Prebiotic Chemistry and the Origin of the RNA World

Abstract

The demonstration that ribosomal peptide synthesis is a ribozyme-catalyzed reaction makes it almost certain that there was once an RNA World. The central problem for origin-of-life studies, therefore, is to understand how a protein-free RNA World became established on the primitive Earth. We first review the literature on the prebiotic synthesis of the nucleotides, the nonenzymatic synthesis and copying of polynucleotides, and the selection of ribozyme catalysts of a kind that might have facilitated polynucleotide replication. This leads to a brief outline of the Molecular Biologists' Dream, an optimistic scenario for the origin of the RNA World. In the second part of the review we point out the many unresolved problems presented by the Molecular Biologists' Dream. This in turn leads to a discussion of genetic systems simpler than RNA that might have "invented" RNA. Finally, we review studies of prebiotic membrane formation.

Non‐Enzymatic RNA Backbone Proofreading through Energy‐Dissipative Recycling

“…Recent reports describe the possible abiotic production of monomeric RNA precursors from simple feedstocks,1, 2, 3, 4 but advancing to the next level of complexity has been hindered by several constraints 5, 6, 7. Foremost of these is the inherent lack of regiocontrol in the oligomerization of activated ribonucleotides.…”

“…Foremost of these is the inherent lack of regiocontrol in the oligomerization of activated ribonucleotides. In the absence of complex macromolecular catalysts, new internucleotide linkages are inevitably forged as both 3′,5′‐ and 2′,5′‐phosphodiester bonds 6, 7, 8. The problem has prompted extensive investigation, ranging from synthetic efforts to favor natural 3′,5′‐bonds,8, 9, 10, 11 to the finding that, below a threshold level, backbone heterogeneity might be compatible with the catalytic and recognition properties of RNA 12.…”

Entropy Production and the Origin of Life

“…One hundred years later, inspired by Oparin's 1924 suggestion of a material origin of life [2], Miller and Urey [3] showed that subjecting what was then the best hypothesis for the gasses of the prebiotic atmosphere (methane, ammonia, water, and carbon dioxide) to electric discharge was sufficient to produce at least 11 of the 20 then known amino acids making up the proteins of life (actually there are 22 known amino acids of life). Since then, many other similar experiments have demonstrated abiogenic routs to, not only the amino acids, but also to the nucleic acid bases, the ribose-like sugars, and the polyphosphates; the basic constituents of RNA and DNA, the probable first molecules of life [4,5].…”

Spontaneous mirror symmetry breaking and origin of biological homochirality

“…Models of mutualism and cooperative effects in autocatalytic sets, on quasi-species, the protein world and the RNA world (see for example, [3][4][5][6]) all assume tacitly the homochirality of the implied species. The origin of biological homochirality is thus considered as a separate and disjoint event: the formation of enantiomerically pure polymers is assumed to occur by starting from enantiomerically pure mixtures of their monomers.…”