A fungal substrate mimicking molecule suppresses plant immunity via an inter-kingdom conserved motif
A fungal substrate mimicking molecule suppresses plant immunity via an inter-kingdom conserved motif
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DOI：
10.1038/s41467-019-09472-8
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发表时间：
2019-04
影响因子：
16.6
通讯作者：
Johana C. Misas Villamil;André N. Mueller;Fatih Demir;Ute Meyer;B. Ökmen;Jan Schulze Hüynck;Marlen Breuer;Helen Dauben;J. Win;Pitter F. Huesgen;G. Doehlemann
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作者：
Johana C. Misas Villamil;André N. Mueller;Fatih Demir;Ute Meyer;B. Ökmen;Jan Schulze Hüynck;Marlen Breuer;Helen Dauben;J. Win;Pitter F. Huesgen;G. Doehlemann
玉米黑粉病是一种引起玉米黑粉病的生物营养真菌。分泌的效应蛋白Pit2是木瓜蛋白酶样半胱氨酸蛋白酶(PLCP)的抑制物，对毒力至关重要。PIT2的抑制作用依赖于一个保守的14个氨基酸基序(PID14)。在这里，我们展示了合成的PID14肽比全长的PIT2效应器更有效地发挥PLCP抑制剂的作用。质谱仪显示玉米PLCP对Pit2的处理，它从PID14序列中释放出一个抑制核心基序。突变分析表明，两个保守残基是Pit2功能所必需的。我们认为Pit2效应器作为底物模拟分子发挥作用：Pit2是质外体PLCP的合适底物，它的加工释放嵌入的抑制肽，进而阻止PLCP调节宿主免疫。值得注意的是，PID14核心基序存在于几种植物相关的真菌和细菌中，表明存在一种保守的微生物蛋白水解酶抑制因子(CMIP)。
Ustilago maydisis a biotrophic fungus causing corn smut disease in maize. The secreted effector protein Pit2 is an inhibitor of papain-like cysteine proteases (PLCPs) essential for virulence. Pit2 inhibitory function relies on a conserved 14 amino acids motif (PID14). Here we show that synthetic PID14 peptides act more efficiently as PLCP inhibitors than the full-length Pit2 effector. Mass spectrometry shows processing of Pit2 by maize PLCPs, which releases an inhibitory core motif from the PID14 sequence. Mutational analysis demonstrates that two conserved residues are essential for Pit2 function. We propose that the Pit2 effector functions as a substrate mimicking molecule: Pit2 is a suitable substrate for apoplastic PLCPs and its processing releases the embedded inhibitor peptide, which in turn blocks PLCPs to modulate host immunity. Remarkably, the PID14 core motif is present in several plant associated fungi and bacteria, indicating the existence of a conserved microbial inhibitor of proteases (cMIP).