This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Where did the energy come from to power the chemical origin of life, and how did phosphate come to be the universal energy currency of cells? Biologists from the Institute of Molecular Evolution at Heinrich Heine University Düsseldorf (HHU) have uncovered a new source of energy that drove primordial chemical reactions on the early Earth forward to kick-start metabolism.
Their findings, now published in The FEBS Journal, identify phosphite and palladium, substances that naturally occur in H2-producing hydrothermal vents, as an inorganic precursor of ATP. All forms of life convert environmental sources of energy into adenosine triphosphate (ATP), the universal energy currency of cells. ATP is essential to life because it provides a source of chemical energy that cells can use to make the reactions of metabolism go forward.
Life requires an abundance of ATP, as two examples illustrate. A well-nourished human makes—and consumes—a body weight of ATP every day, while a tiny bacterium like Escherichia coli makes 10 body weights of ATP during every cell division. Where does all that ATP come from?
Today, ATP comes from ATP synthases, molecular machines made of protein that are as universal among cells as the genetic code. ATP synthases conserve energy by converting ion gradients into rotary motion to forge ATP out of adenosine diphosphate (ADP) and phosphate. They are ancient, but they cannot be the first source of ATP.
There had to be simpler precursors. Professor William Martin, head of the Institute of Molecular Evolution at HHU and senior author of the study, says, "ATP synthases are complex and evolutionarily advanced molecules. They cannot be the starting point of energy conservation at the origin of life.
Furthermore, phosphate is poorly soluble in the environment and is a very stable molecule that is generally inert. It does not want to react." Manon Schlikker, lead author of the study, says, "But even the simplest forms of metabolism require phosphate as an energy currency. We looked to the environment and microbes for clues.
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