What if life as we know it isn’t the only way life can exist?
Scientists in the UK have taken a monumental step toward answering this question by creating synthetic enzymes from artificial genetic material—molecules that don’t rely on the DNA or RNA found in all known life forms.
Instead, these enzymes are built from XNA (xeno nucleic acid), a lab-created genetic material that could revolutionize medicine, environmental cleanup, and even the search for extraterrestrial life.
The breakthrough comes from the same Cambridge laboratory where James Watson and Francis Crick first uncovered the structure of DNA in 1953.
Led by Philipp Holliger, the team has demonstrated that XNA can store genetic information and form enzymes, challenging the long-held belief that DNA and RNA are the only molecules capable of these functions.
This discovery isn’t just a scientific curiosity—it has real-world implications.
For example, XNA-based enzymes could be used to develop long-lasting medical treatments that interact with a patient’s RNA or to create organisms that clean up environmental pollutants.
Even more intriguing, it suggests that life on other planets might be built from entirely different molecular foundations.
A New Blueprint for Life
The team’s work centers on XNA, a synthetic molecule that mimics the structure of DNA and RNA but uses different sugars and molecules not found in nature.
Three years ago, Holliger’s team successfully synthesized XNA using the same bases as DNA and RNA—adenine, thymine, guanine, cytosine, and uracil—but replaced the natural sugars with artificial ones.
Now, they’ve gone a step further, folding XNA strands into enzymes capable of cutting, pasting, and manipulating genetic material.
These XNA enzymes can also build and break down molecules, a critical function for sustaining life.
“Our work with XNA shows that there’s no fundamental imperative for RNA and DNA to be prerequisites for life,” Holliger told New Scientist.
This finding opens the door to creating entirely new life forms and redefines our understanding of what life could look like—both on Earth and beyond.
Life Doesn’t Need DNA or RNA
For decades, scientists believed that DNA and RNA were the only molecules capable of storing genetic information and forming enzymes.
This assumption has shaped everything from our search for extraterrestrial life to our approach to medicine. But Holliger’s research flips this notion on its head.
XNA proves that life could theoretically exist without DNA or RNA.
This challenges the idea that life elsewhere in the universe must resemble life on Earth.
As Alex Taylor, a member of the research team, explained to The Independent, “The discovery raises the possibility that, if there is life on other planets, it may have sprung up from an entirely different set of molecules.”
This perspective shift has profound implications.
It means that the search for extraterrestrial life should broaden its scope, looking for signs of life based on entirely different chemistries.
It also suggests that life could exist in environments previously thought inhospitable, such as planets with extreme temperatures or chemical compositions.
How It Works
To understand the significance of XNA, it’s helpful to revisit the basics of DNA and RNA.
These molecules are made up of nucleotides, which consist of a sugar, a phosphate group, and a nitrogenous base.
The sugars in DNA and RNA—deoxyribose and ribose, respectively—are crucial to their function.
XNA replaces these natural sugars with artificial ones, creating a molecule that behaves similarly but is chemically distinct.
This makes XNA extremely robust and resistant to degradation by natural enzymes, which don’t recognize it as a biological molecule.
Holliger’s team has shown that XNA can not only store genetic information but also fold into complex shapes to form enzymes.
These enzymes can perform tasks like cutting and pasting genetic material, a key step in the replication and evolution of life.
“Until recently, it was thought that DNA and RNA were the only molecules that could store genetic information and, together with proteins, the only biomolecules able to form enzymes,” Holliger told BBC News.
“Our work challenges that assumption.”
From Medicine to Environmental Cleanup
The potential applications of XNA are vast. In medicine, XNA-based treatments could be designed to interact with a patient’s RNA, offering new ways to treat diseases at the genetic level.
Because XNA is not recognized by the body’s natural enzymes, it could provide long-lasting therapies that resist degradation.
“Our XNAs are chemically extremely robust and, because they do not occur in nature, they are not recognized by the body’s natural degrading enzymes,” Holliger explained.
“This might make them an attractive candidate for long-lasting treatments that can disrupt disease-related RNA.”
In the environment, XNA-based organisms could be engineered to break down pollutants or clean up contaminated sites.
These synthetic life forms could perform tasks that natural organisms cannot, offering new solutions to pressing environmental challenges.
The Search for Extraterrestrial Life
One of the most exciting implications of this research is its impact on the search for life beyond Earth.
If life can exist without DNA or RNA, then the criteria for identifying habitable planets and potential life forms must expand.
“It widens the possible number of planets that might be able to host life,” Taylor told The Independent.
This discovery encourages scientists to look for life in environments previously considered too extreme or chemically different from Earth.
Replication and Beyond
While XNA has demonstrated the ability to store genetic information and form enzymes, there’s one critical step it hasn’t yet mastered: self-replication.
For a molecule to truly support life, it must be able to copy itself, just as DNA and RNA do.
Holliger’s team is now working on this challenge, aiming to create XNA molecules that can replicate autonomously.
If successful, this would mark a major milestone in the creation of artificial life forms.
Redefining Life as We Know It
The creation of synthetic enzymes from XNA is more than a scientific achievement—it’s a paradigm shift.
By proving that life doesn’t require DNA or RNA, this research challenges our understanding of biology and opens up new possibilities for medicine, environmental science, and astrobiology.
As we continue to explore the potential of XNA, one thing is clear: the boundaries of life are far more flexible than we once thought.
Whether it’s developing groundbreaking medical treatments, cleaning up our planet, or searching for life on distant worlds, XNA offers a glimpse into a future where the possibilities are as vast as the universe itself.
Sources: New Scientist, The Independent, BBC News
