Type IV pilus: one architectural problem, many structural solutions.

Type IV pili are long appendages found at the surface of many bacteria, composed of an oligomerized pilin protein and involved in processes such as adherence, motility and DNA transfer. In this issue of Structure, Piepenbrink and colleagues report the first structure a major pilin from a Gram-positive bacterium, revealing an unprecedented stabilization mechanism that may have implications for pilus evolution.