Was there anything before DNA and RNA? There might have been TNA, says New Scientist's Michael Marshall. Researchers have recently found that TNA, for threose nucleic acid, can perform one of RNA's key functions, Marshall says — storing genetic information and acting as an enzyme. While TNA is no longer found in nature, it may have been around to help the first forms of life on Earth to develop. And because it used threose instead of ribose or deoxyribose as its sugar base, Arizona State University's John Chaput tells Marshall TNA may have had an advantage over DNA and RNA because it was smaller and easier to form.
Chaput and his team have been studying TNA for some time, and have recently created a TNA molecule in the lab, Marshall says, which "folds into a three-dimensional shape and clamps onto a specific protein. These are key steps towards creating a TNA enzyme that can control a chemical reaction, just like RNA." Chaput doesn't think TNA was the original genetic material, mostly because "the chemistry of early Earth was so messy that TNA would not have arisen on its own," Marshall adds. But there's still a lot to learn about this molecule and its cousins — PNA (peptide nucleic acid), GNA (glycol nucleic acid), and ANA (amyloid nucleic acid) — and Chaput says he's just getting started.