Type four pilus: RNA-mediated antigenic variation and repression of assembly

Many bacterial pathogens express Type four pili (Tfp) on their surfaces, exerting diverse functions such as twitching motility and DNA uptake.

The Neisseria meningitidis (meningococcus) Tfp is subject to high-frequency antigenic variation (AV), enabling the bacterium to modulate its pilin sequence, facilitating immune evasion. Despite playing key role in virulence, regulation governing Tfp AV and functions of each variant remains unknown.

In Aim 1, we will use the unique molecular identifier-linked consensus (UMIC-seq) to determine meningococcal Tfp AV in different growth conditions, as well as to characterise the function of each pilus variant. Our preliminary result suggests that novel regulatory RNA:DNA interactions could influence Tfp AV.

In Aim 2, we will investigate the effect of AS-RNA molecules with a 2´-O-methyl modified RNA backbone with complementary sequence to one of the Tfp genes (pilF), coupled to unique uptake sequence, in modulating Tfp assembly and virulence.

In Aim 3, we will establish a microfluidic blood vessel infection model to investigate meningococcal pathogenesis in a more “native” environment.

Through this model, the observation of meningococcal pilin AV (Aim 1), the efficiency of the AS-RNA molecules on Tfp assembly (Aim 2), disease progression and host inflammation will be performed.

Overall, this proposal is ground breaking and could lay the foundation for the more research into Tfp, AV and RNA-mediated gene regulation in other pathogens.