The DNA of life on Earth naturally stores its information in just four key chemicals — guanine, cytosine, adenine and thymine, commonly referred to as G, C, A and T, respectively.
Now scientists have doubled this number of life’s building blocks, creating for the first time a synthetic, eight-letter genetic language that seems to store and transcribe information just like natural DNA.
In a study published on 22 February in Science1, a consortium of researchers led by Steven Benner, founder of the Foundation for Applied Molecular Evolution in Alachua, Florida, suggests that an expanded genetic alphabet could, in theory, also support life.
“It’s a real landmark,” says Floyd Romesberg, a chemical biologist at the Scripps Research Institute in La Jolla, California. The study implies that there is nothing particularly “magic” or special about those four chemicals that evolved on Earth, says Romesberg. “That’s a conceptual breakthrough,” he adds.
Normally, as a pair of DNA strands twist around each other in a double helix, the chemicals on each strand pair up: A bonds to T, and C bonds with G.
For a long time, scientists have tried to add more pairs of these chemicals, also known as bases, to this genetic code. For example, Benner first created ‘unnatural’ bases in the 1980s. Other groups have followed, with Romesberg’s lab making headlines in 2014 after inserting a pair of unnatural bases into a living cell.