Abstract
The increasing prevalence of antibiotic resistance demands the discovery of antibacterial chemical scaffolds with unique mechanisms of action. Phenotypic screening approaches, such as the use of reporters for bacterial cell stress, offer promise to identify compounds while providing strong hypotheses for follow-on mechanism of action studies. From a collection of ∼1,800 Escherichia coli GFP transcriptional reporter strains, we identified a reporter that is highly induced by cell envelope stress-pProm rcsA -GFP. After characterizing pProm rcsA -GFP induction, we assessed a collection of bioactive small molecules for reporter induction, identifying 24 compounds of interest. Spontaneous suppressors to one compound in particular, MAC-0452936, mapped to the gene encoding the essential prolipoprotein diacylglyceryl transferase, lgt. Lgt inhibition by MAC-0452936 inhibition was confirmed through genetic, phenotypic, and biochemical approaches. The oxime ester, MAC-0452936, represents a useful small molecule inhibitor of Lgt and highlights the potential of using pProm rcsA -GFP as a phenotypic screening tool.