Understanding the rules of impermeability in Gram negative bacteria

Modern medicine relies on being able to treat and prevent bacterial infection with antibiotics but the global crisis in antimicrobial resistance (AMR) means that these infections are becoming harder to treat. Most antibiotics must get inside bacteria to a certain concentration to kill them. Gram-negative bacteria, such as Salmonella and E. coli, are surrounded by a complex multi-layered cell envelope, which is a highly effective barrier that prevents antibiotics and other toxic molecules from entering the cell. These bacteria also have efflux pumps which export toxic molecules out of the cell. This Gram-negative cell envelope is a major determinant of AMR and remains the major hurdle to both the effective treatment of bacterial infection and the development of new antibiotics.
We have recently discovered that the mechanisms bacteria use to limit antibiotic  accumulation vary dramatically between different conditions. In particular, the relative importance of prevention of antibiotic entry, and pumping antibiotics outside the cell, changes depending on the physiological state of the bacteria and their environmental conditions. However, we still do not fully understand how different infection conditions influence antibiotic accumulation inside bacterial cells, what drives these changes, or how bacteria regulate this process.
This proposal will address these knowledge gaps by taking an interdisciplinary approach integrating expertise in bacterial efflux pumps, membrane biology, single cell analysis, antimicrobial accumulation, gene expression, metabolic changes and mathematics. We will develop new ways to measure how antibiotics get into cells and determine how this changes in different conditions relevant to infection. We will then be able to discover what cellular changes alter the level of antibiotic accumulation and how bacteria control this. Throughout, we will use data from these experiments to build and validate a mathematical model that we can use to...