19F‐NMR‐based fragment screening for 14 different biologically active RNAs and 10 DNA and protein counter‐screens

Binas, Oliver; de Jesus, Vanessa; Landgraf, Tom; Völklein, Albrecht Eduard; Martins, Jason; Hymon, Daniel; Berg, Hannes; Bains, Jasleen Kaur; Biedenbänder, Thomas; Fürtig, Boris; Gande, Santosh Lakshmi; Niesteruk, Anna; Oxenfarth, Andreas; Qureshi, Nusrat Shahin; Schamber, Tatjana; Schnieders, Robbin; Tröster, Alix; Wacker, Anna; Wirmer-Bartoschek, Julia; Martin, Maria Alexandra Wirtz; Stirnal, Elke; Azzaoui, Kamal; Blommers, Marcel Jules José; Richter, Christian; Sreeramulu, Sridhar; Schwalbe, Harald

We report here on the nuclear magnetic resonance (NMR) 19 F screening of 14 RNA targets with different secondary and tertiary structure to systematically assess druggability of RNAs. Our RNA targets include representative bacterial riboswitches that naturally bind with nanomolar affinity and high specificity to cellular metabolites of low molecular weight. Based on counter‐screens against five DNAs and five proteins, we can show that RNA can be specifically targeted. To demonstrate the quality of the initial fragment library that has been designed for easy follow‐up chemistry, we further show how to increase binding affinity from an initial fragment hit by chemistry that links the identified fragment to the intercalator acridine. Thus, we achieve low micromolar binding affinity without losing binding specificity between two different terminator structures.