A Dual‐Targeting T6SS DNase Drives Bacterial Antagonism and Eukaryotic Apoptosis via the cGAS‐STING‐TNF Axis

Abstract The Type VI secretion system (T6SS) is a key virulence mechanism utilized by many Gram‐negative bacteria to mediate the microbial competition and host pathogenesis. Despite the identification of diverse T6SS effectors targeting eukaryotic or prokaryotic cells, the trans‐kingdom T6SS effectors that simultaneously target both eukaryotic and prokaryotic cells remain rarely reported. In this study, it is demonstrated that Yersinia pseudotuberculosis ( Yptb ) T6SS secretes a DNase effector, TkeA, which induces apoptosis in host cells. The translocation of TkeA into host cells causes nuclear DNA damage. This, in turn, activates the DNA‐sensing cyclic GMP‐AMP synthase (cGAS)/stimulator of interferon genes (STING) pathway. The activation of the cGAS‐STING pathway by TkeA subsequently triggers apoptosis in host cells via extrinsic pathways, with tumor necrosis factor (TNF) signaling playing a critical role. Additionally, TkeA enhances bacterial competition by targeting rival bacteria, thereby promoting host colonization. These findings reveal that the transkingdom T6SS effector TkeA executes a “one weapon, two battlefields” strategy, acting as a trans‐kingdom effector that enhances interbacterial competition while inducing apoptosis in host cells through the activation of the cGAS‐STING‐TNF axis. This highlights a previously unrecognized dimension of bacterial virulence strategies and expands the understanding of host‐pathogen interactions involving T6SS effectors.