The DNA double helix that we’re all familiar with is a molecular ladder made of three key parts. The backbone of phosphates that tie everything together up and down, the sugar rings (“deoxyribose”) that serve as rungs, and the bases (A, C, G, T) that invisibly bond the two strands of the helix together, head to toe.
But that helix can be broken or mutated in nature, leading to mutations. And out of all the compounds in the world that could have evolved to carry our information, why just DNA and its cousin RNA? To answer that question, Vitor Pinheiro’s team created a completely new set of information molecules called XNA.
XNA replaces the deoxyribose sugar ring with other chemical rings like threose and cyclohexane. By evolving an enzyme that could read these funny bases, they were able to read DNA into XNA as well as the reverse. Plus it’s super-strong and resistant to breaking or cleaving.
Molecules like XNA could expand the information code for synthetic biology as well as help us answer the ultimate question about DNA: Why that, and not something else? Ed Yong has more great detail here.