[SCAN] Investigating the role of cell wall synthetic enzymes in surface protein presentation in Staphylococcus aureus

Title: Investigating the role of cell wall synthetic enzymes in surface protein presentation in Staphylococcus aureus

Speaker: Patrícia Reed

Affiliation: Bacterial Cell Biology- Mariana Gomes de Pinho Lab

Abstract: S. aureus is a clinically important gram-positive pathogen, well known for its acquired resistance to most contemporary antibiotics. It is notable by its prevalence in health care environments and is currently one of the leading causes of hospital- and community-acquired infections. The current crisis caused by antimicrobial resistance demands new strategies to fight infections. One approach is targeting virulence as a means of blocking pathogenicity.
Gram-positive bacteria have a thick layer of peptidoglycan (PG) surrounding the cell, it forms a stress bearing sacculus that prevents lysis of bacteria due to turgor pressure. The integrity of PG is therefore essential for bacterial survival and its synthesis is the target of many important antibiotics. In our lab we have extensively studied the roles of the cell wall synthetic enzymes (PBPs) in the building of the Staphylococcal cell wall, their roles in cell division and antibiotic resistance.
In the first part of this talk I will show how we identified the minimal peptidoglycan synthesis machinery of Staphylococcus aureus, that maintains normal growth and cell morphology in vitro. I will also discuss how the non-essential PG synthesis enzymes are important for survival in more challenging environments such as in the presence of antibiotics or within the host.
S. aureus also decorates its cell surface with a plethora of proteins; many of which are virulence factors. One major group of proteins (LPxTG proteins) are covalently linked to the PG by transpeptidase enzymes known as sortases. Sortase mutants, unable to anchor these proteins to the CW envelope, have been shown to display large defects in virulence. During our studies of cell wall synthesis we uncovered a link between the PG synthetic enzymes and the LPxTG proteins displayed at the cell surface. In the second part of this talk I will discuss these findings and current results from this investigation.