title: Induced conformational change in human IL-4 upon binding of a signal-neutralizing DARPin.
abstract: The crystal structure of DARPin 44C12V5 that neutralizes IL-4 signaling has been determined alone and bound to human IL-4. A significant conformational change occurs in the IL-4 upon DARPin binding. The DARPin binds to the face of IL-4 formed by the A and C α-helices. The structure of the DARPin remains virtually unchanged. The conformational changes in IL-4 include a reorientation of the C-helix Trp91 side chain and repositioning of CD-loop residue Leu96. Both side chains move by >9 Å, becoming buried in the central hydrophobic region of the IL-4:DARPin interface. This hydrophobic region is surrounded by a ring of hydrophilic interactions comprised of hydrogen bonds and salt bridges and represents a classical "hotspot." The structures also reveal how the DARPin neutralizes IL-4 signaling. Comparing the IL-4:DARPin complex structure with the structures of IL-4 bound to its receptors (Hage et al., Cell 1999; 97, 271-281; La Porte et al., Cell 2008, 132, 259-272), it is found that the DARPin binds to the same IL-4 face that interacts with the junction of the D1 and D2 domains of the IL-4Rα receptors. Signaling is blocked since IL-4 cannot bind to this receptor, which it must do first before initiating a productive receptor complex with either the IL-13α1 or the γc receptor.
authors.affiliation: Janssen Research & Development, LLC, Biotechnology Center of Excellence, Spring House, Pennsylvania, 19477.
authors.forename: Galina
authors.initials: G
authors.lastname: Obmolova
authors.affiliation: Janssen Research & Development, LLC, Biotechnology Center of Excellence, Spring House, Pennsylvania, 19477.
authors.forename: Alexey
authors.initials: A
authors.lastname: Teplyakov
authors.affiliation: Janssen Research & Development, LLC, Biotechnology Center of Excellence, Spring House, Pennsylvania, 19477.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Malia
authors.affiliation: Janssen Research & Development, LLC, Biotechnology Center of Excellence, Spring House, Pennsylvania, 19477.
authors.forename: Edward
authors.initials: E
authors.lastname: Keough
authors.affiliation: Janssen Research & Development, LLC, Biotechnology Center of Excellence, Spring House, Pennsylvania, 19477.
authors.forename: Jinquan
authors.initials: J
authors.lastname: Luo
authors.affiliation: Janssen Research & Development, LLC, Biotechnology Center of Excellence, Spring House, Pennsylvania, 19477.
authors.forename: Raymond
authors.initials: R
authors.lastname: Sweet
authors.affiliation: Janssen Research & Development, LLC, Biotechnology Center of Excellence, Spring House, Pennsylvania, 19477.
authors.forename: Steven A
authors.initials: SA
authors.lastname: Jacobs
authors.affiliation: Janssen Research & Development, LLC, Biotechnology Center of Excellence, Spring House, Pennsylvania, 19477.
authors.forename: Fang
authors.initials: F
authors.lastname: Yi
authors.affiliation: Janssen Research & Development, LLC, Biotechnology Center of Excellence, Spring House, Pennsylvania, 19477.
authors.forename: Randi
authors.initials: R
authors.lastname: Hippensteel
authors.affiliation: Janssen Research & Development, LLC, Biotechnology Center of Excellence, Spring House, Pennsylvania, 19477.
authors.forename: Karyn T
authors.initials: KT
authors.lastname: O'Neil
authors.affiliation: Janssen Research & Development, LLC, Biotechnology Center of Excellence, Spring House, Pennsylvania, 19477.
authors.forename: Gary L
authors.initials: GL
authors.lastname: Gilliland
mesh_terms: D017089:Ankyrin Repeat; D006801:Humans; D015847:Interleukin-4 / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: C508598:IL4 protein, human; D011994:Recombinant Proteins; D015847:Interleukin-4
keywords: DARPin; IL-4:DARPin complex; alternative scaffold; x-ray structure