Versatile type III effector mechanisms can disrupt target-cell functions

• By injecting proteins called effectors into host cells, bacterial pathogens can alter crucial biochemical signaling pathways in those targeted cells. • The effectors from different bacteria may do very different things in host cells, mimicking or usurping eukaryotic activities in a variety of ways. • Bacteria apparently reshuffled the domains of some eukaryotic genes to produce novel virulence factors. • Instead of hydrolyzing target proteins in host cells, the bacterial effector YopJ modifies proteins by acetylating serine and threonine residues on the activation loop of certain kinases.