Hierarchical, non-additive MARTX effector interplay rewires host transcription to drive Vibrio vulnificus invasion and lethal sepsis

Multifunctional-autoprocessing repeats-in-toxin (MARTX) toxins deliver multiple effectors into host cells, yet how distinct effector combinations integrate to shape virulence remains poorly defined. Here, we systematically dissect effector interplay in the highly virulent pathogen Vibrio vulnificus. In the M-type MARTX toxin strain MO6-24/O, which delivers four effectors, we generated catalytically-inactivating point mutations in all combinations in situ. We found that effector composition influences virulence potential, revealing both virulence and anti-virulence factors. Integrated transcriptomics revealed that coordinated effector activity governs the magnitude and coherence of host response. Two functional effector modules define a regulatory–metabolic axis and a silencing–execution axis, each partially contributing to virulence. When combined into the holotoxin, these modules reprogram host transcription toward a highly activated state, supporting a model in which virulence emerges from non-additive effector crosstalk that rewires host transcriptional landscapes.