Ribosome-inactivating proteins from edible plants: Isolation, characterization and possible biotechnological applications

Here, we report the known ribosome-inactivating proteins (RIPs) currently isolated and characterized from edible plants. These ribosome-targeting toxins are N-β-glycosylases that depurinate ribosomes and inhibit protein biosynthesis. RIPs found in edible plants cover 23 species, while protein synthesis inhibitors cover nine species. Most of them are found in Caryophyllales, Cucurbitales, Poales, Fabales, Asparagales, Santalales, and Apiales orders. Moreover, few RIP genes or transcripts have been heterologously expressed and N-β-glycosylase activity was characterized. RIPs possess antibacterial, antiviral, antifungal, and insecticidal properties, likely associated with plant defense. This is consistent with their increased expression during biotic and abiotic plant stresses. Moreover, transgenic plants in which RIPs are overexpressed exhibit enhanced resistance to pathogen attacks. The broad spectrum of RIP activities could be exploited in agriculture to engineer species of agronomic interest, overcoming the preconception about transgenic plants, being these enzymes physiologically present in edible plants, often consumed as raw food.