Using <i>Caenorhabditis elegans</i> as an infection host model for <i>Vibrio cholerae</i> predator interactions, we discovered a bacterial cytotoxin, MakA, whose function as a virulence factor relies on secretion via the flagellum channel in a proton motive force-dependent manner. The MakA protein is expressed from the polycistronic <i>makDCBA</i> (<i>m</i>otility-<i>a</i>ssociated <i>k</i>illing ...