An experiment sheds light on the origin of life and supports the existence of a “thioester world” prior to living beings.

As his Christian first name suggests, Belgian biochemist Christian de Duve was raised in a Catholic family, baptized, educated by the Jesuits, and married in the Church, but he gradually lost his faith during a rational process that culminated in 1974, when he won the Nobel Prize in Medicine for the discovery of lysosomes, organelles with digestive functions inside cells. In 1991, de Duve proposed a hypothesis about the origin of life without the need for a God: " the thioester world ," a compound of carbon, oxygen, hydrogen, and sulfur. On that primordial planet, still devoid of living beings, thioesters would have provided the energy necessary for chemical elements to react to form more complex molecules, such as the first genetic material, RNA. This Wednesday, six London scientists announced that they have managed to trigger in their laboratory the reactions that could have occurred on that thioester world. It is “a major breakthrough, perhaps the most significant in recent times” in research into the origin of life, according to Kepa Ruiz Mirazo , a biophysicist and philosopher at the University of the Basque Country.

The Big Bang , the great explosion that gave rise to the universe, took place about 13.8 billion years ago. The Earth formed about 4.5 billion years ago. And very early on , large bodies of water were interacting with the planet's minerals, forming increasingly complex molecules. The same London laboratory, headed by chemist Matthew Powner , already demonstrated in 2019 that with ingredients present on Earth about 4 billion years ago, such as hydrogen sulfide (made up of hydrogen and sulfur) and ferricyanide (carbon, nitrogen, and iron), peptides could be formed, a kind of shortened version of proteins, the molecules responsible for the essential functions of life.

Powner's group at University College London has now gone a step further. All living beings have DNA, a molecule that functions like a cookbook, containing recipes for making proteins, such as hemoglobin in the blood, collagen in cartilage, and antibodies that fight pathogens. Another molecule, RNA, reads the information in the DNA and transports it to the protein factory, called the ribosome. With these instructions, the cell factory combines the 20 protein components, called amino acids, and generates the required protein. Powner's team has now managed to get the amino acids and RNA to spontaneously bind in their laboratory, in water with a neutral pH, neither acidic nor alkaline, under conditions similar to those found in some corners of the primitive Earth, some 4 billion years ago. Their results are published this Wednesday in the journal Nature , a leading international scientific journal.

“Life depends on the ability to synthesize proteins: they are the key functional molecules for life. Understanding the origin of protein synthesis is fundamental to understanding where life comes from,” Powner said in a statement. “Our study is a major step toward that goal, showing how RNA could have begun to control protein synthesis.”

Powner was born 44 years ago in the English valley of Wensleydale, whose name derives from Woden's Ley , or Odin's meadow, a once-idolized and now-ignored Norse god. Biochemist Christian de Duve, father of the thioester world theory, reflected on the gods at the age of 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. 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,” he declared in an interview published in the French weekly Le Point in 2011.

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 American 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 theories about the origin of life: the RNA world, which proposes that self-replicating RNA is fundamental, and the thioester world, which views thioesters as the energy source for the earliest life forms,” Powner argues. Last year, his team managed to synthesize pantetheine , an active fragment of coenzyme A, involved in a multitude of metabolic processes essential for obtaining energy. The researchers achieved the synthesis in the laboratory, in water at room temperature, from hydrogen cyanide, probably very abundant on early Earth. In the new study, amino acids react with pantetheine.

Biophysicist Kepa Ruiz Mirazo applauds the new study, in which he did not participate. “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 emphasizes. 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. “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,” the researcher celebrates.