© BRYAN SATALINOWhen James Watson and Francis Crick announced in 1953 that they had determined the double-helical structure of DNA, the letters G, T, A, and C were forever embedded in the collective mind of the biology world. The arrangement of these four nucleotide bases in a strand of DNA dictates the sequence of an organism’s every protein.
These days, synthetic biologists can treat those four bases as the programming language underlying protein design. The field is grappling with how best to manipulate this blueprint that “makes a hummingbird into a hummingbird and not into a cow,” says Claes Gustafsson, cofounder of a bioengineering company called ATUM (formerly DNA2.0).
Scientists have known for decades how to manufacture DNA in the lab, in principle allowing them to manipulate life in ways that Watson and Crick couldn’t have imagined—inserting genes into bacteria, yeast cells, or algae to produce enzymes from different organisms, or encoding proteins that fold into shapes not found in nature.
But in practice, discerning the precise DNA sequence that gives rise to a certain protein, or predicting how a sequence will behave ...
