RSC School Seminar - Dr. Nick Green (University of Otago)

Title: DNA, RNA and Dehydroalanine: Synthetic Evidence Supporting Prebiological Origins

Abstract

The advent of life requires several ‘key ingredients’ – the identity of these, potential routes to their prebiological synthesis, and a study of their properties that lead to biological behaviours is the domain of prebiotic chemistry.

A polymer suited to information storage and replication is central to any hypothesis explaining life’s origin. The common RNA world hypothesis invokes RNA as this polymer, but other evidence implies that life may have started with a heterogeneous nucleic acid genetic system, including both RNA and DNA. Such a theory streamlines the eventual ‘genetic takeover’ of homogeneous DNA from RNA as the principal information storage molecule in the central dogma of biology, but requires a selective abiotic synthesis of both RNA and DNA building blocks in the same primordial locale. Herein I will discuss an efficient and selective prebiotic synthesis of DNA molecules, alongside those of RNA. The prebiotic reaction uniting these two biomolecules is a photoreduction proceeding with remarkable selectivity, supporting the notion that purine deoxyribonucleosides and pyrimidine ribonucleosides may have coexisted before the emergence of life and the enzymes that now perform this transformation.

Amino acids are also central to the development of sophisticated, organised and functional chemical behaviours that we recognise as biological. I will also discuss recent chemical discoveries implicating formamide as an essential component of the prebiotic milieu, because of its role in the synthesis of dehydroalanine and other amino acid derivatives, which may have a played a critical supporting role to nucleic acids in the rise of biology.