Disarming Streptococcus mutans in real time: live-cell DARTS uncovers ABC transporter targeting by manool

Antimicrobial resistance poses a significant threat to global health, highlighting the urgent need for novel therapeutic agents. Plant-derived compounds are a promising source of antimicrobial compounds. Given their huge structural variability, they putatively operate through a multiplicity of modes of action, interacting with various targets. The implementation of appropriate approaches aimed at reliably describe the molecular mechanism of these compounds, allows identifying promising hits, and new pharmacologically exploitable proteins. Here, we investigated the antimicrobial activity of manool, a diterpene isolated from Salvia officinalis L. (Lamiaceae), against the dental pathogen Streptococcus mutans . Using compound-centric proteomic techniques, we identified ATP-binding cassette (ABC) transporters as key targets of manool. These proteins are involved in nutrient uptake and in bacterial drug resistance. Implementing metabolomics approaches, we showed that manool inhibits ABCs, thereby impairing energy metabolism and delaying bacterial proliferation, and. enhancing the efficacy of the antibiotic kanamycin. Finally, based on the docking and molecular dynamics results we hypothesized that manool is able to interfere with the activity of various ABCs by occupying their ATP binding domain. This is the first time that ABCs have emerged from a completely untargeted approach as proteins responsible for the bioactivity of an antibacterial agent.