Grant: Project Grant

Ensuring the mechanical strength of their cell walls is essential to the viability of bacteria. This strength to the wall is conferred by a continuous (macro)molecule unique to bacteria called peptidoglycan which completely encases the cell. Given the importance of the peptidoglycan layer for bacterial survival, it is not surprising that higher eukaryotes have exploited this "Achilles heel" to combat infections. However, pathogenic bacteria have adapted to this response by chemically modifying their peptidoglycan thereby preventing its disruption. One such modification is O-acetylation. In the absence of this modification, pathogenic bacteria become extremely susceptible to host innate immune factors, particularly to the peptidoglycan-lytic enzyme called lysozyme. Additionally, this O-acetylation serves to control peptidoglycan metabolism within a bacterium by blocking the function of endogenous lytic enzymes essential for cell growth and division. Consequently, bacteria require the activity of an enzyme (named Ape) to remove blocking acetyl groups when required to permit continued PG metabolism. Inhibition of Ape prevents further growth of bacteria that require the enzyme (eg., Neisseria gonorrhoeae) and its activity is essential for survival of Neisseria meningitidis in animal models. The research plan that we propose builds on our findings to date on the specificity and structure-function relationships of the enzymes involved in both adding and removing this O-acetylation. Experiments involving biochemical, kinetic, and structural characterisations are designed to better inform the search/development of strong inhibitors of these enzymes that my represent leads to new antibacterials.