What if the behavior of natural and synthetic cells could be programmed like computers? Then a programmer could turn cellular behaviors on and off in a living organism by adding certain molecules. Cells already sense and respond to stimuli. But with external control, those behaviors could be put to work in medical or biotechnological tasks—for example, as smart drug delivery or telling bacteria to clean up toxic waste. To that end, researchers have engineered logic gates, largely using DNA and RNA, that introduce programmable circuitry into cells.
Although those nucleic-acid logic gates are easy to program, cells make decisions through protein–protein interactions. A protein-based logic gate can speak directly to a cell’s existing decision-making circuits. Researchers have already modified naturally occurring protein signals to introduce new logic pathways. But those implementations are inherently limited in scope by the number, properties, and geometries of the proteins.
Now David Baker of the...
