Institut für Organische Chemie, Universität Stuttgart, 70569, Stuttgart, Germany.
Angew Chem Int Ed Engl. 2018 Jul 16;57(29):8911-8915. doi: 10.1002/anie.201803074. Epub 2018 Jun 19.
All known forms of life encode their genetic information in a sequence of bases of a genetic polymer and produce copies through replication. How this process started before polymerase enzymes had evolved is unclear. Enzyme-free copying of short stretches of DNA or RNA has been demonstrated using activated nucleotides, but not replication. We have developed a method for enzyme-free replication. It involves extension with reversible termination, enzyme-free ligation, and strand capture. We monitored nucleotide incorporation for a full helical turn of DNA, during both a first and a second round of copying, by using mass spectrometry. With all four bases (A/C/G/T), an "error catastrophe" occurred, with the correct sequence being "overwhelmed" by incorrect ones. When only C and G were used, approximately half of the daughter strands had the mass of the correct sequence after 20 copying steps. We conclude that enzyme-free replication is more likely to be successful with just the two strongly pairing bases than with all four bases of the genetic alphabet.
所有已知形式的生命都将其遗传信息编码在遗传聚合物的碱基序列中，并通过复制产生副本。在聚合酶出现之前，这个过程是如何开始的还不清楚。已经证明，使用激活的核苷酸可以在没有酶的情况下复制短链的 DNA 或 RNA，但不能进行复制。我们已经开发出一种无酶复制的方法。它涉及使用可逆终止的延伸、无酶连接和链捕获。我们通过质谱法监测了 DNA 完整螺旋轮次的核苷酸掺入情况，包括第一轮和第二轮复制。使用所有四个碱基（A/C/G/T）时，会发生“错误灾难”，正确序列会被错误序列“淹没”。当仅使用 C 和 G 时，在 20 次复制步骤后，大约有一半的子链具有正确序列的质量。我们的结论是，与遗传字母的四个碱基相比，只用两个强配对碱基进行无酶复制更有可能成功。
