Origins of life could have started with DNA-like XNAs

Nagoya University scientists in Japan have demonstrated how DNA-like molecules could have come together as a precursor to the origins of life. The findings, published in the journal Nature Communications, not only suggest how life might have begun, but also have implications for the development of artificial life and biotechnology applications.

"The RNA world is widely thought to be a stage in the origin of life," says Nagoya University biomolecular engineer Keiji Murayama.

"Before this stage, the pre-RNA world may have been based on molecules called xeno nucleic acids (XNAs). Unlike RNA, however, XNA replication probably didn't require enzymes. We were able to synthesize an XNA without enzymes, strongly supporting the hypothesis that an XNA world might have existed before the RNA world."

XNAs are formed of chains of linked nucleotides, similar to DNA and RNA but with a different sugar backbone. XNAs can carry genetic code very stably because the human body can't break them down. Some researchers have reported that XNAs containing specific sequences can act as enzymes and bind to proteins. This makes XNAs exciting in the field of synthetic genetics, with potential biotechnology and molecular medicine applications.

Murayama, Hiroyuki Asanuma and colleagues wanted to find out if conditions likely present on early Earth could have led to XNA chain formation. They synthesized fragments of acyclic (non-circular) L-threoninol nucleic acid (L-aTNA), a molecule that is thought to have existed before RNA came to be. They also made a longer L-aTNA with a nucleobase sequence that complemented the sequences of the fragments, similar to how DNA strands match up.

When placed together in a test tube under controlled temperature, the shorter L-aTNA fragments came together and linked up with each other on the longer L-aTNA template.

Critically, this happened in the presence of a compound, called N-cyanoimidazole, and a metal ion, like manganese, both of which were possibly present in early Earth. The fragments interlinked when a phosphate at the end of one chemically attached to a hydroxyl group at the end of its neighbour, without the help of an enzyme.

"To the best of our knowledge, this is the first demonstration of template-driven, enzyme-free extension of acyclic XNA from a random fragment pool, generating phosphodiester bonding," says Murayama.

The team also demonstrated that L-aTNA fragments could interlink on DNA and RNA templates. This suggests that genetic code could be transferred from DNA and RNA onto L-aTNA and vice versa.

"Our strategy is an attractive system for experimenting with the construction of artificial life and the development of highly functional biological tools composed of acyclic XNA," says Murayama. "The data also indicate that L-aTNA could have been an RNA precursor."

The team plans to continue their investigations to clarify whether L-aTNA could have been synthesized in early Earth 'pre-life' conditions and to examine their potential for developing advanced biological tools.

Research Report: "Nonenzymatic polymerase-like template-directed synthesis of acyclic L-threoninol nucleic acid"

Related Links
Nagoya University
Lands Beyond Beyond - extra solar planets - news and science
Life Beyond Earth

Tweet

Thanks for being there;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Monthly Supporter
$5+ Billed Monthly

paypal only

SpaceDaily Contributor
$5 Billed Once

credit card or paypal

Photosynthesis could be as old as life itself
London, UK (SPX) Mar 29, 2021
Researchers find that the earliest bacteria had the tools to perform a crucial step in photosynthesis, changing how we think life evolved on Earth. The finding also challenges expectations for how life might have evolved on other planets. The evolution of photosynthesis that produces oxygen is thought to be the key factor in the eventual emergence of complex life. This was thought to take several billion years to evolve, but if in fact the earliest life could do it, then other planets may have evo ... read more