Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA02138, USA.
Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA02114, USA.
Nucleic Acids Res. 2023 Jul 21;51(13):6528-6539. doi: 10.1093/nar/gkad439.
The nonenzymatic copying of RNA is thought to have been necessary for the transition between prebiotic chemistry and ribozyme-catalyzed RNA replication in the RNA World. We have previously shown that a potentially prebiotic nucleotide activation pathway based on phospho-Passerini chemistry can lead to the efficient synthesis of 2-aminoimidazole activated mononucleotides when carried out under freeze-thaw cycling conditions. Such activated nucleotides react with each other to form 5'-5' 2-aminoimidazolium bridged dinucleotides, enabling template-directed primer extension to occur within the same reaction mixture. However, mononucleotides linked to oligonucleotides by a 5'-5' 2-aminoimidazolium bridge are superior substrates for nonenzymatic primer extension; their higher intrinsic reactivity and their higher template affinity enable faster template copying at lower substrate concentrations. Here we show that eutectic phase phospho-Passerini chemistry efficiently activates short oligonucleotides and promotes the formation of monomer-bridged-oligonucleotide species during freeze-thaw cycles. We then demonstrate that in-situ generated monomer-bridged-oligonucleotides lead to efficient nonenzymatic template copying in the same reaction mixture. Our demonstration that multiple steps in the pathway from activation chemistry to RNA copying can occur together in a single complex environment simplifies this aspect of the origin of life.
非酶促 RNA 复制被认为是前生物化学和核酶催化的 RNA 复制之间的过渡所必需的，在 RNA 世界中。我们之前已经表明，基于磷酸 - Passerini 化学的潜在前生物核苷酸激活途径可以在冻融循环条件下进行时，有效地合成 2-氨基咪唑激活的单核苷酸。这样的激活核苷酸彼此反应形成 5'-5' 2-氨基咪唑鎓桥接二核苷酸，使得在同一反应混合物中可以发生模板指导的引物延伸。然而，通过 5'-5' 2-氨基咪唑鎓桥连接到寡核苷酸的单核苷酸是更好的非酶促引物延伸底物；它们更高的固有反应性和更高的模板亲和力使得在较低的底物浓度下更快地复制模板。在这里，我们表明共晶相磷酸 - Passerini 化学有效地激活短寡核苷酸，并在冻融循环期间促进单体桥接寡核苷酸物质的形成。然后，我们证明在相同的反应混合物中，原位生成的单体桥接寡核苷酸导致有效的非酶模板复制。我们的演示表明，从激活化学到 RNA 复制的途径中的多个步骤可以在单个复杂环境中一起发生，简化了生命起源的这一方面。
