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 and surprising source of energy that drove primordial chemical reactions on the early Earth forward to kick-start metabolism. Their findings, now published in FEBS Journal , identify phosphite and palladium, compounds that naturally occur in H 2 -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. But what?
Professor William Martin, head of the Institute of Molecular Evolution at HHU and senior author on the study: “ATP-synthases are complex and evolutionarily advanced molecules, they cannot be the starting point of energy conservation at origins. 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 on the study: “But even the simplest forms of metabolism require phosphate as an energy currency, how did that start? We looked to the environment and microbes for clues. Many reactions of metabolism work well without enzymes, using metal catalysts that naturally occur in hydrothermal vents. In addition, many bacteria that inhabit hydrothermal vents solve the phosphate problem with phosphite, which also occurs naturally in vents. We tried that combination in the laboratory and found that some hydrothermal vent metals can activate phosphite to phosphate, and some can even phosphorylate molecules, just like ATP.”
Hydrothermal vents have been around on Earth for as long as there has been liquid water. Some scientists, including Martin and team, think that life arose at hydrothermal vents and that traces of that origin are still preserved in the metabolism of modern cells. “Microbes that use environmental phosphite for growth convert it to phosphate with an enzyme called AdpA,” explains Schlikker. “In that reaction, AdpA phosphorylates adenosine monophosphate (AMP) to adenosine diphosphate (ADP), it conserves the energy in phosphite as a high energy phosphate bond. Since hydrothermal vent metals are good catalysts, I tried using metals to replace the AdpA enzyme – and it worked. Metallic nickel worked but palladium, which also occurs in vents, worked much, much better.”
Replacing enzymes with metals under hydrothermal vent conditions is a recurrent theme in the work of the HHU team. “For the past ten years, we have been investigating the ability of metals that naturally occur in hydrothermal vents, such as nickel, iron, and cobalt, to act as catalysts that can replace enzymatic functions,” says Martin. “But to replace enzymes, the metals need to be in their native state: not just some rock, but metals in their shiny, native state, like coins. H 2 -producing hydrothermal vents not only contain phosphite, they naturally deposit the metals in exactly that shiny state.”
That palladium catalysed the phosphorylation of AMP to ADP with phosphite, replacing the AdpA enzyme “was a very exciting result” says Schlikker, “there was no literature at all on anaerobic phosphite oxidation using palladium before our work.” The most common natural form of palladium in H 2 -producing hydrothermal vents is a palladium alloy with nickel and iron. To test if that form is also active, the team of Dr Harun Tüysüz at the Max-Planck-Institut für Kohlenforschung and the IMDEA Foundation in Madrid, specialists for materials science, synthesised the palladium-iron-nickel alloy in the lab. “We were of course very pleased to see that it, too, catalysed the phosphorylation reaction,” says Tüysüz.
Schlikker and colleagues then cast their experimental net more broadly to what else the phosphite/palladium system can phosphorylate. They found that a large number of biologically relevant substrates are readily phosphorylated, including ribose, glucose, glycerol and acetate. Acetate was particularly interesting because acetyl-phosphate has long been considered as a primordial currency of biochemical energy.
“What we see here,” says Martin, “is a novel and geochemically continuous route of prebiotic phosphorylation in water using a substrate and a catalyst, phosphite and palladium, that naturally occur in H 2 -producing hydrothermal vents.” Tüysüz adds: “This geochemical phosphorylating chemistry is much simpler than the enzymatic route, it operates in water and the catalyst has a very broad substrate specificity. It is has all the properties expected of a truly primordial process.”
The energy that drives this phosphorylating reaction forward comes from phosphite itself. “Phosphite is a very energy-rich but very stable compound,” says Martin, “when it reacts to form phosphate it releases more energy than ATP, but it needs a good catalyst to react. Palladium is the most effective inorganic catalyst for phosphite activation we have found so far.”
Is the hydrothermal duo of phosphite and palladium the long sought source of phosphorylation at origins? Martin concludes: “Looking at the matter openly, phosphite plus tiny, catalytic amounts of palladium represent a naturally formed geochemical precursor of ATP. At origins, this newly recognised source of environmental energy could have provided the momentum needed to set the chemical reactions of life in motion.”
Manon L. Schlikker, Nadja K. Hoffmann, Sabine Metzger, Jorge Moral-Pombo, Harun Tüysüz, William F. Martin. Hydrothermal origin of metabolic phosphorylation. FEBS Journal (2026)
DOI: 10.1111/febs.70737
FEBS Journal
Hydrothermal origin of metabolic phosphorylation.
29-Sep-2026