Amino acids conserved in interleukin-1 receptors (IL-1Rs) and the Drosophila toll protein are essential for IL-1R signal transduction

• Published in: The Journal of biological chemistry Vol. 267; no. 4; pp. 2605 - 2609
• Main Authors: Heguy, A, Baldari, C T, Macchia, G, Telford, J L, Melli, M
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 05-02-1992; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Sequence; Amino Acids - metabolism; Animals; Biological and medical sciences; Cell receptors; Cell structures and functions; Chromatography, Thin Layer; Drosophila; Drosophila Proteins; Escherichia coli - metabolism; Fundamental and applied biological sciences. Psychology; Humans; Insect Hormones - genetics; Insect Hormones - metabolism; interleukin 1; Interleukin-1 - metabolism; Membrane Glycoproteins - genetics; Membrane Glycoproteins - metabolism; Miscellaneous; Molecular and cellular biology; Molecular Sequence Data; Mutagenesis, Site-Directed; Receptors, Cell Surface; Receptors, Immunologic - genetics; Receptors, Immunologic - metabolism; Receptors, Interleukin-1; Recombinant Proteins - metabolism; Sequence Homology, Nucleic Acid; Signal Transduction; Toll-Like Receptors; Tumor Cells, Cultured; Insecta; Cytokine; Site directed mutagenesis; Homology; Drosophilidae; Signal transduction; Conserved sequence; Domain structure; Arthropoda; Interleukin 1; Invertebrata; Drosophila melanogaster; Diptera; Biological receptor
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)45924-8

The cytoplasmic domain of the human T cell-type interleukin-1 receptor (hIL-1R) is not involved in the binding, internalization, or nuclear localization of interleukin-1 (IL-1), but is essential for signal transduction. We have previously localized a 50-amino acid region (residues 477-527) critical for IL-1-mediated activation of the interleukin-2 promoter in T cells. This region displays a striking degree of amino acid conservation in human, murine, and chicken IL-1Rs. Here we report the results of a site-directed mutational analysis of the cytoplasmic domain of the hIL-1R. We have introduced single-amino acid substitutions at positions conserved in all three receptors and at nonconserved positions and identified key amino acids for IL-1R function in signal transduction. Three basic (Arg431, Lys515, and Arg518) and 3 aromatic (Phe513, Trp514, and Tyr519) amino acids that are conserved in human, murine, and chicken IL-1Rs could not be replaced without abolishing IL-1R-mediated signal transduction. A substitution at another conserved position (Pro521) reduces significantly the ability of the IL-1R to transmit the IL-1 signal. Nonconserved residues could be replaced without affecting signal transduction. The cytoplasmic domain of the IL-1R is related to that of the Drosophila Toll protein, with a 26% identity and a 43% similarity in amino acid sequence. The amino acids shown to be essential for IL-1R function are conserved in the Toll protein. Our experimental data indicate that the amino acid sequence similarity between the IL-1R and the Drosophila toll protein reflects a functional homology between the two proteins.