Virulence-associated N-epsilon-fatty acyltransferase that mediates lysine-stearoylation of host Rho GTPase proteins, thereby disrupting the host actin cytoskeleton (PubMed:30061757). Required at the post-invasion stage of Shigella pathogenicity (PubMed:12753186). L-lysyl-/S-(2E,6E,10E)-geranylgeranyl-L-cysteinyl-[protein] + octadecanoyl-CoA = CoA + H(+) + N(6)-octadecanoyl-L-lysyl-/S-(2E,6E,10E)-geranylgeranyl-L-cysteinyl-[protein] Secreted via type III secretion system (PubMed:12753186). Requires IpgA as a chaperone for its stability and secretion (PubMed:12753186). Localizes on Shigella-containing host vacuoles and modifies its substrates there (PubMed:30061757). The icsB gene can be read-through into the ipgA gene to create a translational fusion protein. The biological significance of this process is unclear. Belongs to the BopA/IcsB family.