RNA molecules can store genetic information and replicate themselves through the formation of double-stranded helices. The combination of these abilities enables them to mutate, evolve, adapt to different environments, and ultimately encode the protein building blocks of life. To do this, the RNA strands must not only replicate into a double strand, but also separate again in order to complete the replication cycle. However, the separation of the strands is a difficult task due to the high salt and nucleic acid concentrations required for replication.
“Various mechanisms have been studied for their potential to separate DNA strands at the origin of life, but they all require temperature changes that would lead to degradation of nucleic acids,“ says lead author Philipp Schwintek, a PhD student in Systems Biophysics group of ORIGINS scientist Dieter Braun at LMU. “We investigated a simple and ubiquitous geological scenario where water movement through a rock pore was dried by a gas percolating through the rock to reach the surface. Such a setting would be very common on volcanic islands on early Earth which offered the necessary dry conditions for RNA synthesis.”
The team built a laboratory model of the rock pore featuring an upward water flux evaporating at an intersection with a perpendicular gas flux, which leads to an accumulation of dissolved molecules at the interface. At the same time, the gas flux induces circular currents in the water, forcing molecules back into the bulk. To understand how this model would affect nucleic acids within the environment, they used beads to monitor the dynamics of the water flow and then tracked the movement of fluorescently labelled short DNA fragments.
Three-fold accumulation of DNA strand within five minutes
Within five minutes of starting the experiment, there was a three-fold accumulation of DNA strands, whereas after an hour, there were 30 times more DNA strands accumulated at the interface. Although this suggests that the gas/water interface allows for a sufficient concentration of nucleic acids for replication to occur, separation of the double stranded DNA is also necessary. Usually a change in temperature is required, but when the temperature is constant, changes in salt concentration are necessary.
“In this work we investigated a plausible and abundant geological environment that could trigger the replication of early life,” concludes Dieter Braun. “We considered a setting of gas flowing over an open rock pore filled with water, without any change in temperature, and found that the combined gas and water flow can trigger salt fluctuations which support DNA replication. Since this is a very simple geometry, our findings greatly extend the repertoire of potential environments that could enable replication on early planets.”
Publication:
Philipp Schwintek, Emre Eren, Christof Mast, Dieter Braun. Prebiotic gas flow environment enables isothermal nucleic acid replication. eLife 2024
Contact:
Prof. Dr. Dieter Braun
Ludwig-Maximilians-Universität München / Exzellence Cluster ORIGINS
email: Dieter.Braun(at)physik.uni-münchen.de
