Marasmius oreades agglutinin (MOA) is a chimerolectin with proteolytic activity

► Marasmius oreades agglutinin (MOA) is a calcium-dependent cysteine protease. ► Cys215 is the catalytic nucleophile in the putative C215-H257-E274 catalytic triad. ► Inhibition of enzymatic activity by papain-like cysteine protease (PCLP) inhibitors. ► However, MOA does not fit the common description of PCLPs. ► Discussion of the functional role of MOA for mushroom defense against invaders.