#NCNGeneration– Rafał Szabla: Basic building blocks of life on early Earth
In the 10th episode of the series, we talk to Rafał Szabl, chemist from the Wrocław University of Science and Technology, who studies how simple chemical compounds could have given rise to the basic building blocks of life on the early Earth
Prof. Rafał Szabla, theoretical chemist at the Faculty of Chemistry at Wrocław University of Science and Technology, together with his research team, studies the fundamental properties of RNA, DNA, and other biomolecules, their reactivity, and their interactions with ultraviolet radiation. His research into prebiotic chemistry helps us understand how life emerged on the early Earth.
Chemistry of the early Earth
Around 3.8 billion years ago, when the Late Heavy Bombardment ended, liquid water existed on Earth, some land had already formed and there was an atmosphere with practically no molecular oxygen. Researchers associate this period with the origins of life, although the transition from chemistry to the first living organisms remains unclear. “Life is, above all, chemistry. In all living systems—in cells, even the simplest ones—their function is governed by chemistry. Chemistry determines how they manage energy. Chemistry is also responsible for the way they can divide, that is replicate,” says Rafał Szabla.
In small bodies of water, where chemical compounds could become concentrated and reactions could take place efficiently, hydrogen cyanide played a crucial role. Although toxic today, it may have been a key starting point for the formation of more complex structures. It was the initial building block from which something more complex could emerge.
The emerging life needed energy from somewhere. Today, living organisms derive energy from the sun, but in the beginning, other resources of energy were needed. At this point, the researcher puts forward a tentative hypothesis that sugars might have played a key role, dating back to the period when the planet Earth was forming. This is supported by studies of extraterrestrial material: in asteroid samples and observations of protoplanetary disks, as well as during the Rosetta mission to a comet, apart from simple components of RNA and DNA, protein-building amino acids and sugars were also found.
How do scientists study such a distant past?
Since we cannot go back in time and cannot find fossils dating back billions of years, we should rephrase the question about the origin of life on Earth and ask “How could life have emerged under specific conditions,” that is considering the constraints based on our knowledge of the composition of the atmosphere, the chemical composition of the Earth’s crust, and the conditions that may have existed in small lakes and lagoons.
A groundbreaking moment was a 2009 publication in Nature by John Sutherland, which showed how two of four nucleic acid building blocks could have formed on the early Earth. Ultraviolet radiation played a key role. The same reactions could produce many different products, while ultraviolet radiation favoured the formation of the desired structures. Theoretical chemistry, which is the focus of Rafał Szabla’s research, explains the mechanisms of such reactions through experimentally verified calculations. In collaboration with John Sutherland’s team and co-investigators from the Wrocław University of Science and Technology – prof. Robert Góra and dr Mikołaj Janicki – the researcher explained the mechanisms behind the formation of additional key building blocks of nucleic acids; their paper was published in Nature in 2020. “For me, an extremely fascinating question is how these nucleic acids — RNA or DNA — could have gained their first functionality on the early Earth. For example, how could they have been able to self-replicate.”
Where does basic research take us
Prebiotic chemistry enables us to discover chemical reactions that are completely new, and the knowledge gained paves the way for practical applications, e.g. more efficient DNA replication. Rafał Szabla, however, reminds us that the path from discovery to its application can be long. “Maria Skłodowska-Curie was also driven by curiosity. When she made her first discoveries she could not fully realise how far-reaching their implications would be. Many of these implications were only discovered many, many years later. So without fundamental research, there are no applications — and there will be no applications in the future.”
The #NCNGeneration series consists of 15 conversations with 15 researchers to mark the 15th anniversary of the National Science Centre. Each conversation lasts 15–20 minutes. They are hosted by Anna Korzekwa-Józefowicz.
In earlier episodes, we spoke with Aleksandra Rutkowska, Michał Tomza, Małgorzata Kot, Karolina Ćwiek-Rogalska, Maciej Trusiak, Agata Starosta, Karolina Safarzyńska, Karolina Kremens and Maciej Grzybek. In upcoming episodes, we will hear from Piotr Bystranowski, Artur Obłuski and Monika Wróbel. The episodes are released on NCN’s YouTube channel every third Thursday through the end of the year.
