When life began on Earth, the iron may have done work in various aspects of magnesium, making life possible in an environment very different from today.
In the periodic table of elements, iron and magnesium are removed. But a new finding suggests that the last three billion years, the iron did the job that magnesium does today for the ribonucleic acid (RNA), a molecule essential for life, assume the forms necessary for molecular biology.
There are enough indications that the evolution of life passed through an archaic stage during which RNA played a role, doing work in many aspects of DNA and proteins before their appearance. In that distant past, more than three billion years, the environment devoid of oxygen, but had plenty of available iron.
As pointed by Carl Pilcher, director of the NASA Astrobiology, one of the biggest challenges in astrobiology is to understand how life began on Earth billions of years, when the environment was very different from today. The new study results suggest how the conditions on early Earth could be conducive to the development of life.
In this study, the team of Loren Williams, Georgia Institute of Technology (Georgia Tech) in Atlanta, USA, performed experiments and numerical calculations to show that in a scenario with the same conditions of early Earth, including a dearth of oxygen, iron is able to replace magnesium and allow the RNA to assume the forms needed to catalyze the chemical reactions of the simple life. In fact, this primitive RNA catalyzed reactions better with the iron with magnesium.
The main motivation of this research was to glimpse the role of RNA under the most likely early Earth. The hypothesis of Williams and colleagues is that RNA evolved in the presence of iron and is optimized to run on that item.
Free gaseous oxygen was almost nonexistent in the Earth’s atmosphere for more than three billion years when oxygen began to enter the environment as a product of photosynthesis, oxidized iron and available land, forming massive banded iron deposits. The recent study indicates that RNA then began to use magnesium, resulting in the development of life as we know it today.
In future studies, the researchers plan to investigate which functions of RNA can be made with iron and magnesium.
The investigation was also worked by Shreyas Athavale, Anton Petrov, Roger Wartell, Stephen Harvey, Nicholas Hud and Chiaolong Hsiao, all from Georgia Tech.
The study was funded by the Astrobiology Institute at NASA, led from the Research Center NASA Ames, Moffett Field, California.