RNA-DNA Chimeras in the Context of an RNA World Transition to an RNA/DNA World

• Published in: Angewandte Chemie International Edition Vol. 55; no. 42; pp. 13204 - 13209
• Main Authors: Gavette, Jesse V., Stoop, Matthias, Hud, Nicholas V., Krishnamurthy, Ramanarayanan
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Publishing Ltd 10-10-2016; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: Backbone; Biological evolution; chemical evolution; Chimeras; Clutter; Deoxyribonucleic acid; Deoxyribonucleotides; DNA; Gene sequencing; heterogeneity; homogeneity; Inventions; Nucleotide sequence; Proteins; Ribonucleic acid; RNA; RNA world; Separation; DNA; heterogeneity; RNA world; chemical evolution; homogeneity
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201607919

The RNA world hypothesis posits that DNA and proteins were later inventions of early life, or the chemistry that gave rise to life. Most scenarios put forth for the emergence of DNA assume a clean separation of RNA and DNA polymer, and a smooth transition between RNA and DNA. However, based on the reality of “clutter” and lack of sophisticated separation/discrimination mechanisms in a protobiological (and/or prebiological) world, heterogeneous RNA–DNA backbone containing chimeric sequences could have been common—and have not been fully considered in models transitioning from an RNA world to an RNA–DNA world. Herein we show that there is a significant decrease in Watson–Crick duplex stability of the heterogeneous backbone chimeric duplexes that would impede base‐pair mediated interactions (and functions). These results point to the difficulties for the transition from one homogeneous system (RNA) to another (RNA/DNA) in an RNA world with a heterogeneous mixture of ribo‐ and deoxyribonucleotides and sequences, while suggesting an alternative scenario of prebiological accumulation and co‐evolution of homogeneous systems (RNA and DNA).
Separately together: Heterogeneous RNA/DNA hybrids pose a significant challenge for the homogeneous RNA world to RNA/DNA/Protein world transition model. An alternative scenario of prebiological accumulation and co‐evolution of homogeneous systems (RNA and DNA) is suggested.