title: IRAK4 dimerization and trans-autophosphorylation are induced by Myddosome assembly.
abstract: Trans-autophosphorylation is among the most prevalent means of protein kinase activation, yet its molecular basis is poorly defined. In Toll-like receptor and interleukin-1 receptor signaling pathways, the kinase IRAK4 is recruited to the membrane-proximal adaptor MyD88 through death domain (DD) interactions, forming the oligomeric Myddosome and mediating NF-κB activation. Here we show that unphosphorylated IRAK4 dimerizes in solution with a KD of 2.5 μM and that Myddosome assembly greatly enhances IRAK4 kinase domain (KD) autophosphorylation at sub-KD concentrations. The crystal structure of the unphosphorylated IRAK4(KD) dimer captures a conformation that appears to represent the actual trans-autophosphorylation reaction, with the activation loop phosphosite of one IRAK4 monomer precisely positioned for phosphotransfer by its partner. We show that dimerization is crucial for IRAK4 autophosphorylation in vitro and ligand-dependent signaling in cells. These studies identify a mechanism for oligomerization-driven allosteric autoactivation of IRAK4 that may be general to other kinases activated by autophosphorylation.
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Weill Cornell Graduate School of Medical Sciences, New York, NY 10065, USA.
authors.forename: Ryan
authors.initials: R
authors.lastname: Ferrao
authors.affiliation: Department of Immunology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhou
authors.affiliation: D.E. Shaw Research, New York, NY 10036, USA.
authors.forename: Yibing
authors.initials: Y
authors.lastname: Shan
authors.affiliation: New York Structural Biology Center, National Synchrotron Light Source X4, Brookhaven National Laboratory, Upton, NY 11961, USA.
authors.forename: Qun
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA.
authors.forename: Qiubai
authors.initials: Q
authors.lastname: Li
authors.affiliation: D.E. Shaw Research, New York, NY 10036, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
authors.forename: David E
authors.initials: DE
authors.lastname: Shaw
authors.affiliation: Department of Immunology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Weill Cornell Graduate School of Medical Sciences, New York, NY 10065, USA. Electronic address: hao.wu@childrens.harvard.edu.
authors.forename: Hao
authors.initials: H
authors.lastname: Wu
mesh_terms: D020134:Catalytic Domain; D002478:Cells, Cultured; D006801:Humans; D053592:Interleukin-1 Receptor-Associated Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D053594:Myeloid Differentiation Factor 88 / Q000737:chemistry* / Q000378:metabolism*; D010766:Phosphorylation; D011487:Protein Conformation; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D012542:Scattering, Radiation; D013379:Substrate Specificity
chemical_list: C507779:MYD88 protein, human; D053594:Myeloid Differentiation Factor 88; C507773:IRAK4 protein, human; D053592:Interleukin-1 Receptor-Associated Kinases