Cuts Both Ways: Proteases Modulate Virulence of Enterohemorrhagic Escherichia coli

Enterohemorrhagic Escherichia coli (EHEC) is a major cause of foodborne gastrointestinal illness. EHEC uses a specialized type III secretion system (T3SS) to form attaching and effacing lesions in the colonic epithelium and outcompete commensal gut microbiota to cause disease. A recent report in mBio (E. A. Cameron, M. M. Curtis, A. Kumar, G. M. Dunny, et al., mBio 9:e02204-18, 2018, https://doi.org/10.1128/mBio.02204-18) describes a new role for gut commensals in potentiating disease caused by EHEC. Proteases produced by EHEC and the prevalent human commensal Bacteroides thetaiotaomicron cleave proteins in the EHEC T3SS translocon that modulate T3SS function. B. thetaiotaomicron protease activity promotes translocation of bacterial effectors required for lesion formation. These results describe a new role for the microbiota in gastrointestinal disease that could uncover future treatments to prevent the spread of gastroenteritis.