PilX, a pilus-associated protein essential for bacterial aggregation, is a key to pilus-facilitated attachment of Neisseria meningitidis to human cells
Article first published online: 12 OCT 2004
Volume 55, Issue 1, pages 65–77, January 2005
How to Cite
Hélaine, S., Carbonnelle, E., Prouvensier, L., Beretti, J.-L., Nassif, X. and Pelicic, V. (2005), PilX, a pilus-associated protein essential for bacterial aggregation, is a key to pilus-facilitated attachment of Neisseria meningitidis to human cells. Molecular Microbiology, 55: 65–77. doi: 10.1111/j.1365-2958.2004.04372.x
- Issue published online: 25 NOV 2004
- Article first published online: 12 OCT 2004
- Accepted 19 August, 2004.
The attachment of pathogenic Neisseria species to human cells, in which type IV pili (Tfp) play a key but incompletely defined role, depends on the ability of these bacteria to establish contacts with the target cells but also interbacterial interactions. In an effort to improve our understanding of the molecular mechanisms of N. meningitidis adherence to human cells, we screened a collection of defined mutants for those presenting reduced attachment to a human cell line. Besides underscoring the central role of Tfp in this process, this analysis led to the identification of mutants interrupted in a novel gene termed pilX, that displayed an adherence as impaired as that of a non-piliated mutant but quantitatively and qualitatively unaltered fibres. Moreover, the pilX gene, which encodes a pilin-like protein that copurifies with Tfp fibres, was also found to be essential for bacterial aggregation. We provide here several piece of evidence suggesting that PilX has intrinsic aggregative but no adhesive properties and that the reduced numbers of adherent bacteria seen with a pilX mutant result from the absence of interbacterial interactions. These data extend the current model for Tfp-facilitated adherence of N. meningitidis to human cells by suggesting that the pili lead to an increase in net initial adherence primarily by mediating a cooperation between the bacteria, which is supported by the finding that a major effect on initial adherence could be observed in a wild-type (WT) genetic background after a mechanical removal of the bacterial aggregates.