Identification of substrates and roles in virulence of the Staphylococcus aureus Ess protein secretion system

Staphylococcus aureus is a Gram positive bacterium responsible for a number of illnesses in humans including septicaemia and pneumonia. It is most widely known as a major cause of hospital-acquired infections, and this has been exacerbated by the fact that some strains of S. aureus, such as methicillin-resistant S. aureus (MRSA), are resistant to many antibiotics making it a severe and difficult to treat. Almost all bacteria cause disease by producing toxins that they secrete into the host. Many of these toxins are protein molecules, and the bacterium has specialized machines in the cell membrane that allow the controlled passage of these toxins to the outside. We are working on one of these machines in S. aureus called the Ess system, which is essential for its virulence. 

We aim to understand the range of different proteins secreted by the Ess system and which of these are important for the organism to cause disease. For those toxic proteins we identify we will aim to understand the mechanism by which they promote infection. We would also like to develop a screen that will allow us to look for small molecules that inhibit the activity of the Ess secretion system.