背景回顾：Plant pathogen-activated immune signaling by nucleotide-binding leucine-rich repeat (NLR) receptors with an N-terminal Toll/Interleukin-1 receptor (TIR) domain converges on Enhanced Disease Susceptibility 1 (EDS1) and its direct partners Phytoalexin Deficient 4 (PAD4) or Senescence-Associated Gene 101 (SAG101). TIR-encoded NADases produce signaling molecules to promote exclusive EDS1-PAD4 and EDS1-SAG101 interactions with helper NLR sub-classes. 

结果1-含TIR蛋白催化形成信号分子：Here we show that TIR-containing proteins catalyze adenosine diphosphate (ADP)-ribosylation of adenosine triphosphate (ATP) and ADP ribose (ADPR) via ADPR polymerase-like and NADase activity, forming ADP-ribosylated ATP (ADPr-ATP) and ADPr-ADPR (di-ADPR), respectively. 

结果2-信号分子促进EDS1-SAG101与NRG1A的互作：Specific binding of ADPr-ATP or di-ADPR allosterically promotes EDS1-SAG101 interaction with helper NLR N requirement gene 1A (NRG1A) in vitro and in planta. 

结论：Our data reveal an enzymatic activity of TIRs that enables specific activation of the EDS1-SAG101-NRG1 immunity branch.

 摘 要 

在植物中，通过带有N端TIR结构域的核苷酸结合、富含亮氨酸重复（NLR）受体介导的植物病原菌激活免疫信号，依赖于EDS1及其直接互作蛋白PAD4或SAG101。TIR编码的NADases会产生信号分子，以促进EDS1-PAD4和EDS1-SAG101与helper NLRs的相互作用。本文中，作者发现含TIR结构域的蛋白能够通过ADPR聚合酶和NADase活性催化三磷酸腺苷（ATP）和二磷酸腺苷（ADP）核糖（ADPR）的ADP-核糖基化，分别形成ADPr-ATP和di-ADPR。在体外和植物体内的实验中，ADPr-ATP或di-ADPR的特异性结合能够通过别构作用，促进EDS1-SAG101与helper NLR蛋白NRG1A的互作。本文的研究结果揭示了TIR的一种酶活能够特异激活EDS1-SAG101-NRG1免疫分支。

 柴继杰