PilX is a protein from Neisseria meningitidis which is crucial for the formation of bacterial aggregates and adhesion to human cells [1]. The structure of PilX is similar to all pilins as it has the common alpha/beta roll fold. PilX subunits have surface-exposed motifs which are thought to stabilise bacterial aggregates against pilus retraction. It also illustrates how a minor pilus component can modulate the virulence properties of pili which have a simple composition and structure [1].

1: 3D structure/function analysis of PilX reveals how minor pilins can modulate the virulence properties of type IV pili. Helaine S, Dyer DH, Nassif X, Pelicic V, Forest KT; Proc Natl Acad Sci U S A. 2007;104:15888-15893. PMID:17893339