Plant and animal intracellular nucleotide-binding, leucine-rich repeat (NLR) immune receptors detect pathogen-derived molecules and activate defense. Plant NLRs can be divided into several classes based upon their N-terminal signaling domains, including TIR (Toll-like, Interleukin-1 receptor, Resistance protein)- and CC (coiled-coil)-NLRs. Upon ligand detection, mammalian NAIP and NLRC4 NLRs oligomerize, forming an inflammasome that induces proximity of its N-terminal signaling domains. Recently, a plant CC-NLR was revealed to form an inflammasome-like hetero-oligomer. To further investigate plant NLR signaling mechanisms, we fused the N-terminal TIR domain of several plant NLRs to the N terminus of NLRC4. Inflammasome-dependent induced proximity of the TIR domain in planta initiated defense signaling. Thus, induced proximity of a plant TIR domain imposed by oligomerization of a mammalian inflammasome is sufficient to activate authentic plant defense. Ligand detection and inflammasome formation is maintained when the known components of the NLRC4 inflammasome is transferred across kingdoms, indicating that NLRC4 complex can robustly function without any additional mammalian proteins. Additionally, we found NADase activity of a plant TIR domain is necessary for plant defense activation, but NADase activity of a mammalian or a bacterial TIR is not sufficient to activate defense in plants.

植物和动物细胞内核苷酸结合的富含亮氨酸的重复（NLR）免疫受体可检测病原体衍生的分子并激活防御。植物NLR根据其N端信号域可分为几类，包括TIR（Toll样，白介素1受体，抗性蛋白）和CC（螺旋）-NLR。检测到配体后，哺乳动物NAIP和NLRC4 NL​​R寡聚，形成炎症小体，诱导其N端信号域的接近。最近，发现一种植物CC-NLR会形成类似炎症小体的杂聚体。为了进一步研究植物NLR信号传导机制，我们将几种植物NLR的N末端TIR结构域融合到NLRC4的N末端。植物体内TIR结构域的炎性体依赖性诱导的邻近启动了防御信号传导。从而，哺乳动物炎症小体的低聚作用引起的植物TIR结构域的诱导的邻近足以激活真实的植物防御。当NLRC4炎性小体的已知成分跨界转移时，配体检测和炎性小体的形成得以维持，这表明NLRC4复合物可以在没有任何其他哺乳动物蛋白的情况下稳定地发挥作用。此外，我们发现植物TIR结构域的NADase活性对于植物防御激活是必需的，但是哺乳动物或细菌TIR的NADase活性不足以激活植物防御。提示NLRC4复合物无需任何其他哺乳动物蛋白即可稳定发挥功能。此外，我们发现植物TIR结构域的NADase活性对于植物防御激活是必需的，但是哺乳动物或细菌TIR的NADase活性不足以激活植物防御。提示NLRC4复合物无需任何其他哺乳动物蛋白即可稳定发挥功能。此外，我们发现植物TIR结构域的NADase活性对于植物防御激活是必需的，但是哺乳动物或细菌TIR的NADase活性不足以激活植物防御。