Adding New DNA Letters Makes Novel Proteins Possible
3rd April 2019
Every other organism on Earth relies on a quartet of genetic bases: A (adenine), C (cytosine), T (thymine) and G (guanine). These fit together in pairs inside a double-stranded DNA molecule, A matching T and C, G. But in 2014 Dr Romesberg announced that he had synthesised a new, unnatural, base pair, dubbed X and Y, and slipped them into the genome of E. coli as well.
Kept supplied with sufficient quantities of X and Y, the new cells faithfully replicated the enhanced DNA—and, crucially, their descendants continued to do so, too. Since then, Dr Romesberg and his colleagues have been encouraging their new, “semisynthetic” cells to use the expanded alphabet to make proteins that could not previously have existed, and which might have properties that are both novel and useful. Now they think they have found one. In collaboration with a spin-off firm called Synthorx, they hope to create a less toxic and more effective version of a cancer drug called interleukin-2.