Scientists discover that RNA segments can be written back into DNA

A group of researchers at Thomas Jefferson University have provided the first evidence that RNA segments can be written back into DNA. The discovery has the potential to change some of the central assumptions in biology and may have implications impacting many fields of biology. The discovery could open the door to other studies to help scientists understand the significance of a mechanism that's able to convert RNA messages into DNA in our own cells.

Researcher Richard Pomerantz, Ph.D. says that the reality that human polymerase can do this with high efficiency raises questions. One example is that the discovery suggests RNA messages could be used as templates to repair or rewrite genomic DNA.

In the experiments, the team tested polymerase theta against reverse transcriptase from HIV, one of the most studied. They were able to show that polymerase theta was capable of converting RNA messages into DNA. Interestingly, the team found that it was able to convert RNA messages into DNA as well as HIV reverse transcriptase. Furthermore, polymerase theta was more efficient and introduced fewer errors when using an RNA template to write new DNA messages than when duplicating DNA into DNA.

The team says this suggests the function could be its primary purpose inside the cell. Researchers on the project used x-ray crystallography to define the structure. They found the molecule could change shape to accommodate a more bulky RNA molecule, something unique amongst polymerases.

Dr. Pomerantz says the team's research indicates polymerase theta's primary function is to act as a reverse transcriptase. The purpose of the molecule may be aimed at RNA-mediated DNA repair. Researchers say that polymerase theta is highly expressed in cancer cells and promotes the growth of cancer cells and drug resistance.