Freeze–thaw cycles as drivers of complex ribozyme assembly


The emergence of an RNA catalyst capable of self-replication is considered a key transition in the origin of life. However, how such replicase ribozymes emerged from the pools of short RNA oligomers arising from prebiotic chemistry and non-enzymatic replication is unclear. Here we show that RNA polymerase ribozymes can assemble from simple catalytic networks of RNA oligomers no longer than 30 nucleotides. The entropically disfavoured assembly reaction is driven by iterative freeze–thaw cycles, even in the absence of external activation chemistry. The steep temperature and concentration gradients of such cycles result in an RNA chaperone effect that enhances the otherwise only partially realized catalytic potential of the RNA oligomer pool by an order of magnitude. Our work outlines how cyclic physicochemical processes could have driven an expansion of RNA compositional and phenotypic complexity from simple oligomer pools.

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Figure 1: The hairpin ribozyme and RPR4.
Figure 2: Freeze-thaw cycling drives RPR4 assembly.
Figure 3: Effect of freezing and thawing on RNA and 3frHPz dynamics.
Figure 4: RPR4 assembly intermediate pathways and emergence of polymerase activity.
Figure 5: Assembly of a polymerase ribozyme from fragments ≤30 nucleotides.
Figure 6: Assembly of RPR4 from oligonucleotides devoid of >p preactivation.


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The authors thank J. Attwater for discussions and comments on the manuscript. This work was supported by a Federation of European Biochemical Societies (FEBS) long-term fellowship (H.M.) and by the Medical Research Council (A.W. and P.H., program no. U105178804).

Author information

H.M., A.W. and P.H. conceived and designed the experiments. A.W. performed the in-ice invasion of the stem–loop structure (Supplementary Fig. 5). H.M. performed and analysed all the other experiments. All the authors discussed the results, and wrote and commented on the manuscript.

Correspondence to Philipp Holliger.

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Mutschler, H., Wochner, A. & Holliger, P. Freeze–thaw cycles as drivers of complex ribozyme assembly. Nature Chem 7, 502–508 (2015).

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