Reprogramming bacteria to seek and destroy an herbicide

Abstract

A major goal of synthetic biology is to reprogram cells to perform complex tasks. Here we show how a combination of in vitro and in vivo selection rapidly identifies a synthetic riboswitch that activates protein translation in response to the herbicide atrazine. We further demonstrate that this riboswitch can reprogram bacteria to migrate in the presence of atrazine. Finally, we show that incorporating a gene from an atrazine catabolic pathway allows these cells to seek and destroy atrazine. A major goal of synthetic biology is to program cells to autonomously perform complex tasks, such as synthesizing small molecules, delivering drugs, or cleaning up the environment. For cells to act autonomously, they must be able to sense cues from their environment and react predictably. Bacteria, such as E. coli, have evolved a variety of protein-based environmental sensors that respond to chemical signals such as amino acids, dipeptides, and sugars1–3. In principle, the specificity of these protein sensors can be reengineered by either rational design or evolution-based methods4–7, but these methods typically require a pre-existing scaffold, and dramatically altering the ligand specificity of