Actin organizer takes pathogens for a ride

Enteropathogenic E. coli causes a dramatic actin reorganization in intestinal epithelia, erecting intracellular pedestals on the host cells beneath the attached bacteria. On page 407, Campellone et al. reduce this complex phenomenon to twelve amino acids, showing that clustering a small domain of the bacterial Tir protein, which is translocated to the host cell, is sufficient to induce actin rearrangement. The results highlight an interesting evolutionary convergence, and provide a simple model system for studying actin assembly.

After discovering that Tir is the only E. coli component required for pedestal formation, the authors further whittled the system down to the C-terminal cytoplasmic domain of Tir. Clustering this domain at the plasma membrane causes its phosphorylation, allowing it to bind to the host protein Nck. Nck binding leads to the recruitment of N-WASP...