Part of the type VI secretion system (T6SS) specialized secretion system, which delivers several virulence factors in both prokaryotic and eukaryotic cells during infection (PubMed:26150500). Forms the spike at the tip of the elongating tube probably formed by hemolysin co-regulated protein/Hcp. Allows the delivery of the TseL antibacterial toxin to target cells where it exerts its toxicity (PubMed:26150500). Acts also directly as an actin-directed toxin that catalyzes the covalent cross-linking of host cytoplasmic monomeric actin. Mediates the cross-link between 'Lys-50' of one monomer and 'Glu-270' of another actin monomer, resulting in formation of highly toxic actin oligomers that cause cell rounding (PubMed:17873062, PubMed:20150509). The toxin can be highly efficient at very low concentrations by acting on formin homology family proteins: toxic actin oligomers bind with high affinity to formins and adversely affect both nucleation and elongation abilities of formins, causing their potent inhibition in both profilin-dependent and independent manners (By similarity). Acts as an acid--amino-acid ligase that transfers the gamma-phosphoryl group of ATP to the 'Glu-270' actin residue, resulting in the formation of an activated acyl phosphate intermediate. This intermediate is further hydrolyzed and the energy of hydrolysis is utilized for the formation of the amide bond between actin subunits (By similarity). Binds 2 Mg(2+) ions per subunit. Can also use Mn(2+) ions instead of Mg(2+). Interacts with protein VC1417. Secreted via the type VI secretion system. Deletion leads to a loss of TseL secretion and in turn loss of its ability to mediate prey cell killing. Belongs to the VgrG protein family.