High-yielding and selective prebiotic syntheses of RNA and DNA nucleotides involve UV irradiation to promote the key reaction steps and eradicate biologically irrelevant isomers. While these syntheses were likely enabled by UV-rich prebiotic environment, UV-induced formation of photodamages in polymeric nucleic acids, such as cyclobutane pyrimidine dimers (CPDs), remains the key unresolved issue for the origins of RNA and DNA on Earth. Here, we demonstrate that substitution of adenine with 2,6-diaminopurine enables repair of CPDs with yields reaching 92%. This substantial self-repairing activity originates from excellent electron donating properties of 2,6-diaminopurine in nucleic acid strands. We also show that the deoxyribonucleosides of 2,6-diaminopurine and adenine can be formed under the same prebiotic conditions. Considering that 2,6-diaminopurine was previously shown to increase the rate of nonenzymatic RNA replication, this nucleobase could have played critical roles in the formation of functional and photostable RNA/DNA oligomers in UV-rich prebiotic environments.

• MeSH
• 2-Aminopurine analogs & derivatives   pharmacology   MeSH
• Adenine MeSH
• DNA drug effects   radiation effects   MeSH
• Nucleotides MeSH
• Nucleic Acids MeSH
• DNA Repair drug effects   MeSH
• Pyrimidine Dimers MeSH
• RNA chemistry   MeSH
• Molecular Dynamics Simulation MeSH
• Ultraviolet Rays adverse effects   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• 2-Aminopurine MeSH
• 2,6-diaminopurine MeSH Browser
• Adenine MeSH
• DNA MeSH
• Nucleotides MeSH
• Nucleic Acids MeSH
• Pyrimidine Dimers MeSH
• RNA MeSH

Molecular Darwinian evolution is an intrinsic property of reacting pools of molecules resulting in the adaptation of the system to changing conditions. It has no a priori aim. From the point of view of the origin of life, Darwinian selection behavior, when spontaneously emerging in the ensembles of molecules composing prebiotic pools, initiates subsequent evolution of increasingly complex and innovative chemical information. On the conservation side, it is a posteriori observed that numerous biological processes are based on prebiotically promptly made compounds, as proposed by the concept of Chemomimesis. Molecular Darwinian evolution and Chemomimesis are principles acting in balanced cooperation in the frame of Systems Chemistry. The one-pot synthesis of nucleosides in radical chemistry conditions is possibly a telling example of the operation of these principles. Other indications of similar cases of molecular evolution can be found among biogenic processes.

• Keywords
• Chemomimesis, Molecular Darwinism, origin of life, systems chemistry,
• Publication type
• Journal Article MeSH
• Review MeSH

The molecules of life were created by a continuous physicochemical process on an early Earth. In this hadean environment, chemical transformations were driven by fluctuations of the naturally given physical parameters established for example by wet-dry cycles. These conditions might have allowed for the formation of (self)-replicating RNA as the fundamental biopolymer during chemical evolution. The question of how a complex multistep chemical synthesis of RNA building blocks was possible in such an environment remains unanswered. Here we report that geothermal fields could provide the right setup for establishing wet-dry cycles that allow for the synthesis of RNA nucleosides by continuous synthesis. Our model provides both the canonical and many ubiquitous non-canonical purine nucleosides in parallel by simple changes of physical parameters such as temperature, pH and concentration. The data show that modified nucleosides were potentially formed as competitor molecules. They could in this sense be considered as molecular fossils.

• MeSH
• Biopolymers chemistry   MeSH
• Models, Chemical MeSH
• Evolution, Chemical MeSH
• Molecular Structure MeSH
• Nucleosides chemistry   MeSH
• Origin of Life MeSH
• RNA chemistry   MeSH
• Water chemistry   MeSH
• Earth, Planet MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Biopolymers MeSH
• Nucleosides MeSH
• RNA MeSH
• Water MeSH