational sensors. We isolated three different specific anti-EGFR clones binding to three distinct epitopes. Interestingly, the binding of all three nanobodies was found highly sensitive to ligand stimulation. Two nanobodies, D10 and E10, can only bind the ligand-free EGFR conformation characterized by an intramolecular tether between domains II and IV, whereas nanobody G10 binds both ligand-free and ligand activated EGFR, with an 8-fold higher affinity for the extended conformation in the presence of ligand. Here we took advantage of these conformational probes to reveal the existence of tethered EGFR in EGFR/ErbB2 predimers. These biosensors represent important tools allowing the determination of EGFR conformations and should help the design of relevant inhibitors.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale , U1068, Centre de Recherche en Cancérologie de Marseille, Marseille F-13009, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Nevoltris
authors.forename: Benjamin
authors.initials: B
authors.lastname: Lombard
authors.forename: Elodie
authors.initials: E
authors.lastname: Dupuis
authors.forename: Gérard
authors.initials: G
authors.lastname: Mathis
authors.forename: Patrick
authors.initials: P
authors.lastname: Chames
authors.forename: Daniel
authors.initials: D
authors.lastname: Baty
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D001665:Binding Sites; D015374:Biosensing Techniques; D002161:Camelids, New World; D002460:Cell Line; D000939:Epitopes / Q000276:immunology; D066246:ErbB Receptors / Q000737:chemistry* / Q000276:immunology*; D006801:Humans; D051379:Mice; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000737:chemistry*; D061905:Single-Domain Antibodies / Q000276:immunology*
chemical_list: D000939:Epitopes; D066246:ErbB Receptors; D018719:Erb-b2 Receptor Tyrosine Kinases; D061905:Single-Domain Antibodies
keywords: biosensors; conformational changes; epidermal growth factor receptor (EGFR); homogenous time-resolved fluorescence; nanobodies; phage display; single domain antibodies