Extracellular proteolytic cascade in tomato activates immune protease Rcr3
Extracellular proteolytic cascade in tomato activates immune protease Rcr3
复制标题
DOI：
10.1073/pnas.1921101117
复制
发表时间：
2020-07-21
影响因子：
11.1
通讯作者：
van der Hoorn, Renier A. L.
中科院分区：
文献类型：
--
作者：
Paulus, Judith K.;Kourelis, Jiorgos;van der Hoorn, Renier A. L.
蛋白水解级联调节动物的免疫和发育，但这些级联在植物中尚未报道。在这里，我们报告，番茄的胞外免疫蛋白酶Rcr 3被激活的P69 B和其他枯草杆菌酶（SBT），揭示了一个蛋白水解级联调节茄科植物的胞外免疫。Rcr 3是番茄分泌的木瓜样Cys蛋白酶（PLCP），其在针对晚疫病（Phytophthora infestans）的基础抗性和针对真菌病原体黄枝孢（Cladosporium fulvum）的基因对基因抗性中发挥作用。褐钉孢（Passalora fulva）。尽管Rcr 3样蛋白酶可以在低pH下激活自身的流行模型，但我们发现催化失活的proRcr 3突变体前体仍然被加工成成熟的mRcr 3同种型。ProRcr 3由茄科植物中分泌的P69 B和其他Asp-selective SBT加工，通过SBT冗余提供强大的免疫力。致病疫霉的质外体效应因子EPI 1可以通过抑制SBT来阻断Rcr 3的活化，这表明该效应因子通过阻止Rcr 3（-样）免疫蛋白酶的活化而间接促进毒力。本氏烟草中Rcr 3的激活需要来自不同亚科的SBT，这表明胞外蛋白水解级联在茄科植物中已经收敛地进化，或者在植物王国中非常古老。在茄科植物中的Rcr 3样蛋白酶的切割区域中的Asp残基的频繁发生表明SBT对免疫蛋白酶的激活是一种一般机制，阐明了提供稳健的质外体免疫的蛋白水解级联。
Proteolytic cascades regulate immunity and development in animals, but these cascades in plants have not yet been reported. Here we report that the extracellular immune protease Rcr3 of tomato is activated by P69B and other subtilases (SBTs), revealing a proteolytic cascade regulating extracellular immunity in solanaceous plants. Rcr3 is a secreted papain-like Cys protease (PLCP) of tomato that acts both in basal resistance against late blight disease (Phytophthora infestans) and in gene-for-gene resistance against the fungal pathogen Cladosporium fulvum (syn. Passalora fulva). Despite the prevalent model that Rcr3-like proteases can activate themselves at low pH, we found that catalytically inactive proRcr3 mutant precursors are still processed into mature mRcr3 isoforms. ProRcr3 is processed by secreted P69B and other Asp-selective SBTs in solanaceous plants, providing robust immunity through SBT redundancy. The apoplastic effector EPI1 of P. infestans can block Rcr3 activation by inhibiting SBTs, suggesting that this effector promotes virulence indirectly by preventing the activation of Rcr3(-like) immune proteases. Rcr3 activation in Nicotiana benthamiana requires a SBT from a different subfamily, indicating that extracellular proteolytic cascades have evolved convergently in solanaceous plants or are very ancient in the plant kingdom. The frequent incidence of Asp residues in the cleavage region of Rcr3-like proteases in solanaceous plants indicates that activation of immune proteases by SBTs is a general mechanism, illuminating a proteolytic cascade that provides robust apoplastic immunity.