Hydrogen peroxide as driver for the RNA world

What is it about?

In a series of four recent papers we have developed and tested the hypothesis that hydrogen peroxide was essential to the development of the RNA world on Earth more than 3.7 billion years ago, and that it set the scene for the emergence of cellular life. This is the second paper in the series.  It is now accepted that primordial non-cellular RNA communities must have been subject to a periodic drive in order to replicate and prosper. We have proposed the oxidation of thiosulfate by hydrogen peroxide as this drive. This reaction system behaves as (i) a thermochemical and (ii) a pH oscillator, and in this work, we unify (i) and (ii) for the first time. We report thermally self- consistent, dynamical simulations in which the system transitions smoothly from nearly isothermal pH to fully developed thermo-pH oscillatory regimes. We use this oscillator to drive simulated replication of a 39-bp RNA species. Production of replicated duplex under thermo-pH drive was significantly enhanced compared with that under purely thermochemical drive, effectively allowing longer strands to replicate. Longer strands are fitter, with more potential to evolve enzyme activity and resist degradation. We affirm that concern over the alleged toxicity of hydrogen peroxide to life is largely misplaced in the current context, we survey its occurrence in the solar system to motivate its inclusion as a biosignature in the search for life on other worlds and high- light that pH oscillations in a spatially extended, bounded system manifest as the fundamental driving force of life: a proton gradient.

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Why is it important?

Overall, we have generated results which we hope can constitute a recipe for definitive experiments, which could demonstrate that hydrogen peroxide may have powered the RNA world, and fill in some more pieces of the greatest puzzle in biology - the origin of life.

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