Emergence of native peptide sequences in prebiotic replication networks

Jayanta Nanda,Yair Motro,Rivka Cohen-Luria,Yifat Miller,Elina Shtelman,Nathaniel Wagner,Rakesh Mukherjee,Boris Rubinov,Denis Ivnitski,Gonen Ashkenasy

doi:10.1038/s41467-017-00463-1

Abstract

Biopolymer syntheses in living cells are perfected by an elaborate error correction machinery, which was not applicable during polymerization on early Earth. Scientists are consequently striving to identify mechanisms by which functional polymers were selected and further amplified from complex prebiotic mixtures. Here we show the instrumental role of non-enzymatic replication in the enrichment of certain product(s). To this end, we analyzed a complex web of reactions in β-sheet peptide networks, focusing on the formation of specific intermediate compounds and template-assisted replication. Remarkably, we find that the formation of several products in a mixture is not critically harmful, since efficient and selective template-assisted reactions serve as a backbone correction mechanism, namely, for keeping the concentration of the peptide containing the native backbone equal to, or even higher than, the concentrations of the other products. We suggest that these findings may shed light on molecular evolution processes that led to current biology.

Highlights

Biopolymer syntheses in living cells are perfected by an elaborate error correction machinery, which was not applicable during polymerization on early Earth
This study focuses on the unique non-enzymatic replication that takes place in a small network made up of peptide 2 and its isomers (Fig. 2)
Ill-defined protein sequences are doomed by the cell machinery to post-synthesis digestion, enriching the population of functional proteins

Summary

Introduction

Biopolymer syntheses in living cells are perfected by an elaborate error correction machinery, which was not applicable during polymerization on early Earth. We find that when the replicating molecule is the condensation kinetic product, modest replication exerted, but when the network reaction is initiated with materials leading primarily to other products with a non-homogenous backbone, efficient correction takes place by replication and enrichment of the native peptide at the expense of other network components.

Results

Conclusion