Bacterial toxins and the Rho GTP-binding protein: what microbes teach us about cell regulation.

In the present review activities of two bacterial toxins, Clostridium botulinum exoenzyme C3 and Escherichia coli CNF1, both acting on the GTP-binding protein Rho are analyzed. Proteins belonging to the Rho family regulate the actin cytoskeleton and act as molecular switches in a number of signal transduction pathways. C3 and CNF1 have opposite effects on Rho thus representing useful tools for studies on cell division, cell differentiation and apoptosis.