Synthetic evolutionary origin of a proofreading reverse transcriptase

Making error-free DNA from RNA DNA polymerase enzymes copy DNA into new strands of identical DNA. Reverse transcriptase (RT) enzymes copy RNA into DNA. Unlike many DNA polymerases, RT enzymes do not have a proofreading function that checks for errors in the newly synthesized DNA. Ellefson et al. use in vitro directed evolution and protein engineering to build an error-correcting RT from a prokaryotic DNA polymerase. The RT “xenopolymerase” shows increased fidelity as compared to natural RTs and should streamline and increase the precision of transcriptomics methods. Science , this issue p. 1590