Combining Cell Envelope Stress Reporter Assays in a Screening Approach to Identify BAM Complex Inhibitors

The development of new antibiotics is particularly problematic in Gram-negative bacteria due to the presence outer membrane (OM), which serves as a permeability barrier. Recently, β-barrel assembly machine (BAM), located OM and responsible for type protein (OMP) assembly, has been validated novel target antibiotics. Here, we identified potential BAM complex inhibitors using screening approach that reports on cell envelope σE Rcs stress Escherichia coli. Screening library consisting 316 953 compounds yielded five induced responses, while not inducing intracellular heat-shock response. Two (compounds 2 14) showed characteristics known inhibitors: synergy with OMP biogenesis mutants, decrease abundance various OMPs, loss integrity. Importantly, compound also inhibited BAM-dependent folding an vitro refolding assay purified reconstituted proteoliposomes.