Identification of critical regions within the TIR domain of IL-1 receptor type I.
Interleukin-1 receptor type I (IL-1RI) belongs to a superfamily of proteins characterized by an intracellular Toll/IL-1 receptor (TIR) domain. This domain harbors three conserved regions called boxes 1-3 that play crucial roles in mediating IL-1 responses. Boxes 1 and 2 are considered to be involved in binding of adapter molecules. Amino acids possibly crucial for IL-1RI signaling were predicted via homology models of the IL-1RI TIR domain based on the crystal structure of IL-1RAPL. The role of ten of these residues was investigated by site-directed mutagenesis and a functional luciferase assay reflecting NF-κB activity in transiently transfected Jurkat cells. In particular, the mutants E437K/D438K, E472A/E473A and S465A/S470A/S471A/E472A/E473A showed decreased and the mutant E437A/D438A increased IL-1 responsiveness compared to the mouse IL-1RI wild type. In conclusion, the αC' helix (Q469-E473 in mouse IL-1RI) is probably involved in heterotypic interactions of IL-1RI with IL-1RAcP or MyD88.
Department of Internal Medicine I, University Clinic Regensburg, D-93042 Regensburg, Germany. Electronic address: raj10062@web.de.
Jürgen
J
Radons
Department of Internal Medicine I, University Clinic Regensburg, D-93042 Regensburg, Germany.
Werner
W
Falk
Institute of Pharmacy, University of Regensburg, D-93040 Regensburg, Germany.
Stefan
S
Dove
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D015870:Gene Expression; D017930:Genes, Reporter; D006801:Humans; D007375:Interleukin-1 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019169:Jurkat Cells; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D053594:Myeloid Differentiation Factor 88 / Q000235:genetics / Q000378:metabolism; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D053573:Receptors, Interleukin-1 Type I / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D040681:Structural Homology, Protein
C508590:IL1R1 protein, human; C583355:IL1R1 protein, mouse; D007375:Interleukin-1; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D053573:Receptors, Interleukin-1 Type I; D008156:Luciferases
Homology modeling; IL-1; IL-1RI; NF-κB; Site-directed mutagenesis; TIR domain