In-silico identification and characterization of effector proteins in the rice blast pathogen Magnaporthe oryzae

Rice is the primary staple food for over half the world’s population, but its production faces a severe threat from the devastating blast disease caused by the fungal pathogen Magnaporthe oryzae (Syn . Pyricularia oryzae ) . Disease-resistant rice cultivars, a key strategy to combat this issue, often lose their resistance due to the fungal genome’s ability to evade plant immunity through effector proteins. Understanding these effectors is crucial to unravel the mechanism of rice blast diseases. In the reference proteome of M. oryzae , a substantial number of proteins (3777) remain uncharacterized. Our study aimed to identify and characterize novel effector proteins from the rice blast pathogen, M. oryzae , contributing to its pathogenicity. Through systematic analysis using advanced bioinformatics tools, we identified twenty-nine uncharacterized proteins as probable effectors and focused on the one with the highest secretory (secretion score, 0.94/1.0) and pathogenicity-contributing features (ribosyltransferase toxin domain), designated as a probable effector protein (PEP). Remarkably, PEP was characterized as an ADP-ribosylating domain-containing protein, and with catalytically important residues (ARG25, SER77, 130GLU, and 132GLU) matching those in the A chain of ADP-ribosylating enterotoxins. Structural stability analysis using 200 ns dynamics simulation indicated that PEP is a stable protein, exhibiting hallmark features of ADP-ribosylating proteins, as confirmed by the molecular interaction of NAD+ with the catalytic pocket of PEP with distance of 2.13–3.06 Å. This study, for the first time, identified and characterized an effector protein, PEP, in the rice blast fungus M. oryzae , potentially involved in modulating host defence against this destructive fungus. Validation of this in silico identified effector through laboratory and greenhouse experiments is warranted.