Ribonucleic acid (RNA) is a fundamental biological molecule that plays a critical role in the genetics of living organisms and is essential in understanding the origin and evolution of life. Much like DNA, RNA is made up of ribose molecules linked to phosphate groups and nitrogenous bases. The spatial conformation of RNA, or the way it folds on itself, dictates its biological functions. Recently, a groundbreaking study led by Professor Félix Ritort from the University of Barcelona sheds light on the fascinating process of RNA folding at low temperatures and its potential implications for the evolution of life on Earth.
The study conducted by Professor Félix Ritort and his team at the UB’s Department of Condensed Matter Physics identified unexpected novel structures of RNA at low temperatures. The research revealed that RNA sequences forming hairpin structures start to adopt new, compact configurations below 20°C. These unique structures are a result of ribose-water interactions that become significant at lower temperatures. Interestingly, RNA stability reaches its peak at +5°C due to the maximal density of water. Below this temperature, ribose-water interactions continue to influence RNA stability until -50°C, leading to the phenomenon of cold denaturation.
The paper suggests that the temperature range affecting RNA folding is universal and applies to all RNA molecules, although it may vary based on the sequence and environmental conditions such as salt concentration and acidity. These new RNA structures are stabilized by the formation of complementary base pairs, specifically adenine binding to uracil (A-U) and guanine binding to cytosine (G-C). The researchers propose that the hydrogen bonds between ribose and water contribute significantly to the stability of these structures, outweighing the interactions between complementary bases in RNA.
The study conducted by Professor Félix Ritort’s team employed optical tweezer force spectroscopy to measure molecular thermodynamics during the folding of various RNAs. The results indicate a decrease in heat capacity of the folded RNA around 20°C, suggesting a reduction in the degrees of freedom due to ribose-water bonds. This discovery challenges the existing rules that govern RNA biochemistry based on A-U and G-C pairing and base-to-base stacking forces. The emergence of a new RNA biochemistry driven by ribose-water interactions could have profound implications for organisms inhabiting cold regions on Earth, known as psychrophiles.
Professor Félix Ritort introduces the concept of a primitive biochemistry called the “sweet-RNA world,” predating the traditional RNA biochemistry that we are familiar with. This primitive biochemistry relies on ribose and other sugars and is speculated to have evolved in cold environments in outer space, potentially on celestial bodies near stars subjected to thermal cycles of heat and cold. The discovery of this altered biochemistry challenges our understanding of RNA functions and opens up a new realm of possibilities for the evolution of life beyond Earth.
The groundbreaking study by Professor Félix Ritort and his team provides valuable insights into the world of RNA folding at low temperatures, uncovering novel structures and biochemical processes that could reshape our understanding of the origins of life on Earth and beyond.