title: Interactive sites in the MyD88 Toll/interleukin (IL) 1 receptor domain responsible for coupling to the IL1beta signaling pathway.
abstract: Myeloid differentiation factor MyD88 is the essential adaptor protein that integrates and transduces intracellular signals generated by multiple Toll-like receptors including receptor complex for interleukin (IL) 1beta, a key inflammatory cytokine. IL1beta receptor complex interacts with MyD88 via the Toll/IL1 receptor (TIR) domain. Here we report structure-function studies that help define the MyD88 TIR domain binding sites involved in IL1beta-induced protein-protein interactions. The MyD88 TIR domain, employed as a dominant negative inhibitor of IL1beta signaling to screen MyD88 TIR mutants, lost its suppressing activity upon truncation of its Box 3. Accordingly, mutations of Box 3 residues 285-286 reversed the dominant negative effect of the MyD88 TIR domain on IL1beta-induced and NFkappaB-dependent reporter gene activity and IL6 production. Moreover, mutations of residues 171 in helix alphaA, 195-197 in Box 2, and 275 in betaE-strand had similar functional effects. Strikingly, only mutations of residues 195-197 eliminated the TIR-TIR interaction of MyD88 and IL1 receptor accessory protein (IL1RAcP), whereas substitution of neighboring canonical Pro200 by His was without effect. Mutations in Box 2 and 3 prevented homotypic MyD88 oligomerization via TIR domain. Based on this structure-function analysis, a three-dimensional docking model of TIR-TIR interaction between MyD88 and IL1RAcP was developed.
authors.affiliation: Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2363, USA.
authors.forename: Chunsheng
authors.initials: C
authors.lastname: Li
authors.forename: Jozef
authors.initials: J
authors.lastname: Zienkiewicz
authors.forename: Jacek
authors.initials: J
authors.lastname: Hawiger
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000943:Antigens, Differentiation / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D015153:Blotting, Western; D002460:Cell Line; D004247:DNA / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D019084:Fluorescent Antibody Technique, Indirect; D005799:Genes, Dominant; D017930:Genes, Reporter; D006639:Histidine / Q000737:chemistry; D006801:Humans; D047468:Immunoprecipitation; D007375:Interleukin-1 / Q000378:metabolism*; D015850:Interleukin-6 / Q000378:metabolism; D008024:Ligands; D008156:Luciferases / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011392:Proline / Q000737:chemistry; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011956:Receptors, Cell Surface / Q000737:chemistry; D011971:Receptors, Immunologic / Q000737:chemistry* / Q000378:metabolism; D017472:Receptors, Interleukin-1 / Q000737:chemistry* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D051193:Toll-Like Receptors; D014162:Transfection
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000943:Antigens, Differentiation; D007375:Interleukin-1; D015850:Interleukin-6; D008024:Ligands; C507779:MYD88 protein, human; D008562:Membrane Glycoproteins; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; D017472:Receptors, Interleukin-1; D051193:Toll-Like Receptors; D006639:Histidine; D004247:DNA; D011392:Proline; D008156:Luciferases