title: Non-canonical interleukin 23 receptor complex assembly: p40 protein recruits interleukin 12 receptor β1 via site II and induces p19/interleukin 23 receptor interaction via site III.
abstract: IL-23, composed of the cytokine subunit p19 and the soluble α receptor subunit p40, binds to a receptor complex consisting of the IL-23 receptor (IL-23R) and the IL-12 receptor β1 (IL-12Rβ1). Complex formation was hypothesized to follow the "site I-II-III" architectural paradigm, with site I of p19 being required for binding to p40, whereas sites II and III of p19 mediate binding to IL-12Rβ1 and IL-23R, respectively. Here we show that the binding mode of p19 to p40 and of p19 to IL-23R follow the canonical site I and III paradigm but that interaction of IL-23 to IL-12Rβ1 is independent of site II in p19. Instead, binding of IL-23 to the cytokine binding module of IL-12Rβ1 is mediated by domains 1 and 2 of p40 via corresponding site II amino acids of IL-12Rβ1. Moreover, domains 2 and 3 of p40 were sufficient for complex formation with p19 and to induce binding of p19 to IL-23R. The Fc-tagged fusion protein of p40_D2D3/p19 did, however, not act as a competitive IL-23 antagonist but, at higher concentrations, induced proliferation via IL-23R but independent of IL-12Rβ1. On the basis of our experimental validation, we propose a non-canonical topology of the IL-23·IL-23R·IL-12Rβ1 complex. Furthermore, our data help to explain why p40 is an antagonist of IL-23 and IL-12 signaling and show that site II of p19 is dispensable for IL-23 signaling.
authors.affiliation: From the Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich Heine University, 40225 Düsseldorf, Germany and.
authors.forename: Jutta
authors.initials: J
authors.lastname: Schröder
authors.affiliation: From the Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich Heine University, 40225 Düsseldorf, Germany and.
authors.forename: Jens M
authors.initials: JM
authors.lastname: Moll
authors.affiliation: From the Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich Heine University, 40225 Düsseldorf, Germany and.
authors.forename: Paul
authors.initials: P
authors.lastname: Baran
authors.affiliation: the Institute of Biochemistry, Medical Faculty, Christian Albrechts University, 24098 Kiel, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Grötzinger
authors.affiliation: From the Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich Heine University, 40225 Düsseldorf, Germany and jscheller@uni-duesseldorf.de.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Scheller
authors.affiliation: From the Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich Heine University, 40225 Düsseldorf, Germany and doreen.floss@uni-duesseldorf.de.
authors.forename: Doreen M
authors.initials: DM
authors.lastname: Floss
mesh_terms: D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D019556:COS Cells; D002460:Cell Line; D002522:Chlorocebus aethiops; D003412:Cricetulus; D015870:Gene Expression; D006801:Humans; D053711:Interleukin-12 Receptor beta 1 Subunit / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D053762:Interleukin-12 Subunit p40 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D053759:Interleukin-23 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D018123:Receptors, Interleukin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D053707:Receptors, Interleukin-12 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: C515500:IL23R protein, human; D053711:Interleukin-12 Receptor beta 1 Subunit; D053762:Interleukin-12 Subunit p40; D053759:Interleukin-23; D018123:Receptors, Interleukin; D053707:Receptors, Interleukin-12; D011993:Recombinant Fusion Proteins
keywords: Cytokine; Cytokine Action; Interleukin; Interleukin 12 Receptor; Interleukin 23; Interleukin 23 Receptor; Molecular Modeling; Mutagenesis; p19; p40