Required for full activity and modification of the LtxA leukotoxin. Involved in fatty acid modification of the protoxin at two internal lysine residues, thereby converting it to the active toxin. a fatty acyl-[ACP] + L-lysyl-[protein] = H(+) + holo-[ACP] + N(6)-(fatty acyl)-L-lysyl-[protein] Levels of toxin expression vary greatly among strains. Highly leukotoxic strains (JP2-type strains) produce more LtxA protein and ltx mRNA than minimally leukotoxic strains (652-type strains). Variations are probably due to different types of promoters. Mutants can express and secrete the LtxA leukotoxin, but LtxA lacks both leukotoxic and erythrolytic activities, and is unable to cause a change in intracellular calcium levels in host cells. Belongs to the RTX toxin acyltransferase family.