Tayyrov Annageldi, Wei Chunyue, Fetz Céline, Goryachkin Aleksandr, Schächle Philipp, Nyström Laura, Künzler Markus
Department of Biology, Institute of Microbiology, ETH Zürich, Zurich, Switzerland.
Department of Health Sciences and Technology, Institute of Food, Nutrition and Health, ETH Zürich, Zurich, Switzerland.
Front Fungal Biol. 2021 Jul 1;2:696972. doi: 10.3389/ffunb.2021.696972. eCollection 2021.
Fungi are an attractive food source for predators such as fungivorous nematodes. Several fungal defense proteins and their protective mechanisms against nematodes have been described. Many of these proteins are lectins which are stored in the cytoplasm of the fungal cells and bind to specific glycan epitopes in the digestive tract of the nematode upon ingestion. Here, we studied two novel nematotoxic proteins with lipase domains from the model mushroom . These cytoplasmically localized proteins were found to be induced in the vegetative mycelium of upon challenge with fungivorous nematode . The proteins showed nematotoxicity when heterologously expressed in and fed to several bacterivorous nematodes. Site-specific mutagenesis of predicted catalytic residues eliminated the lipase activity of the proteins and significantly reduced their nematotoxicity, indicating the importance of the lipase activity for the nematotoxicity of these proteins. Our results suggest that cytoplasmic lipases constitute a novel class of fungal defense proteins against predatory nematodes. These findings improve our understanding of fungal defense mechanisms against predators and may find applications in the control of parasitic nematodes in agriculture and medicine.
真菌是诸如食真菌线虫等捕食者极具吸引力的食物来源。几种真菌防御蛋白及其针对线虫的保护机制已被描述。这些蛋白中的许多是凝集素，它们存储在真菌细胞的细胞质中，并在被摄入后与线虫消化道中的特定聚糖表位结合。在此，我们研究了来自模式蘑菇的两种具有脂肪酶结构域的新型杀线虫蛋白。这些定位于细胞质的蛋白被发现是在受到食真菌线虫攻击后，在 的营养菌丝体中被诱导产生的。当这些蛋白在 中异源表达并喂食给几种食细菌线虫时，它们表现出杀线虫毒性。对预测的催化残基进行位点特异性诱变消除了这些蛋白的 脂肪酶活性，并显著降低了它们的杀线虫毒性，这表明脂肪酶活性对这些蛋白的杀线虫毒性很重要。我们的结果表明，细胞质脂肪酶构成了一类新型的针对捕食性线虫的真菌防御蛋白。这些发现增进了我们对真菌针对捕食者的防御机制的理解，并可能在农业和医学中寄生线虫的控制方面找到应用。
