Background
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 lectin from the fairy ring mushroom with specificity for Galα1-3Gal containing carbohydrates. This lectin is composed of an N-terminal carbohydrate-binding domain and a C-terminal dimerization domain. The dimerization domain of MOA shows in addition calcium-dependent cysteine protease activity, similar to the calpain family.
Conclusion
Our results suggest a possible toxic mechanism of MOA, which consists of disturbing the cell adhesion and the cell viability. General significance: After being ingested by a predator, MOA might exert a protective role by diminishing host cell integrity.
Methods
Cell detachment assay, cell viability assay, immunofluorescence, live cell imaging and Western blot using MDCKII cell line.
Results
In this study, we demonstrate in MDCKII cells that after internalization, MOA protease activity induces profound physiological cellular responses, like cytoskeleton rearrangement, cell detachment and cell death. These changes are preceded by a decrease in FAK phosphorylation and an internalization and degradation of β1-integrin, consistent with a disruption of integrin-dependent cell adhesion signaling. Once internalized, MOA accumulates in late endosomal compartments.
Significance
After being ingested by a predator, MOA might exert a protective role by diminishing host cell integrity.