Transfer of toxins in Staphylococcus aureus

Bacteria can exchange parts of their genome, known as the mobilome.

The purpose of this project is to investigate how pathogenicity islands in Staphylococcus aureus, called SaPIs, are mobilized between bacterial cells, and to characterize genes with unknown functions that are encoded by SaPIs.SaPIs encode toxins and virulent genes and are integrated into the Staphylococcal genome, representing an essential part of the mobilome.

Upon induction, SaPIs replicate and transfer to new recipient staphylococcal cells extremely efficiently.

The SaPI’s medical significance lies in the fact that they can convert a harmless S. aureus into a deadly and virulent strain in a single event by transferring to a new cell. I plan to study how the induction process occurs mechanistically. I will use cryoEM to understand how the induction is achieved.

Additionally, I will characterize genes with unknown functions in SaPIs. I present here a proof of concept that several genes are defense systems against bacteriophages.

I will use my expertise in phage biology to identify which phage protein is targeted by the defense system and to characterize mechanistically how the defense system works.This proposal will serve as the basis for designing new strategies in the future to prevent the spread of virulent and antimicrobial genes in S. aureus, one of the most serious infective agents worldwide.

Characterizing new phage defense systems has the potential to find new biotechnology tools yet unthinkable.