EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, UK.
Institute of Physics, Polish Academy of Sciences, Warsaw, Poland.
Nat Commun. 2021 May 21;12(1):3018. doi: 10.1038/s41467-021-23300-y.
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.
高效且选择性的 RNA 和 DNA 核苷酸前体合成涉及紫外线照射以促进关键反应步骤并消除生物学上无关的异构体。虽然这些合成可能是由富含紫外线的前生物环境促成的，但聚合核酸（如环丁烷嘧啶二聚体 (CPD)）中紫外线诱导的光损伤形成仍然是地球上 RNA 和 DNA 起源的关键未解决问题。在这里，我们证明用 2,6-二氨基嘌呤替代腺嘌呤可以实现 CPD 的修复，产率高达 92%。这种大量的自我修复活性源自核酸链中 2,6-二氨基嘌呤优异的供电子特性。我们还表明，2,6-二氨基嘌呤和腺嘌呤的脱氧核苷可以在相同的前生物条件下形成。考虑到 2,6-二氨基嘌呤先前被证明可以提高非酶 RNA 复制的速度，这种碱基在前生物富含紫外线的环境中形成具有功能和光稳定性的 RNA/DNA 寡聚物方面可能发挥了关键作用。
