Issue 35, 2016

Life in the light: nucleic acid photoproperties as a legacy of chemical evolution

Abstract

Photophysical investigations of the canonical nucleobases that make up DNA and RNA during the past 15 years have revealed that excited states formed by the absorption of UV radiation decay with subpicosecond lifetimes (i.e., <10−12 s). Ultrashort lifetimes are a general property of absorbing sunscreen molecules, suggesting that the nucleobases are molecular survivors of a harsh UV environment. Encoding the genome using photostable building blocks is an elegant solution to the threat of photochemical damage. Ultrafast excited-state deactivation strongly supports the hypothesis that UV radiation played a major role in shaping molecular inventories on the early Earth before the emergence of life and the subsequent development of a protective ozone shield. Here, we review the general physical and chemical principles that underlie the photostability, or “UV hardiness”, of modern nucleic acids and discuss the possible implications of these findings for prebiotic chemical evolution. In RNA and DNA strands, much longer-lived excited states are observed, which at first glance appear to increase the risk of photochemistry. It is proposed that the dramatically different photoproperties that emerge from assemblies of photostable building blocks may explain the transition from a world of molecular survival to a world in which energy-rich excited electronic states were eventually tamed for biological purposes such as energy transduction, signaling, and repair of the genetic machinery.

Graphical abstract: Life in the light: nucleic acid photoproperties as a legacy of chemical evolution

Article information

Article type
Paper
Submitted
17 iyn 2016
Accepted
11 avq 2016
First published
11 avq 2016

Phys. Chem. Chem. Phys., 2016,18, 24228-24238

Life in the light: nucleic acid photoproperties as a legacy of chemical evolution

A. A. Beckstead, Y. Zhang, M. S. de Vries and B. Kohler, Phys. Chem. Chem. Phys., 2016, 18, 24228 DOI: 10.1039/C6CP04230A

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