High-throughput comparative and functional genomic analysis of type IV pilus (Tfp) localised adhesins in the opportunistic human pathogen Streptococcc

Tfp are key virulence factors in many human bacterial pathogens thta cause millions of
deaths each year worldwide. A better understanding of Tfp biology is highly desirable as it
will be crucial for developing new prevention and therapy methods. Tfp are key for host
colonisation as they mediate attachment fo bacteria to host cells and surfaces.

Unfortunately, the molecular mechanisms of Tfp-mediated adhesion are poorly
understood, which hinders the design of new treatments. This project stems from on our
recent discovery of subunits that are likely to play a direct role in adhesion in the Tfp of
the opportunistic human pathogen S. sanguinis, which causes infective endocarditis a lifethreatening
condition. During this project, we will use a state-of-the-art multi-disciplinary
approach combining high-throughput genomics, molecular genetics, protein biochemistry
and structural biology to characterise in detail these two newly discovered adhesins named
PilB and PilC.

In brief, since a preliminary comparative genomic analysis on the few
publicly available S. sanguinis genomes revealed some sequence variability in PilB and
PilC, which might have important functional consequences, a large collection of clinical
isolates of S. sanguinis will be sequenced to determine the degree of variability of these
two adhesins and see if there is a correlation with clinical symptoms. Then, using
molecular genetics, the functional consequences of these sequence variations will be
analysed in vivo. Finally, representative variant proteins will be purified, analysed
functionally in vitro and submitted to structural analysis. This is expected to give an
uprecedented understanding of Tfp-mediated adhesion and could be the first step towards
the design of new drugs interfering with Tfp-mediated colonisation in important human
bacterial pathogens.