Structural and functional insights into the delivery of a bacterial Rhs pore-forming toxin to the membrane
Amaia González‐Magaña, Igor Tascón, Jon Altuna-Alvarez, María Queralt-Martín, Jake Colautti, Carmen Velázquez, Maialen Zabala-Zearreta, Jéssica Rojas-Palomino, Marité Cárdenas, Antonio Alcaraz, John C. Whitney, Iban Ubarretxena‐Belandia, D. Albesa-Jové
Abstract
Bacterial competition is a significant driver of toxin polymorphism, which allows continual compensatory evolution between toxins and the resistance developed to overcome their activity. Bacterial Rearrangement hot spot (Rhs) proteins represent a widespread example of toxin polymorphism. Here, we present the 2.45 Å cryo-electron microscopy structure of Tse5, an Rhs protein central to Pseudomonas aeruginosa type VI secretion system-mediated bacterial competition. This structural insight, coupled with an extensive array of biophysical and genetic investigations, unravels the multifaceted functional mechanisms of Tse5. The data suggest that interfacial Tse5-membrane binding delivers its encapsulated pore-forming toxin fragment to the target bacterial membrane, where it assembles pores that cause cell depolarisation and, ultimately, bacterial death.