RNA and DNA may no longer be the only candidates capable of evolving and building life forms around themselves. It is also likely, from the evolutionary standpoint, that RNA, and its likely successor DNA, might not have been the original replicators in the primordial soup either, as they have evolved from some earlier, more simple replicators. So a search has been on in the scientific community to create original self-replicating molecular systems. A team of international researchers has now developed six synthetic alternatives to our own genetic molecules that are capable of storing and transmitting information. Dubbed “XNA,” the new genetic material is also capable of undergoing evolution. In addition, XNA happens to also be stronger than DNA.
The “X” in XNA stands for “xeno-,” which is derived from the ancient Greek prefix meaning “alien” or “foreign.” Science magazine proclaims that the breakthrough could be the beginning of “a new era of synthetic genetics” with implications for exobiology—a field that investigates the potential for life outside of Earth as well as the impact of extraterrestrial environments on living organisms
The breakthrough could also be a boon to the field of biotechnology, potentially spurring the development of new biotherapeutics and diagnostics. XNA could be used to mark pathogenic agents and may even shed light on the origin of genetic information itself from billions of years ago.
The scientists created XNA by substituting the natural sugar component of DNA with a polymer. Six types are reported to work, resulting in that many subtypes of XNA. The XNA molecules are also capable of withstanding the natural enzymes that degrade DNA and RNA.
From the abstract:
Genetic information storage and processing rely on just two polymers, DNA and RNA, yet whether their role reflects evolutionary history or fundamental functional constraints is currently unknown. With the use of polymerase evolution and design, we show that genetic information can be stored in and recovered from six alternative genetic polymers based on simple nucleic acid architectures not found in nature [xeno-nucleic acids (XNAs)]. We also select XNA aptamers, which bind their targets with high affinity and specificity, demonstrating that beyond heredity, specific XNAs have the capacity for Darwinian evolution and folding into defined structures. Thus, heredity and evolution, two hallmarks of life, are not limited to DNA and RNA but are likely to be emergent properties of polymers capable of information storage.
The research was led by Vitor Pinheiro and Philipp Holliger of the Medical Research Council Laboratory of Molecular Biology in Cambridge, UK with the assistance from colleagues from Denmark, Belgium, and the United States.