Increasing resistance to antibiotics necessitates discovery of new targets and strategies to combat bacteria. Ideal protein targets are required for viability across many species, are unique to prokaryotes to limit effects on the host and have robust assays to quantitate activity and identify novel inhibitors. Lipoprotein signal peptidase (Lsp) is a transmembrane aspartyl protease required for lipoprotein maturation and entirely fits these criteria. We have developed the first in vitro high-throughput assay to monitor proteolysis by Lsp. We employed our HTS assay against 646,275 compounds to discover inhibitors of Lsp and synthesized a range of analogues to generate molecules with nanomolar IC50 values. Importantly, our inhibitors are effective in preventing the growth of E. coli cultures. Our Lsp assay will be a useful tool for biologists to monitor Lsp activity and our inhibitors will facilitate development of antibacterial agents to potentially treat antibiotic-resistant bacteria.
