Experiment sheds light on the origin of life, supporting the existence of a ‘thioester world’ before living beings

As his first name suggests, the Belgian biochemist Christian de Duve was raised in a Catholic family, baptized, educated by Jesuits, and married in the Church. However, he gradually lost his faith through a rational process that culminated in 1974, when he won the Nobel Prize in Physiology or Medicine for discovering lysosomes — organelles with digestive functions inside cells.

In 1991, De Duve proposed a hypothesis about the origin of life that did not require any deity: “the thioester world,” a compound containing carbon, oxygen, hydrogen, and sulfur. On that primordial planet, still devoid of life, thioesters would have provided the energy necessary for chemical elements to react and form more complex molecules, such as the first genetic material, RNA.

On Wednesday, six scientists in London announced that they had successfully triggered in their laboratory the reactions that could have occurred in that thioester world. According to Kepa Ruiz Mirazo, a biophysicist and philosopher at the University of the Basque Country, it is “a major breakthrough, perhaps the most significant in recent times” in the study of the origin of life.

The Big Bang, the massive explosion that gave rise to the universe, occurred about 13.8 billion years ago. The Earth formed roughly 4.5 billion years ago. Very early on, large bodies of water interacted with the planet’s minerals, forming increasingly complex molecules.

The same London laboratory, led by chemist Matthew Powner, 44, already demonstrated in 2019 that with ingredients present on Earth around 4 billion years ago — such as hydrogen sulfide (composed of hydrogen and sulfur) and ferricyanide (carbon, nitrogen, and iron) — peptides could form. These are short versions of proteins, the molecules responsible for the essential functions of life.

Powner’s group at University College London has now taken it a step further. All living beings have DNA, a molecule that functions like a cookbook, containing the recipes to make proteins, such as hemoglobin in the blood, collagen in cartilage, and antibodies that fight pathogens. Another molecule, RNA, reads the information in DNA and carries it to the protein-making factory, called the ribosome. With those instructions, the cellular machinery combines the 20 protein components — amino acids — to produce the required proteins.

Powner’s team has now managed to make amino acids and RNA spontaneously join in their laboratory, in water with a neutral pH, neither acidic nor alkaline, under conditions similar to those that would have existed in some corners of primordial Earth roughly 4 billion years ago. Their results were published Wednesday in Nature, a leading international science journal.

“Life relies on the ability to synthesize proteins — they are life’s key functional molecules. Understanding the origin of protein synthesis is fundamental to understanding where life came from,” Powner said in a statement. “Our study is a big step towards this goal, showing how RNA might have first come to control protein synthesis.”

Powner was in the English valley of Wensleydale, whose name derives from Woden’s Ley, the meadow of Woden or Odin, a once worshiped and now largely forgotten Norse god. Biochemist Christian de Duve, father of the thioester world theory, reflected on gods at age 94, two years before his death.

“The logic of the creator God is an anthropomorphic vision. If I see an object, someone must have made it,” he stated in an interview published in the French weekly Le Point in 2011. “I see the universe, so there must be a creator. But who created the creator God? Theologians respond that God is uncreated. So why would a creator be needed? If I admit the existence of a creator, I inevitably fall into a Russian doll of creators. The universe is uncreated, it exists.”

In the new study, the thioester provides the energy needed for amino acids to activate and bind to RNA, a molecule capable of self-replication. The RNA world hypothesis, proposed by U.S. biologist Alexander Rich in 1962, posits that this versatile molecule was the first hereditary genetic information in early living organisms.

“Our study unites two prominent origin-of-life-theories—the ‘RNA world,’ where self-replicating RNA is proposed to be fundamental, and the ‘thioester world,’ in which thioesters are seen as the energy source for the earliest forms of life,” said Powner in the statement.

Last year, his team managed to synthesize pantetheine, an active fragment of coenzyme A, involved in numerous metabolic processes essential for obtaining energy. The researchers achieved the synthesis in the laboratory, in water at room temperature, from hydrogen cyanide, which was likely abundant on primitive Earth. In the new study, amino acids react with pantetheine.

Biophysicist Kepa Ruiz Mirazo, who did not participate in the study, praises the new work. “This team of researchers has not only achieved peptide synthesis with the participation of RNA molecules, in a manner analogous to but much simpler than that of living cells, but they have also managed to do so under neutral aqueous conditions and using a form of energy activation that is highly plausible for the first steps of life on Earth,” he says.

In Ruiz Mirazo’s opinion, “this is a beautiful demonstration of prebiotic systems chemistry,” the approach that posits that three factors combined in the first living beings: replication, with heritable information; metabolism, with reactions to utilize available energy and matter; and compartmentalization, with encapsulation that creates a protocellular environment. He adds: “There are still many pieces to be solved in the immense puzzle of the origin of life on our planet, but science has found a very important place to fit.”

Sign up for our weekly newsletter to get more English-language news coverage from EL PAÍS USA Edition