A new reverse transcriptase copies lengthy transcripts

Reverse transcriptase is an enzyme that converts an RNA template molecule to DNA. By conserving sequence information and enabling easy amplification, this enzyme allows scientists to investigate RNA. Researchers from the Pyle lab at Yale have characterized a novel reverse transcriptase which can be engineered into a powerful biotechnological tool.

“We found it by accident when trying to solve a crystal structure of a new type of reverse transcriptase,” said Anna Pyle, Yale professor of Molecular, Cellular, and Developmental Biology. This reverse transcriptase family interacts with group II introns, mobile genetic elements that shape genomes of bacteria, fungi, and plants. After identifying the most stable member of the enzyme family, her lab not only revealed its atomic scale shape but also found that it possessed remarkable enzymatic activity.

When converting an RNA molecule into DNA, conventional reverse transcriptases cannot produce long DNA fragments, resulting in piecewise conversion of RNA to DNA and limiting applications for long RNA sequences. However, the newly-discovered reverse transcriptase efficiently copies very long transcripts completely. Thus, the researchers named the enzyme “MarathonRT” in tribute to its impressive endurance.

“Because MarathonRT can handle very long RNAs, it can be used to monitor multiple changes in the transcript,” said Pyle. For example, her lab is collaborating to decode alterations of HIV RNA genome in response to drug therapy. Using MarathonRT, the whole HIV genome sequence can be analyzed to reveal relationships between multiple mutations. MarathonRT has been already distributed to 60-70 labs around the world, suggesting its significant implications to many fields in science and medicine.