研究人员表示，植物细胞内的核苷酸结合富含亮氨酸重复（NLR）受体通过其N端的Toll/白介素-1受体（TIR）结构域感知病原效应分子并启动免疫信号。
不同界的TIR结构域具有NAD酶活性，能够生成磷核糖基腺苷单磷酸/二磷酸（pRib-AMP/ADP）或环状ADPR（cADPR）异构体。类脂酶样蛋白EDS1和PAD4将免疫信号从传感器TIR-NLR传递到一个名为ADR1的辅助NLR，后者执行免疫功能。
研究人员报告了拟南芥EDS1-PAD4-ADR1（EPA）异三聚体的结构和功能，该三聚体与由植物或细菌TIR信号激活的pRib-AMP/ADP复合物结合。2’cADPR可以水解为pRib-AMP，从而激活EPA信号。产生2’cADPR的细菌TIR结构域也能激活EPA功能。这些研究结果表明，2’cADPR可能是具有不稳定信号分子pRib-AMP的储存形式。
附：英文原文
Title: Activation of a helper NLR by plant and bacterial TIR immune signaling
Author: Hua Yu, Weiying Xu, Sisi Chen, Xiaoxian Wu, Weiwei Rao, Xiaoxiao Liu, Xiaoyan Xu, Jingqi Chen, Marc T. Nishimura, Yu Zhang, Li Wan
Issue&Volume: 2024-11-07
Abstract: Plant intracellular nucleotide-binding leucine-rich repeat (NLR) receptors with an N-terminal Toll/interleukin-1 receptor (TIR) domain sense pathogen effectors to initiate immune signaling. TIR domains across different kingdoms possess NADase activities and can produce phosphoribosyl adenosine monophosphate/diphosphate (pRib-AMP/ADP) or cyclic ADPR (cADPR) isomers. Lipase-like proteins, EDS1 and PAD4, transduce immune signals from sensor TIR-NLRs to a helper NLR called ADR1, which executes immune function. We report the structure and function of Arabidopsis EDS1-PAD4-ADR1 (EPA) heterotrimer in complex with pRib-AMP/ADP activated by plant or bacterial TIR signaling. 2’cADPR can be hydrolyzed into pRib-AMP and thus activates EPA signaling. Bacterial TIR domains producing 2’cADPR also activate EPA function. Our findings suggest that 2’cADPR may be the storage form of the unstable signaling molecule pRib-AMP.
DOI: adr3150
Source: https://www.science.org/doi/10.1126/science.adr3150