Interactive sites in the MyD88 toll/interleukin (IL) 1 receptor domain responsible for coupling to the IL1β signaling pathway
Interactive sites in the MyD88 toll/interleukin (IL) 1 receptor domain responsible for coupling to the IL1β signaling pathway
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DOI：
10.1074/jbc.m503262200
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发表时间：
2005-07-15
影响因子：
4.8
通讯作者：
Hawiger, J
中科院分区：
文献类型：
--
作者：
Li, CS;Zienkiewicz, J;Hawiger, J
髓样分化因子MyD 88是整合和转导由多种Toll样受体产生的细胞内信号的必需衔接蛋白，所述Toll样受体包括白细胞介素（IL）1 β（一种关键的炎性细胞因子）的受体复合物。IL 1 β受体复合物通过Toll/IL 1受体（TIR）结构域与MyD 88相互作用。在这里，我们报告的结构-功能的研究，帮助确定MyD 88 TIR结构域结合位点参与IL 1 β诱导的蛋白质-蛋白质相互作用。MyD 88 TIR结构域，用作IL 1 β信号传导的显性负抑制剂以筛选MyD 88 TIR突变体，在其框3截短后失去其抑制活性。因此，框3残基285-286的突变逆转了MyD 88 TIR结构域对IL 1 β诱导的和NF κ B依赖性报告基因活性和IL 6产生的显性负效应。此外，螺旋α A中的残基171、盒2中的残基195-197和β E-链中的残基275的突变具有相似的功能效应。引人注目的是，只有残基195-197的突变消除了MyD 88和IL 1受体辅助蛋白（IL 1 RAcP）的TIR-TIR相互作用，而相邻的典型Pro（200）被His取代则没有影响。框2和框3中的突变通过TIR结构域阻止同型MyD 88寡聚化。在此基础上，构建了MyD 88与IL 1 RAcP的TIR-TIR相互作用的三维对接模型。
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) 1 beta, a key inflammatory cytokine. IL1 beta 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 IL1 beta-induced protein-protein interactions. The MyD88 TIR domain, employed as a dominant negative inhibitor of IL1 beta 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 IL1 beta-induced and NF kappa B-dependent reporter gene activity and IL6 production. Moreover, mutations of residues 171 in helix alpha A, 195-197 in Box 2, and 275 in beta E-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 Pro(200) 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.