Ullah M Obayed, Ve Thomas, Mangan Matthew, Alaidarous Mohammed, Sweet Matthew J, Mansell Ashley, Kobe Bostjan
School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia.
Acta Crystallogr D Biol Crystallogr. 2013 Dec;69(Pt 12):2420-30. doi: 10.1107/S0907444913022385. Epub 2013 Nov 19.
TRIF/TICAM-1 (TIR domain-containing adaptor inducing interferon-β/TIR domain-containing adaptor molecule 1) is the adaptor protein in the Toll-like receptor (TLR) 3 and 4 signalling pathway that leads to the production of type 1 interferons and cytokines. The signalling involves TIR (Toll/interleukin-1 receptor) domain-dependent TRIF oligomerization. A protease-resistant N-terminal region is believed to be involved in self-regulation of TRIF by interacting with its TIR domain. Here, the structural and functional characterization of the N-terminal domain of TRIF (TRIF-NTD) comprising residues 1-153 is reported. The 2.22 Å resolution crystal structure was solved by single-wavelength anomalous diffraction (SAD) using selenomethionine-labelled crystals of TRIF-NTD containing two additional introduced Met residues (TRIF-NTDA66M/L113M). The structure consists of eight antiparallel helices that can be divided into two subdomains, and the overall fold shares similarity to the interferon-induced protein with tetratricopeptide repeats (IFIT) family of proteins, which are involved in both the recognition of viral RNA and modulation of innate immune signalling. Analysis of TRIF-NTD surface features and the mapping of sequence conservation onto the structure suggest several possible binding sites involved in either TRIF auto-regulation or interaction with other signalling molecules or ligands. TRIF-NTD suppresses TRIF-mediated activation of the interferon-β promoter, as well as NF-κB-dependent reporter-gene activity. These findings thus identify opportunities for the selective targeting of TLR3- and TLR4-mediated inflammation.
TRIF/TICAM-1（含TIR结构域的衔接蛋白，可诱导干扰素-β/含TIR结构域的衔接分子1）是Toll样受体（TLR）3和4信号通路中的衔接蛋白，该信号通路可导致1型干扰素和细胞因子的产生。该信号传导涉及TIR（Toll/白细胞介素-1受体）结构域依赖性的TRIF寡聚化。据信，一个抗蛋白酶的N端区域通过与其TIR结构域相互作用参与TRIF的自我调节。在此，报道了包含1-153位残基的TRIF N端结构域（TRIF-NTD）的结构和功能特征。通过单波长反常衍射（SAD）解析了分辨率为2.22 Å的晶体结构，使用的是含有两个额外引入的Met残基（TRIF-NTDA66M/L113M）的硒代甲硫氨酸标记的TRIF-NTD晶体。该结构由八个反平行螺旋组成，可分为两个亚结构域，其整体折叠与含四肽重复序列的干扰素诱导蛋白（IFIT）家族的蛋白质相似，该家族蛋白参与病毒RNA的识别和先天免疫信号的调节。对TRIF-NTD表面特征的分析以及序列保守性在结构上的映射表明，存在几个可能参与TRIF自我调节或与其他信号分子或配体相互作用的结合位点。TRIF-NTD抑制TRIF介导的干扰素-β启动子的激活以及NF-κB依赖性报告基因的活性。因此，这些发现确定了选择性靶向TLR3和TLR4介导的炎症的机会。
