Identification of critical regions within the TIR domain of IL-1 receptor type I

Int J Biochem Cell Biol. 2015 Nov:68:15-20. doi: 10.1016/j.biocel.2015.08.009. Epub 2015 Aug 14.

Abstract

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.

Keywords: Homology modeling; IL-1; IL-1RI; NF-κB; Site-directed mutagenesis; TIR domain.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Gene Expression
  • Genes, Reporter
  • Humans
  • Interleukin-1 / chemistry*
  • Interleukin-1 / genetics
  • Interleukin-1 / metabolism
  • Jurkat Cells
  • Luciferases / genetics
  • Luciferases / metabolism
  • Mice
  • Models, Molecular
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Mutation
  • Myeloid Differentiation Factor 88 / genetics
  • Myeloid Differentiation Factor 88 / metabolism
  • NF-kappa B / genetics
  • NF-kappa B / metabolism
  • Protein Binding
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Receptors, Interleukin-1 Type I / chemistry*
  • Receptors, Interleukin-1 Type I / genetics
  • Receptors, Interleukin-1 Type I / metabolism
  • Sequence Alignment
  • Structural Homology, Protein

Substances

  • IL1R1 protein, human
  • IL1R1 protein, mouse
  • Interleukin-1
  • Myd88 protein, mouse
  • Myeloid Differentiation Factor 88
  • NF-kappa B
  • Receptors, Interleukin-1 Type I
  • Luciferases