Novel actinobacterial TrmD inhibitors to combat Gram-negative pathogens
Biological and Biomimetic Chemistry
Final Report Abstract
With the spread of multidrug resistances, infectious diseases have become a threat to the global health system again and discovery of novel anti-infectives is urgently needed. Actinobacteria remain one of the most promising sources for their discovery, but high-throughput screening campaigns have diminished inter alia due to a high discovery rate of known antibiotics addressing targets that already underwent resistance development. Here, we present the evaluation of an advanced high-throughput screen (HTS) making use of the differences of the human (Trm5) vs. bacterial (TrmD) m1G37 t-RNA methyltransferase through application to one of the largest actinobacterial extract and fraction libraries. From over 72.000 screened samples, we identified extracts from two actinobacteria strains to exhibit good selectivity against the TrmD over the Trm5 expressing cell line and correlated the shared metabolite 5-chlorotryptophan to observed shifts in minimal inhibitory concentrations (MICs). Genometabolomics analysis of the two producing strains indicated 5-chlorotryptophan incorporation into two distinct antibiotic non-ribosomal peptides, longicatenamycins and nonopeptins. The nonopeptins are derived from an uncommon biosynthetic machinery featuring multiple rare building blocks, as well as an uncommon initiation and offloading. The most active congener of this natural product family discovered in this study, nonopeptin D, inhibits several Gram-negative and Gram-positive pathogens including multidrug resistant strains down to nanomolar concentrations. Even though having successfully led to the identification of a chemically new NP family with antibiotic activity, we found our initial screen to be influenced by metabolic differences between the two developed cell lines leading to false positive hits. The screen is therefore currently further engineered towards a more robust identification of TrmD-targeting antibiotics.
Publications
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Interplay of emerging and established technologies drives innovation in natural product antibiotic discovery. Current Opinion in Microbiology, 75, 102359.
Bader, Chantal D.; Nichols, Angela L.; Yang, Dong & Shen, Ben
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The Natural Products Discovery Center: Release of the First 8490 Sequenced Strains for Exploring Actinobacteria Biosynthetic Diversity.
Kalkreuter, Edward; Kautsar, Satria A.; Yang, Dong; Bader, Chantal D.; Teijaro, Christiana N.; Fluegel, Lucas L.; Davis, Christina M.; Simpson, Johnathon R.; Lauterbach, Lukas; Steele, Andrew D.; Gui, Chun; Meng, Song; Li, Gengnan; Viehrig, Konrad; Ye, Fei; Su, Ping; Kiefer, Alexander F.; Nichols, Angela; Cepeda, Alexis J. ... & Shen, Ben
