Moreira, R.; Giurgiu, C.; Rahman, I. R.; Patterson, M.; Huber, S. T.; Yang, Y.; Jeanne Dit Fouque, K.; Fernandez-Lima, F.; Liu, G.; Guo, R.; Kelich, P.; Wen, P.-C.; Tajkhorshid, E.; Johnson, A. G.; van der Donk, W. A.

The enterococcal cytolysin is a two-component lanthipeptide natural product that co-operatively kills mammalian cells and bacteria. It is a virulence factor in typically commensal strains of gut-dwelling Enterococcus faecalis and causes a fatal form of alcoholic hepatitis. Despite its clinical significance, little is known about the mechanism of action. We present here the molecular details of cytolysin's remarkable bioactivity. A high-resolution cryo-electron microscopy structure revealed highly ordered tubular assemblies comprising the two subunits. We further demonstrate these structures disrupt the membranes of eukaryotic and bacterial cells. These results provide the first high-resolution structure of two distinct lanthipeptides interacting with one another and offer an explanation for the unique bioactivity of the cytolysin toxin.