Iron and sulfur: the ingredients of the first ‘breath’ of life on Earth

A new research study coordinated by Sheref Mansy of the University of Trento identified, for the first time, the biochemical mechanism that enables cell metabolism, the process that makes the development of any life form possible. According to the study, which was published in Nature Catalysis, iron and sulfur on the young Earth about 4 billion years ago were the main starters of the chemical processes that led to the birth of life on our planet.
The research takes off from the results achieved last year by Sheref Mansy’s team, which had discovered the importance of iron-sulfur clusters in prebiotic evolution, activated by ultraviolet light irradiation emitted by the Sun. As the article in Nature Catalysis explains, the new study moves one step forward by recognizing the key role that these elements played in the formation of the first cellular forms that then led to more complex life forms.
All living organisms use the energy produced by digestion to fuel the vital processes that support life. This phenomenon is known as metabolism and its functioning is based on a series of chemical transformations that occur within cells. The work of Mansy and his team demonstrates that iron-sulfur clusters were the first to lead to the creation of so-called pH gradients, i.e. the chemical mechanisms that allow communication across cell membranes. This is a fundamental process through which cells collect energy, and the metabolic activity that keeps living organisms alive relies on it. Therefore iron and sulfur, basic ‘building blocks’ on the very young Earth, made life possible on our planet.
“Without iron and sulfur – explained Sheref Mansy, researcher at CIBIO-Centre for Integrative Biology of the University of Trento and leader of the study – life on Earth might have evolved in a very different way. Iron, in particular, probably determined the chemical mechanism that later became cell metabolism”.
This result not only explains the origin of the first organic molecules on Earth, but may also help find any other life forms in the Universe. Only a few days ago, for instance, the presence of liquid water on Mars was confirmed by an Italian research team: it is not unlikely that these iron-sulfur clusters played a part in the development of primitive living organisms on the red planet. 
“Mars is red because of iron oxides – commented Mansy. This element is present in the Martian soil even more than in the Earth’s soil. And since sulfur too is important on the red planet, I would not be surprised if primitive life forms based on the iron-sulfur chemistry were discovered.
The study, recently published in Nature Catalysis, was funded by the Simons Foundation and the Armenise-Harvard Foundation.
Sheref Mansy, research leader, moved to Trento in 2009 after receiving the Career Development Award from the Armenise-Harvard Foundation, and opened the Origins of Life and Synthetic Biology Lab at CIBIO. The purpose of the laboratory is to find a middle ground between living and non-living systems at cellular level: in particular, to build cells that can “breathe” artificially. This work may help identify with increasing precision the biochemical mechanisms that made the first signs of life possible on Earth.