According to the RNA world hypothesis, the first replicators (structures capable of reproduction) on Earth were RNA molecules capable of catalyzing their own reproduction without the help of protein enzymes. However, it was not clear how such a molecule might arise from precursors incapable of catalytic activity.
It turns out that a ribozyme that can cleave other molecules can arise spontaneously because only a few conserved bases are needed to ensure its function. However, the problem remained of how exactly this property was preserved during biochemical evolution.
The researchers developed a model that simulates random breaks in simple RNA molecules that lack enzymatic activity. As a result, short RNA chains arose, which acted as primers for the synthesis of longer RNA chains. This non-enzymatic mechanism resulted in the production of large numbers of copies of the destroyed polymer, similar to how worms regenerate when cut into segments.
In the second model, spontaneously produced ribozymes that catalyze cleavage were added to a pool of polymeric RNA strands that they cut upon collision. Polymer chains are able to pair in a certain way. If one of the strands has a loop (hairpin), then it is possible to form an RNA molecule that acts as a hammerhead ribozyme, capable of carrying out its own cleavage. Subsequently, self-reproduction of this enzyme begins in accordance with the first model.
Polymer replication occurred based on temperature cycling between hot and cold phases (typical of day-night cycles), suggesting that ancient polymers may have relied on such cycles to reproduce. Inorganic surfaces such as rocks might also contribute to this process.
#BB.lv #evidence #RNA #world #discovered
2024-04-01 19:45:24
