RNA is a crucial biological molecule that plays a key role in the genetics of organisms and the evolution of life. The way RNA molecule folds in on itself is determined by its spatial conformation and composition, which is quite similar to DNA. A recent study published in the journal Proceedings of the National Academy of Sciences sheds light on how the process of RNA folding at low temperatures may open up a novel perspective on primordial biochemistry and the evolution of life on Earth.
The study, led by Professor Fèlix Ritort from the University of Barcelona, revealed that RNA sequences forming hairpin structures begin to adopt new, compact structures below 20°C. The team identified a range of temperatures between +20°C and -50°C, where RNA stability is modulated by ribose-water interactions. The formation of hydrogen bonds between ribose and water plays a significant role in creating unexpected novel structures at low temperatures. This phenomenon, known as cold denaturation, is unique to RNA and not observed in DNA.
The findings of this study have significant implications for the biochemistry and biological functions of RNA. The dominance of ribose-water interactions alters the known rules that stabilize RNA biochemistry by A-U and G-C pairing and base-to-base stacking forces. This altered biochemistry, defined as the sweet-RNA world, suggests the existence of a primitive, coarse biochemistry based on ribose and other sugars that predates RNA itself. The sweet-RNA world possibly began to evolve in cold environments in outer space, subject to thermal cycles of heat and cold.
To reach their conclusions, the research team utilized the technique of optical tweezer force spectroscopy to measure molecular thermodynamics. This precise technique allowed them to detect a decrease in the heat capacity of the folded RNA around 20°C, indicating a reduction in the number of degrees of freedom of the folded RNA due to ribose-water bonds. The team also measured entropy changes and heat capacity during the folding of RNA, providing valuable insights into the RNA folding process.
The altered biochemistry determined by ribose-water interactions has implications for organisms that inhabit cold regions of the Earth, such as psychrophiles. These organisms thrive in environments below 10°C, including alpine regions, deep waters of the oceans, and arctic territories. The new RNA biochemistry based on ribose-water interactions challenges the conventional pairing rules of A-U and G-C, offering a new perspective on the evolution of life in cold environments.
The study on RNA folding at low temperatures unveils novel structures and biochemistry that have potential implications for the origins and evolution of life on Earth. The sweet-RNA world concept introduced by Professor Fèlix Ritort suggests a primitive biochemistry based on ribose and sugars that predates the evolution of RNA. Further research in this field may provide valuable insights into the role of RNA in the development and adaptation of life forms in extreme environments.
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