Type IV pili—a numbers game

Type IV pili are long polymers located on the surface of a wide variety of bacterial cells, including the pathogen Neisseria meningitidis . They are responsible for a diverse range of functions, including adhesion, motility and natural transformation. In this issue of The EMBO Journal , Imhaus and Duménil show that two minor pilins, PilX and PilV, exert some of their effects by changing mean surface pilus number and that this modulates different pilus‐dependent functions.