Bacteria that do logic
A team engineers microbes to perform AND, OR, NAND and NOR logic operations
If the planet Vulcan had microbes, they might look something like this. Scientists have engineered bacteria that can perform four basic operations of logic: AND, OR, NAND and NOR.
By combining these logic units in various ways, it could be possible to engineer microbes with an internal “decision tree” logic that controls their behaviors. The technique, which is described in the Oct. 17 Science, could give scientists a new level of control when designing microbes for a variety of uses, such as fermenting biofuels or producing pharmaceuticals.
“It’s the first installation of logic gates for controlling gene expression in a living cell,” comments Kensaku Sakamoto, an expert in DNA computation at RIKEN Systems and StructuralBiologyCenter in Yokohama, Japan. “It’s a wonderful result, and a milestone in the efforts for artificial regulation of living systems.”
Christina Smolke and Maung Nyan Win of the California Institute of Technology in Pasadena added custom-designed snippets of DNA to the tail end of a gene, and then inserted that gene into either E. coli bacteria or cells of brewer’s yeast. When the cells transcribed the DNA into molecules of RNA — the first step toward making functional proteins — the snippets of code knotted up into 3-dimensional twists in the RNA. These twists can sense the presence of certain “input” molecules and respond by either destroying the RNA or leaving it intact.