American researchers have discovered processes essential to the appearance of life on Earth by observing ancient proteins.
- Scientists are still struggling to precisely explain the appearance of life on Earth.
- New research shows that 20 specific amino acids could explain the development of proteins, and therefore of life.
- It could also bring new lines of research concerning life on other planets.
There is still a lot of mystery surrounding the appearance of life on Earth. In the United States, a research team has taken a step further in understanding this phenomenon. In the magazine Journal of the American Chemical Societyscientists from Johns-Hopkins University explain how analyzing an ancient protein has given them a better understanding of the role of certain amino acids in the appearance of life on our planet.
Life on Earth: a laboratory experiment to understand evolution
In an experiment carried out in the laboratory, they simulated the first conditions of life on Earth. They thus discovered that, without specific amino acids, proteins could not have evolved and become living beings, such as humans, animals or plants. “You see the same amino acids in every organism, from humans to bacteria to archaea.”, says Stephen Fried, a chemist at Johns Hopkins University who co-led the research with scientists at Charles University in the Czech Republic. Archaea are microorganisms, without a nucleus in their cell, which live in hostile environments, such as water laden with salt. “This is because all things on Earth are connected through this tree of life, which has an origin: an organism that was the ancestor of all living things.“, he develops. In their study, they set out the characteristics of this common ancestor: it had specific amino acids.
Specific amino acids contributed to the development of life on Earth
In the laboratory, the researchers imitated the synthesis of so-called primordial proteins, those present 4 billion years ago. To achieve this, they used a set of amino acids, very abundant before the appearance of life on Earth. In a communicatedthey explain having discovered that “ancient organic compounds incorporated the amino acids best suited to the deployment of proteins in their biochemistry”. In other words, the development of life on the planet is linked to the fact that certain amino acids were particularly effective in helping proteins take on specific shapes to perform certain functions. “You could have evolution before you had biology, you could have natural selection for chemicals that are useful for life even before there was DNA.”, observes Stephen Fried. According to him, 20 main amino acids have contributed to the appearance of life on earth, without knowing exactly what is specific about them in comparison to the others.
Amino acids and life on Earth: how to explain their appearance?
The chemist adds that certain amino acids were present from the beginning of the Earth’s atmosphere. “Others arrived by meteorite, which introduced a set of ingredients that helped the appearance of life on Earth“, he adds. Scientists have also identified amino acids in asteroids far from Earth, which suggests that these compounds are ubiquitous in other places in the universe. For Stephen Fried, this research could thus provide new avenues of research regarding the possibility of finding life beyond Earth.