Imaging Organization in the Escherichia Coli Outer Membrane

Antibiotic resistance in bacteria is on the rise for all classes of antibiotic. In the case of pathogenic Gram-negative bacteria, many are intrinsically resistant to some classes of antibiotics due to the outer-membrane (OM) acting as a diffusion barrier for drug molecules. Hence understanding how the OM is built and maintained offers new routes for combatting antimicrobial resistance. The OM is asymmetric, with an outer leaflet of lipopolysaccharides (LPS) and an inner leaflet of phospholipids. The predominant proteins within this asymmetric bilayer are β-barrel outer membrane proteins (OMPs). While a great deal is known about the biogenesis of OMPs and LPS and how they are deposited on the surface of Gram-negative bacteria, surprisingly little is known about how these molecules are organised relative to each other in a live bacterium. Using OMP-specific fluorescent probes, we recently discovered that OMPs are organised into large, supramolecular assemblies (OMP islands) the formation of which underpins the turnover of OMPs in bacteria. In the work to be presented, we combine diffraction limited fluorescence and super-resolution microscopy methods with specific labelling of OMPs and LPS to investigate their relative organisation in live bacteria and how these change during cell division and in response to environmental stress factors.