(312f) Engineering of a Polygalacturonase-Inhibiting Protein As a Pest Control Agent

Fungal pathogens cause extensive plant disease in the agricultural industry, resulting in historical crop failures and diminished food security. Though effective fungicides have been developed, their negative impacts on the environment and animal health have been well documented. A more sustainable and health conscientious method of controlling fungi is desired. Plants produce a group of leucine-rich repeat (LRR) proteins, polygalacturonic inhibiting proteins (PGIPs), to inhibit the pectin-depolymerizing activity of endopolygalacturonases (PGs), one type of enzyme secreted by pathogens that compromise the cell wall and leave the plant susceptible to disease. Here, the inhibitory activity of the best characterized PGIP, PGIP2 from Phaseolus vulgaris, against PGs from Aspergillus niger (AnPG2) and Botrytis cinerea (BcPG1, BcPG2) was reconstituted through a yeast two hybrid (Y2H) system, which was utilized to estimate the activity of various PvPGIP2 truncations and mutants, and establish the sequence-function correlation. We found that truncating PvPGIP2 down to 1/3 of the size still retain the same level of inhibitory activity as the full length PvPGIP2, which may simplify the future engineering efforts for bioproduction and protein evolution. Additionally, the inhibitory activities of PvPGIP2 and mutants on the growth of A. niger and B. cinerea were examined and confirmed on the pectin agar. This work highlights the potential of using plant-derived PGIPs as an exogenously applied fungal control agent both to plants and postharvest crops while minimally impacting the environment and human health.