Nematotoxicity of Marasmius oreades Agglutinin (MOA) depends on glycolipid binding and cysteine protease activity

Therese Wohlschlager, Alex Butschi, Katrin Zurfluh, Sibylle C. Vonesch, Ulrich Auf Dem Keller, Peter Gehrig, Silvia Bleuler-Martinez, Michael O. Hengartner, Markus Aebi, Markus Künzler*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review


Fruiting body lectins have been proposed to act as effector proteins in the defense of fungi against parasites and predators. The Marasmius oreades agglutinin (MOA) is a Galα1,3Gal/GalNAc-specific lectin from the fairy ring mushroom that consists of an N-terminal ricin B-type lectin domain and a C-terminal dimerization domain. The latter domain shows structural similarity to catalytically active proteins, suggesting that, in addition to its carbohydrate-binding activity, MOA has an enzymatic function. Here, we demonstrate toxicity of MOA toward the model nematode Caenorhabditis elegans. This toxicity depends on binding of MOA to glycosphingolipids of the worm via its lectin domain. We show further that MOA has cysteine protease activity and demonstrate a critical role of this catalytic function in MOA-mediated nematotoxicity. The proteolytic activity of MOA was dependent on high Ca 2+ concentrations and favored by slightly alkaline pH, suggesting that these conditions trigger activation of the toxin at the target location. Our results suggest that MOA is a fungal toxin with intriguing similarities to bacterial binary toxins and has a protective function against fungivorous soil nematodes.

Original languageEnglish
JournalJournal of Biological Chemistry
Issue number35
Pages (from-to)30337-30343
Publication statusPublished - 2011
Externally publishedYes

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