Employing a ZTP Riboswitch to Detect Bacterial Folate Biosynthesis Inhibitors in a Small Molecule High-Throughput Screen

Various riboswitch classes are being discovered that
precisely
monitor the status of important biological processes, including metabolic
pathway function, signaling for physiological adaptations, and responses
to toxic agents. Biochemical components for some of these processes
might make excellent targets for the development of novel antibacterial
molecules, which can be broadly sought by using phenotypic drug discovery
(PDD) methods. However, PDD data do not normally provide clues regarding
the target for each hit compound. We have developed and validated
a robust fluorescent reporter system based on a ZTP riboswitch that
identifies numerous folate biosynthesis inhibitors with high sensitivity
and precision. The utility of the riboswitch-based PDD strategy was
evaluated using Escherichia coli bacteria by conducting
a 128 310-compound high-throughput screen, which identified
78 sulfanilamide derivatives among the many initial hits. Similarly,
representatives of other riboswitch classes could be employed to rapidly
match antibacterial hits with the biological processes they target.