Vaccinia Virus Immunomodulator A46: Destructive Interactions with MAL and MyD88 Shown by Negative-Stain Electron Microscopy
Vaccinia Virus Immunomodulator A46: Destructive Interactions with MAL and MyD88 Shown by Negative-Stain Electron Microscopy
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DOI：
10.1016/j.str.2020.09.007
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发表时间：
2020-12-01
期刊：
影响因子：
5.7
通讯作者：
Skern, Tim
中科院分区：
文献类型：
--
作者：
Azar, Daniel F.;Haas, Meryl;Skern, Tim
痘苗病毒A46是痘病毒Bcl2样蛋白家族中的一种抗炎和非抗凋亡的双结构域成员，它在含有Toll/白细胞介素1受体(TIR)结构域的TLR接头蛋白MAL、MyD88、TRAM和TRIF的水平上抑制细胞的固有免疫反应。A46与其靶点的相互作用机制尚不清楚。MAL和MyD88的TIR结构域已被证明通过形成丝状组装来传递信号。我们通过负染色电子显微镜显示，在摩尔比为1：15的MAL和1：30的MyD88中，A46明显地依赖于浓度对这两个组件的破坏。利用定向突变和蛋白质-蛋白质交联，我们发现A46通过几个方面与MAL和MyD88相互作用，包括螺旋1和7上的残基以及C末端的柔性区域。我们提出了一个模型，在该模型中，A46以MAL和MyD88信号体链内界面为靶点，并以浓度依赖的方式逐渐破坏它们的组装。
Vaccinia virus A46 is an anti-inflammatory and non-anti-apoptotic, two-domain member of the poxviral Bcl-2-like protein family that inhibits the cellular innate immune response at the level of the Toll/interleukin-1 receptor (TIR) domain-containing TLR adaptor proteins MAL, MyD88, TRAM, and TRIF. The mechanism of interaction of A46 with its targets has remained unclear. The TIR domains of MAL and MyD88 have been shown to signal by forming filamentous assemblies. We show a clear concentration-dependent destruction of both of these assemblies by A46 by means of negative-stain electron microscopy from molar ratios of 1:15 for MAL and 1:30 for MyD88. Using targeted mutagenesis and protein-protein crosslinking, we show that A46 interacts with MAL and MyD88 through several facets, including residues on helices alpha 1 and alpha 7 and the C-terminal flexible region. We propose a model in which A46 targets the MAL and MyD88 signalosome intra-strand interfaces and gradually destroys their assemblies in a concentration-dependent manner.