Contact-independent killing mediated by a T6SS effector with intrinsic cell-entry properties

Abstract Bacterial type VI secretion systems (T6SSs) inject toxic effectors into adjacent eukaryotic and prokaryotic cells. It is generally thought that this process requires physical contact between the two Here, we provide evidence of contact-independent killing by a T6SS-secreted effector. We show pathogen Yersinia pseudotuberculosis uses T6SS (T6SS-3) to secrete nuclease effector kills other bacteria in vitro facilitates gut colonization mice. The (Tce1) small protein acts as Ca 2+ - Mg -dependent DNase, its toxicity inhibited cognate immunity protein, Tci1. As expected, T6SS-3 mediates canonical, contact-dependent directly injecting Tce1 In addition, also neighboring cells absence cell-to-cell contact, secreting extracellular milieu. Efficient entry target proteins OmpF BtuB outer membrane discovery contact-independent, long-range toxin delivery provides new perspective for understanding physiological roles competition. However, mechanisms mediating uptake remain unclear.