Toxin secreted by the type VI (T6SS) secretion system that acts on prokaryotic as well as eukaryotic target cells. Interacts with VgrG3; this interaction allows TseL secretion to target cells. Delivered to the target cell by the type VI (T6SS) secretion system in a VgrG3-dependent pathway. Deletion does not abolish killing activity. However, triple mutant lacking tseL, vasX, and vgrG3 fails to kill Escherichia coli.