Pili of pathogenic Neisseria are major virulence factors associated with adhesion,
twitching motility, autoaggregation, and DNA transformation. Pili of N. meningitidis
are subject to several different post-translational modifications. Among these pilin
modifications, the presence of phosphorylcholine (ChoP) and a glycan on the pilin
protein are phase-variable (subject to high frequency, reversible on/off switching of
expression). In this study we report the location of two ChoP modifications on the Cterminus
of N. meningitidis pilin. We show that the surface accessibility of ChoP on
pili is affected by phase variable changes to the structure of the pilin-linked glycan.
We identify for the first time that the platelet activating factor receptor (PAFr) is a
key, early event receptor for meningococcal adherence to human bronchial epithelial
cells and tissue, and that synergy between the pilin-linked glycan and ChoP posttranslational
modifications is required for pili to optimally engage PAFr to mediate
adherence to human airway cells.