Structured sequences emerge from random pool when replicated by templated ligation

Kudella, Patrick W.; Tkachenko, Alexei V.; Salditt, Annalena; Maslov, Sergei und Braun, Dieter (2021): Structured sequences emerge from random pool when replicated by templated ligation. In: Proceedings of the National Academy of Sciences (PNAS), Bd. 118, Nr. 8, e2018830118

Abstract

The central question in the origin of life is to understand how structure can emerge from randomness. The Eigen theory of replication states for sequences that are copied one base at a time, the replication fidelity has to surpass an error threshold to avoid that replicated specific sequences become random due to the incorporated replication errors [M. Eigen, Naturwissenschaften 58(10), 465-523 (1971)]. Here we showed that linking short oligomers from a random sequence pool in a templated ligation reaction reduced the sequences space of product strands. We started from 12mer oligonucleotides with two bases in all possible combinations and triggered enzymatic ligation under temperature cycles. Surprisingly, we found the robust creation of long, highly structured sequences with low entropy. At the ligation site, omplementary and alternating sequence patterns developed. However, between the ligation sites, we found either an A-rich or a T-rich sequence within a single oligonucleotide. Our modeling suggests that avoidance of hairpins was the likely cause for these two complementary sequence pools. What emerged was a network of complementary sequences that acted both as templates and substrates of the reaction. This autocatalytic ligation reaction could be restarted by only a few majority sequences. The findings showed that replication by random templated ligation from a random sequence input will lead to a highly structured, long and non-random sequence pool. This is a favorable starting point for a subsequent Darwinian evolution searching for higher catalytic functions in an RNA world scenario.

• Dokumententyp: Zeitschriftenartikel
• EU Funded Grant Agreement Number: 787356
• EU-Projekte: Horizon 2020 > ERC Grants > ERC Advanced Grant > ERC Grant 787356: EvoTrap - Mechanisms to emerge and replicate the first sequence information of life in geothermal microfluidics of early Earth
• Fakultät: Physik
• Fakultätsübergreifende Einrichtungen: Center for NanoScience (CENS)
• Themengebiete: 500 Naturwissenschaften und Mathematik > 530 Physik
• Sprache: Englisch