Toxic Properties of Urease

Plant ureases have long been known for their ureolytic activities, dependent on a Ni metallocenter active site. We report here on more recently discovered novel toxic properties of ureases—properties independent of enzyme activity. Plant ureases have potent toxicity against insects that are not affected by Bt toxins. Entomotoxicity relies on an internal peptide released by insect digestive enzymes. Plant ureases are fungitoxic—in the absence of ureolytic activity—a property shared with some microbial ureases. We have found that both plant and microbial ureases also induce secretion in animal cells (and thus might be defense and pathogen factors, respectively). We suggest that in the soil, bacterial urease‐induced secretion by plant roots may play a role in rhizosphere relationships. While ureases of plant, fungi, and bacteria align with greater than 50% amino acid identity, toxicity and signaling may be due to more divergent domains, such as that for the insecticidal sub‐peptide. These domains are potential targets for manipulation to improve plant defense against herbivores and pathogens.