3P-406 : Artificial lactam riboswitch as an intracellular metabolite sensor for high-throughput screening and selection

Caprolactam is is a cyclic amide of caproic acid and is widely used to produce nylon-6 through ring-opening polymerization. An intracellular biosensor for caprolactam can facilitate high-throughput metabolic engineering of recombinant microbial strains. Because of the mixed production of caprolactam and valerolactam in the recombinant strain, a caprolactam biosensor should be highly specific for caprolactam. However, a highly specific caprolactam sensor has not been reported. Here, we developed a specific caprolactam riboswitch useful for monitoring the intracellular concentration of caprolactam. The riboswitch developed through coupled in vitro-in vivo selection responded specifically to caprolactam. Finally, caprolactam-dependent control of cell growth was demonstrated using the riboswitch. This riboswitch is a valuable tool for directed evolution of enzymes and pathway optimization for the microbial production of caprolactam.