The Amyloid Hypothesis: Rewriting Life’s Origin Story

The mystery of how living organism originated from non-living matter is still one of the most profound puzzles in science. Despite various theories, a definitive explanation remains elusive, which is not surprising given that these events took place three to four billion years ago in vastly different conditions on Earth.

Justifying hypotheses with experimental data

“In the extensive course of time, evolution has erased the traces leading back to the origins of life,” explains Roland Riek, Professor of Physical Chemistry and Associate Director of ETH Zurich’s interdisciplinary Centre for Origin and Prevalence of Life. Science must rely on formulating hypotheses and supporting them with experimental data as comprehensively as possible.

Riek and his colleagues have been investigating the possibility for years that amyloids, clumps resembling proteins, were a significant factor in the transition from chemistry to biology. Their research initially demonstrated that these amyloids could readily form under conditions likely present on early Earth. In the laboratory, the process involves combining simple amino acids with a touch of volcanic gas, experimental skill, and considerable patience, leading to the spontaneous assembly of short peptide chains into fibers.

Precursor molecules of living organism

Subsequently, Riek’s team showcased that amyloids can replicate themselves, meeting another crucial criterion for being regarded as life’s precursor molecules. In their latest study, the researchers have once again followed this line, revealing that amyloids can bind with molecules of both RNA and DNA.

The interactions are influenced by electrostatic attraction, as certain amyloids have positive charges. At the same time, genetic material carries a negative charge, especially in a neutral to acidic environment. Additionally, Riek and his team observed that the sequence of RNA and DNA nucleotides influences these interactions. This suggests a potential precursor to the universal genetic code all living beings share.

Increased stability as a significant advantage

While differences in the binding of RNA and DNA molecules with amyloids remain unclear, Riek notes, “Our model is probably still too simple.” Emphasizing another crucial aspect, he highlights that when genetic material attaches to amyloids, both molecules gain stability, suggesting that this increased stability could have been a significant advantage in ancient times.

In the primordial soup of ancient times, biochemical molecules were highly dilute, unlike the densely packed environment within today’s biological cells. Riek’s researchers emphasize that amyloids have demonstrated the ability to enhance nucleotides’ local concentration and order in an otherwise diluted and disordered system, as stated in their recently published article.

Riek highlights that while Darwin’s theory emphasizes competition, cooperation has also played a significant evolutionary role. Both molecule classes benefit from the stabilizing interaction with amyloids and RNA or DNA molecules, as long-lived molecules accumulate more robustly over time than unstable ones. Riek suggests that molecular cooperation, rather than competition, might have been the decisive factor in the emergence of life, especially considering the likely abundance of space and resources in ancient times.

Read the original article on: SciTechDaily

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