biostudies-literatureAziz UBABundesministerium für Bildung und Forschung (Federal Ministry of Education and Research)Bundesministerium für Bildung und ForschungDeutsche ForschungsgemeinschaftDeutsche Forschungsgemeinschaft (German Research Foundation)Investitionsbank Berlin3537https://www.ebi.ac.uk/biostudies/studies/S-EPMC11053136biostudies-literatureUnknown15(1)Pneumolysin (PLY) is a cholesterol-dependent cytolysin (CDC) from Streptococcus pneumoniae, the main cause for bacterial pneumonia. Liberation of PLY during infection leads to compromised immune system and cytolytic cell death. Here, we report discovery, development, and validation of targeted small molecule inhibitors of PLY (pore-blockers, PB). PB-1 is a virtual screening hit inhibiting PLY-mediated hemolysis. Structural optimization provides PB-2 with improved efficacy. Cryo-electron tomography reveals that PB-2 blocks PLY-binding to cholesterol-containing membranes and subsequent pore formation. Scaffold-hopping delivers PB-3 with superior chemical stability and solubility. PB-3, formed in a protein-templated reaction, binds to Cys428 adjacent to the cholesterol recognition domain of PLY with a K_D of 256 nM and a residence time of 2000 s. It acts as anti-virulence factor preventing human lung epithelial cells from PLY-mediated cytolysis and cell death during infection with Streptococcus pneumoniae and is active against the homologous Cys-containing CDC perfringolysin (PFO) as well.Nature communicationsTargeted small molecule inhibitors blocking the cytolytic effects of pneumolysin and homologous toxins.PMC11053136SFB 765, SFB 134901KI2110Trenkner TAziz UBAHocke ACRademann JAtef AHoelzemer ABottcher CSaoud ARudolf TLudwig KArkona CMieth MBermudez MWolber GfalseTargeted small molecule inhibitors blocking the cytolytic effects of pneumolysin and homologous toxins.Pneumolysin (PLY) is a cholesterol-dependent cytolysin (CDC) from Streptococcus pneumoniae, the main cause for bacterial pneumonia. Liberation of PLY during infection leads to compromised immune system and cytolytic cell death. Here, we report discovery, development, and validation of targeted small molecule inhibitors of PLY (pore-blockers, PB). PB-1 is a virtual screening hit inhibiting PLY-mediated hemolysis. Structural optimization provides PB-2 with improved efficacy. Cryo-electron tomography reveals that PB-2 blocks PLY-binding to cholesterol-containing membranes and subsequent pore formation. Scaffold-hopping delivers PB-3 with superior chemical stability and solubility. PB-3, formed in a protein-templated reaction, binds to Cys428 adjacent to the cholesterol recognition domain of PLY with a K_D of 256 nM and a residence time of 2000 s. It acts as anti-virulence factor preventing human lung epithelial cells from PLY-mediated cytolysis and cell death during infection with Streptococcus pneumoniae and is active against the homologous Cys-containing CDC perfringolysin (PFO) as well.2024-01-01T00:00:00Z2024 Apr2026-06-02T11:34:08.316Z2026-05-27T03:12:08.077ZS-EPMC110531363867093910.1038/s41467-024-47741-3