In the rapidly evolving world of modern medicine, RNA molecules have become indispensable, playing crucial roles in vaccines, diagnostics, and groundbreaking gene therapies. However, as the demand for these molecules rises, a significant challenge emerges: the need to produce RNA swiftly, accurately, and with sufficient versatility for future biomedical innovations.
Researchers at the University of California, Irvine have made substantial progress towards addressing this challenge. In a recent study featured in Nature Chemical Biology, a team led by John Chaput, a professor of pharmaceutical sciences at UC Irvine, has successfully developed a remarkable new enzyme that synthesizes RNA efficiently—something that natural DNA-copying enzymes are unable to achieve. This engineered enzyme, referred to as C28, operates at speeds comparable to those of natural processes while ensuring high precision and the capability to replicate lengthy sequences.
"DNA polymerases are inherently programmed to reject RNA," Chaput explained. "What took us by surprise was our ability to overcome this limitation not by redesigning the active site of the enzyme but by allowing evolution to reveal unexpected structural solutions."
Instead of manually crafting the enzyme, the researchers utilized a method known as directed evolution. They employed a high-throughput, single-cell screening platform to recombine related polymerase genes, testing millions of enzyme variants simultaneously. Remarkably, after just a few selection rounds, they discovered C28—an enzyme harboring numerous mutations throughout its structure that collectively facilitate effective RNA synthesis.
The result is an enzyme endowed with unique capabilities. Beyond synthesizing RNA, C28 can also perform reverse transcription, converting RNA back into DNA, and is capable of generating hybrid DNA-RNA molecules through standard polymerase chain reaction methods. Additionally, this enzyme can easily incorporate several chemically modified RNA building blocks, including those utilized in mRNA vaccines and RNA-based therapeutic approaches.
This combination of rapid production, accuracy, and adaptability positions C28 as an invaluable asset for researchers and biotechnology developers, especially in areas requiring tailored or chemically altered RNA molecules.
Moreover, this research highlights the potential of directed evolution as a powerful tool for creating novel molecular functions—abilities that do not exist in the natural world but can be achieved through meticulously designed selection strategies.
"This work demonstrates that enzymes possess a level of adaptability far greater than we previously imagined," Chaput noted. "By leveraging evolution, we can develop innovative molecular tools that pave the way for advancements in RNA biology, synthetic biology, and biomedical breakthroughs."
The research team also included members Esau Medina, Victoria Maola Gross, Mohammad Hajjar, Ethan Ho, Alexandria Horton, Nicholas Chim, and Grace Ko. The National Science Foundation provided funding for this important research.
