Nav: Home

Chemical evolution: Progenitors of the living world

January 17, 2018

RNA was probably the first informational molecule. Now chemists from Ludwig-Maximilians-Universitaet (LMU) in Munich have demonstrated that alternation of wet and dry conditions could have sufficed to drive the prebiotic synthesis of the RNA nucleosides found in all domains of life.

"And the Earth was without form and void" - before the emergence of life. Meanwhile, we know rather more about the early Earth, but how might the chemical structures that provide the basic subunits of today's hereditary molecules - RNA and DNA - have formed from simpler starting materials some 4 billion years ago? Under what conditions could these building blocks have then been linked into long chains that could not only encode information but also propagate it by self-reproduction? Many possible scenarios have been proposed for the phase of chemical evolution that preceded the emergence of the first biological cells. Now, researchers led by LMU chemist Professor Thomas Carell have extended these models by demonstrating a plausible route for the prebiotic synthesis of the 'nucleosides' that constitute the informational components of RNA.

Specifically, Carell and his colleagues have shown that nucleosides can be formed in a continuous process by exposing simple chemicals to the kinds of fluctuating physical conditions that would have prevailed in geothermally active areas characterized by volcanic activity on the early Earth. They begin with a mixture of formic acid, acetic acid, sodium nitrite and a few nitrogen-containing compounds, all of which have previously been shown to form from even simpler precursors under prebiotic conditions. The reaction mixture also contained nickel and iron, which are found in large amounts in the Earth's crust. The driving force for the chemical reactions is supplied by fluctuations in temperature and pH, together with wet/dry cycles, such as those that occur in the vicinity of periodically active hot springs or in strongly seasonal climates with alternating periods of precipitation and evaporation.

The core of the process is a series of reactions that gives rise to compounds called formamidopyrimidines, which can in turn be converted into the canonical purines (adenosine and guanosine) found in RNA. In a paper published last year, Carell and his team first described this FaPy pathway as a possible chemical scenario for the prebiotic synthesis of nucleosides. "This time around, we not only began with simpler precursor compounds, but chose conditions that would be expected to prevail in a plausible geological setting, such as hydrothermal springs on land," explains Sidney Becker, a PhD student in Carell's group and first author of the study. The paper has now appeared in one of the leading online, open-access journals, Nature Communications.

Notably, not only the canonical purine nucleosides found in RNA were synthesized in the new experiments, but also a whole series of closely related molecules. Even more strikingly, all of the modifications observed are known to occur in RNAs in all three domains of life - Eukaryota (animals and plants), Bacteria and Archaea - and are therefore essential components of functional genetic systems. Hence, they were most probably already present in the last common ancestor of all life forms. This in turn argues, says Becker, that these compounds must have been available on early Earth when biological evolution began. Indeed, the authors of the new study suggest that the non-canonical nucleosides could have played a crucial role in the phase of chemical evolution that preceded the emergence of the 'RNA world' (the term refers to a hypothetical period during which RNA molecules are thought to have served as chemical catalysts, in addition to storing genetic information, in primordial cells). Seen in this light, the RNA modifications found in today's organisms represent molecular fossils that have continued to participate in vital biological functions for billions of years.

Ludwig-Maximilians-Universität München

Related Rna Articles:

How RNA formed at the origins of life
A single process for how a group of molecules called nucleotides were made on the early Earth, before life began, has been suggested by a UCL-led team of researchers.
RNA and longevity: Discovering the mechanisms behind aging
Korean researchers suggests that NMD-mediated RNA quality control is critical for longevity in the roundworm called C. elegans, a popularly used animal for aging research.
Don't kill the messenger RNA
Success of new protein-making therapy for hemophilia opens door for treating many other diseases.
RNA modification important for brain function
Researchers at the Institute of Molecular Biology (IMB) and Johannes Gutenberg University Mainz (JGU) have shown that a new way of regulating genes is vital for the activity of the nervous system.
Atlas of the RNA universe takes shape
In the last few years, small snippets of RNA, which may have played a key role in the planet's earliest flickering of life, have been uncovered and examined in great detail.
Punching cancer with RNA knuckles
Researchers achieved an unexpected eye-popping reduction of ovarian cancer during successful tests of targeted nanohydrogel delivery in vivo in mice.
Gatekeeping proteins to aberrant RNA: You shall not pass
Berkeley Lab researchers found that aberrant strands of genetic code have telltale signs that enable gateway proteins to recognize and block them from exiting the nucleus.
Short RNA molecules mapped in single cell
Researchers at Karolinska Institutet have measured the absolute numbers of short, non-coding, RNA sequences in individual embryonic stem cells.
Watching RNA fold
New technology takes a nucleotide-resolution snapshot of RNA as it is folding, which could lead to discoveries in biology, gene expression, and disease.
Bacteria: Third RNA binding protein identified
Pathogenic bacteria use small RNA molecules to adapt to their environment.

Related Rna Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Moving Forward
When the life you've built slips out of your grasp, you're often told it's best to move on. But is that true? Instead of forgetting the past, TED speakers describe how we can move forward with it. Guests include writers Nora McInerny and Suleika Jaouad, and human rights advocate Lindy Lou Isonhood.
Now Playing: Science for the People

#527 Honey I CRISPR'd the Kids
This week we're coming to you from Awesome Con in Washington, D.C. There, host Bethany Brookshire led a panel of three amazing guests to talk about the promise and perils of CRISPR, and what happens now that CRISPR babies have (maybe?) been born. Featuring science writer Tina Saey, molecular biologist Anne Simon, and bioethicist Alan Regenberg. A Nobel Prize winner argues banning CRISPR babies won’t work Geneticists push for a 5-year global ban on gene-edited babies A CRISPR spin-off causes unintended typos in DNA News of the first gene-edited babies ignited a firestorm The researcher who created CRISPR twins defends...