Genetics first or metabolism first? The formamide clue

Abstract

Life is made of the intimate interaction of metabolism and genetics, both built around the chemistry of the most common elements of the Universe (hydrogen, oxygen, nitrogen, and carbon). The transmissible interaction of metabolic and genetic cycles results in the hypercycles of organization and de-organization of chemical information, of living and non-living. The origin-of-life quest has long been split into several attitudes exemplified by the aphorisms "genetics-first" or "metabolism-first". Recently, the opposition between these approaches has been solved by more unitary theoretical and experimental frames taking into account energetic, evolutionary, proto-metabolic and environmental aspects. Nevertheless, a unitary and simple chemical frame is still needed that could afford both the precursors of the synthetic pathways eventually leading to RNA and to the key components of the central metabolic cycles, possibly connected with the synthesis of fatty acids. In order to approach the problem of the origin of life it is therefore reasonable to start from the assumption that both metabolism and genetics had a common origin, shared a common chemical frame, and were embedded under physical-chemical conditions favourable for the onset of both. The singleness of such a prebiotically productive chemical process would partake of Darwinian advantages over more complex fragmentary chemical systems. The prebiotic chemistry of formamide affords in a single and simple physical-chemical frame nucleic bases, acyclonucleosides, nucleotides, biogenic carboxylic acids, sugars, amino sugars, amino acids and condensing agents. Thus, we suggest the possibility that formamide could have jointly provided the main components for the onset of both (pre)genetic and (pre)metabolic processes. As a note of caution, we discuss the fact that these observations only indicate possible solutions at the level of organic substrates, not at the systemic chemical level.

Shedding light on the formation of the pre-biotic molecule formamide with ASAI

“…Formamide (NH2CHO) contains the four most important ele-ments for biological systems: C, H, O, and N, and it has recently been proposed as a pre-biotic precursor of both metabolic and genetic material, suggesting a common chemical origin for the two mechanisms (Saladino et al 2012).…”

Ribozyme Activity of RNA Nonenzymatically Polymerized from 3′,5′-Cyclic GMP

“…The conditions for self-polymerization of cyclic pyrimidine nucleotides have not been determined, yet. Early pioneering approaches are reviewed in [21][22][23]. Efficient enzyme-free copying of all four pre-activated nucleobases, templated by immobilized RNA, was reported [24].…”

Meteorite-catalyzed syntheses of nucleosides and of other prebiotic compounds from formamide under proton irradiation

“…These included montmorillonite [phyllosilicate, (Na,Ca) 0.33 (Al,Mg) 2 Table 2, minerals are overall less efficient than meteorites in the synthesis of nucleobases. In particular, purine nucleobases prevailed on pyrimidines, adenine and guanine being isolated in the reactions with at least three of the minerals studied (montmorillonite, troilite, and magnetite; covellite was completely nonreactive).…”

“…FA (NH 2 CHO) is becoming one of the most intensively studied precursors for prebiotic syntheses of compounds potentially relevant for the origin of life (1)(2)(3)(4). FA is a ubiquitous molecule in the universe.…”

“…DNA and RNA components (15)(16)(17)(18)(19)(20)(21), amino acids (22,23), sugars (24), and carboxylic acids (25,26) have been obtained. Minerals tune the selectivity of these transformations (1,2), the mechanistic pathways for the synthesis of nucleobases requiring pyrimidine (27)(28)(29)(30) or imidazole intermediates (31,32).…”