Model Lipid Bilayers as Platforms for Replicating Bacterial Membranes: A Study of Dynamics and Structural Heterogeneity.

The remarkable complexity of bacterial cell membranes, combined with their diverse chemical composition and constantly changing internal physicochemical parameters, makes them exceptionally challenging to study in vivo. With many novel antibiotics targeting the bacterial cell envelope, considerable effort is now focused on the development of model membrane analogues that allow rapid initial screening of potential antimicrobial candidates. In this study, we successfully developed models based on lipid bilayers that mimic the lipid membrane of Gram-positive bacteria and the inner cell membrane of Gram-negative bacteria. These models incorporate varying levels of complexity in lipid composition and structural organization. Using models composed of DMoPC, DOPG, or DOPE and POPE:POPG binary lipid mixtures, we determined the impact of lipid composition on membrane dynamical properties and structural organization. To this end, we employed fluorescence microscopy and fluorescence recovery after photobleaching techniques. Building on these insights, we then replicated the cellular membranes of the most common bacterial strains. Finally, our investigation focused on replicating the lateral heterogeneities observed in vivo in the membranes of E. coli and B. subtilis. We anticipate that the proposed platforms, with their fully tunable lipid compositions, will be highly effective in elucidating the fundamental biological processes associated with bacterial cell membranes.