, 50, Banerjee para road, Naihati, 743165, West Bengal, India.
Department of Botany, Narajole Raj College, Narajole, Paschim Medinipur, 721211, West Bengal, India.
Planta. 2020 Nov 12;252(6):101. doi: 10.1007/s00425-020-03512-0.
In this review, we have included evolution of plant intracellular immune receptors, oligomeric complex formation, enzymatic action, engineering, and mechanisms of immune inspection for appropriate defense outcomes. NLR (Nucleotide binding oligomerization domain containing leucine-rich repeat) proteins are the intracellular immune receptors that recognize pathogen-derived virulence factors to confer effector-triggered immunity (ETI). Activation of plant defense by the NLRs are often conveyed through N-terminal Toll-like/ IL-1 receptor (TIR) or non-TIR (coiled-coils or CC) domains. Homodimerization or self-association property of CC/ TIR domains of plant NLRs contribute to their auto-activity and induction of in planta ectopic cell death. High resolution crystal structures of Arabidopsis thaliana RPS4, L6, SNC1, RPP1 and Muscadinia rotundifolia RPV1 showed that interaction is mediated through one or two distinct interfaces i.e., αA and αE helices comprise AE interface and αD and αE helices were found to form DE interface. By contrast, conserved helical regions were determined for CC domains of plant NLRs. Evolutionary history of NLRs diversification has shown that paired forms were originated from NLR singletons. Plant TIRs executed NAD hydrolysis activity for cell death promotion. Plant NLRs were found to form large oligomeric complexes as observed in animal inflammasomes. We have also discussed different protein engineering methods includes domain shuffling, and decoy modification that increase effector recognition spectrum of plant NLRs. In summary, our review highlights structural basis of perception of the virulence factors by NLRs or NLR pairs to design novel classes of plant immune receptors.
在这篇综述中，我们纳入了植物细胞内免疫受体的进化、寡聚复合物的形成、酶的作用、工程设计以及免疫检查的机制，以获得适当的防御效果。NLR（核苷酸结合寡聚化结构域富含亮氨酸重复序列）蛋白是识别病原体来源的毒力因子的细胞内免疫受体，赋予效应子触发免疫（ETI）。NLR 通过 N 端 Toll 样/IL-1 受体（TIR）或非 TIR（卷曲螺旋或 CC）结构域激活植物防御。CC/TIR 结构域的同源二聚体或自缔合特性有助于植物 NLR 自身活性和诱导体内异位细胞死亡。拟南芥 RPS4、L6、SNC1、RPP1 和 Muscadinia rotundifolia RPV1 的高分辨率晶体结构表明，这种相互作用是通过一个或两个独特的界面介导的，即αA 和αE 螺旋组成 AE 界面，而αD 和αE 螺旋则形成 DE 界面。相比之下，植物 NLRs 的 CC 结构域的保守螺旋区域已被确定。NLR 多样化的进化历史表明，成对形式起源于 NLR 单体。植物 TIRs 执行 NAD 水解活性以促进细胞死亡。已经发现植物 NLR 形成了类似于动物炎症小体的大型寡聚复合物。我们还讨论了不同的蛋白质工程方法，包括结构域改组和诱饵修饰，这些方法可以增加植物 NLRs 的效应子识别谱。总之，我们的综述强调了 NLR 或 NLR 对识别毒力因子的结构基础，以设计新型植物免疫受体。
