Biological Cruise Control Engineered into Living Cells

Cars have cruise control. Jet planes have auto pilot. Factories have industrial process control. And now, thanks to synthetic biology, cells have human-engineered integral feedback control. In a proof-of-concept study, Escherichia coli bacteria have been equipped with a controller in the form of a cybergenetic regulatory network, that is, a set of interacting biological circuit elements. These elements accomplish for bacterial cells what integral feedback loops have long accomplished in industrial plants—which is fitting, since bacterial cells and other types of cells are used as tiny chemical factories in biotechnology applications. Just as integral feedback loops sustain optimal productivity on the factory floor, such feedback loops could ensure that producer cells release desirable products—vitamins, medications, chemicals, and biofuels—at high, stable rates. Integral feedback loops could also result in designer cells that could maintain optimal levels of chemicals inside a patient’s body, helping resolve conditions such as diabetes or thyroid deficiency. Finally, they could improve cancer immunotherapy, ensuring that immune cells are active enough to fight tumors but restrained enough to avoid attacking healthy tissue.