Modified nucleic acids on display

Non-natural nucleic acids have offered insight into natural DNA and RNA and provided experimental systems to test theories of nucleic acid evolution. Numerous structurally modified nucleic acids have been prepared in the laboratory that show a diverse range of genetic and structural properties. One in particular, threose nucleic acid (TNA), has attracted attention because of its chemical simplicity and its ability to base-pair with complementary DNA, RNA and other TNA. Ichida et al. now show, in the Journal of the American Chemical Society, that long stretches of TNA can be synthesized by an engineered DNA polymerase, and they suggest a system for the in vitro selection of TNA molecules with novel functions.