For 3 billion years, an integral part of life on Earth has been the creation of complementary DNA from RNA templates. While controversial when first discovered, the process has become widely accepted. Yet despite its longevity, it is still constantly and notoriously riddled with errors. Thankfully, this 3-billion-year-old glitch could soon have a modern fix.
Reverse transcription is the process whereby an enzyme synthesizes DNA from an RNA template. While the error-prone ways of these proteins may have contributed to the plethora of unique species on this planet, its lack of proofreading has also caused just as many problems.
Now, researchers at the University of Texas at Austin have engineered a “near-perfect” solution: An enzyme that performs both reverse transcription and “proofreads” for errors. This increases its accuracy, which in turn may lead to improved medical diagnoses and genetic research. The study was published this week in Science.
"With proofreading, our new enzyme increases precision and fidelity of RNA sequencing," said Jared Ellefson, a postdoctoral fellow in UT Austin's Center for Systems and Synthetic Biology, in a statement. This is no mean feat, as “without the ability to faithfully read RNA, we cannot accurately determine the inner workings of cells. These errors can lead to misleading data in the research lab and potential misdiagnosis in the clinical lab.”
To perform this feat of molecular engineering, the team created a new and improved group of enzymes via directed evolution, whereby they trained the enzymes to read genetic information inside living cells with unprecedented accuracy. Called RTX, this new enzyme performs the original function of copying RNA, while also reviewing its work and correcting for errors.
"As we move towards an age of personalized medicine where everyone's transcripts will be read out almost as easily as taking a pulse, the accuracy of the sequence information will become increasingly important," added senior study author Andrew Ellington. "The significance of this is that we can now also copy large amounts of RNA information found in modern genomes, in the form of the RNA transcripts that encode almost every aspect of our physiology. This means that diagnoses made based on genomic information are far more likely to be accurate."
Image in text: Commonly associated with retroviruses such as HIV, the error-prone ways of these viruses may have added to the complexity of life on Earth. Wikimedia Commons