Image courtesy of Shutterstock/nobeastsofierce
Joel Kontinen
Life is thought to
have begun when RNA began replicating itself, and researchers have got close to
achieving this in the lab.
Could mankind do the impossible, create life from almost nothing?
The goal of
understanding how inert molecules gave rise to life is one step closer,
according to researchers who have created a system of RNA molecules that can
partly replicate itself. They say it should one day be possible to achieve
complete self-replication for the first time.
RNA is a key
molecule when it comes to the origins of life, as it can both store information
like DNA and catalyse reactions like proteins. While it isn’t as effective as
either of these, the fact that it can do both means many researchers believe
life began with RNA molecules that were capable of replicating themselves.
“This was the molecule that ran biology,” says James Attwater at
University College London.
But creating
self-replicating RNA molecules has proved difficult. RNA can form double
helices like DNA and can be copied in the same way, by splitting a double helix
in two and adding RNA letters to each strand to create two identical helices.
The problem is that RNA double helices stick together so strongly that it is
hard to keep the strands separate for long enough to allow replication.
Now, Attwater and
his colleagues have found that sets of three RNA letters – triplets – bind
strongly enough to prevent the strands rezipping. Three
is the sweet spot, says Attwater, as longer sets are likely to mispair. So, in
the team’s system, an RNA enzyme in double-helix form is mixed with triplets.
The solution is
made acidic and warmed to 80°C (176°F) to separate the helix, allowing the
triplets to pair up and form the “rungs” of the double helix. The solution is
then made alkaline and cooled to -7°C (19°F). As the water freezes, the
remaining liquid becomes highly concentrated and the RNA enzyme becomes active
and joins up the triplets, forming a new strand.
“RNA nucleotide
triplets serve very specific informatic functions in translation in all cells,”
says Zachary Adam at the University of Wisconsin-Madison. “This
paper is interesting because it might point to a purely chemical role – a
non-informatic function – for RNA nucleotide triplets that they could have
served prior to the emergence of a living cell.”
Source:
Michael Le Page 2025 We’re getting close to recreating the first step in evolution of life | New Scientist 28 May
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