Targeting of the actin cytoskeleton by insecticidal toxins from Photorhabdus luminescens.

Photorhabdus luminescens produces several types of protein toxins, which are essential for participation in a trilateral symbiosis with nematodes and insects. The nematodes, carrying the bacteria, invade insect larvae and release the bacteria, which kill the insects with their toxins. Recently, the molecular mechanisms of the toxin complexes PTC3 and PTC5 have been elucidated. The biologically active components of the toxin complexes are ADP-ribosyltransferases, which modify actin and Rho GTPases, respectively. The actions of the toxins are described and compared with other bacterial protein toxins acting on the cytoskeleton.