Peptide and RNA contributions to iron–sulphur chemical gardens as life's first inorganic compartments, catalysts, capacitors and condensers

Abstract

Hydrothermal chimneys and compartments comprising transition metal sulphides and associated minerals have been proposed as likely locations for the beginnings of life. In laboratory simulations of off-axis alkaline springs, it is shown that the interaction of a simulated alkaline sulphide-bearing submarine vent solution with a primeval anoxic iron-bearing ocean leads to the formation of chimney structures reminiscent of chemical gardens. These chimneys display periodicity in their deposition and exhibit diverse morphologies and mineralogies, affording the possibilities of catalysis and molecular sequestration. The addition of peptides and RNA to the alkaline solution modifies the elemental stoichiometry of the chimneys-perhaps indicating the very initial stage of the organic takeover on the way to living cells by charged organic polymers potentially synthesized in this same environment.

Green Rust: The Simple Organizing &lsquo;Seed&rsquo; of All Life?&nbsp;&nbsp;<strong> </strong>

“…[93] The trace metals required for catalysis would be precipitated with the sulfides and oxides on meeting the margins of the alkaline vent fluid. [125,147] However, as we have argued, endergonic reactions (a positive DG) can't be made to happen by mere catalysis, which can only reduce an activation energy, so mere catalysis cannot explain the emergence of life. [3,6] We need instead, nanoscale disequilibrium converters situated at the margins of the alkaline hydrothermal mound to take advantage of the various gradients imposed by the precipitation of relatively insoluble inorganic entities.…”

“…[88,180] Nevertheless, without the protection of organic intercalates there is a tendency for the Fe 2+ to dissolve, thereby threatening the integrity of the mineral. [20,125,182] Although these green rust-comprising barriers would have been leaky, individual crystallites would have frustrated immediate dissipation. [28] Green rusts comprising this barrier would be subject to large redox and pH gradients with ranges that had the potential commensurate with that required for the onset of metabolism.…”

“…Notably, these can be produced in the lab with 10 mmol FeII iron concentrations, well below the many tens of mmol of iron in the ~ 400ºC spring sources mentioned above (Figures 1 and 2). [101,124,125] We will also touch on the likely, or possible, accompanying minor minerals, greigite, violarite and tochilinite. But we first consider the implication of a foundational presumption of the AHV theory: that life itself was driven into being by thermodynamic forcesjust as has also been, and by absolute necessity, every living thing since.…”

Physico-chemical interactions between compartment-forming lipids and other prebiotically relevant biomolecules

“…The co-localization of a replicating molecular system within a membranous boundary would lead directly to the emergence of protocells, whereas other scenarios that are considered plausible for the synthesis of nucleic acids such as mineral surfaces [8][9][10], would require additional steps in which polymers are first released from the mineral, followed by encapsulation.…”

The memory of surfaces: epitaxial growth on quasi-crystals

“…In that case, the resulting structure is the atomic BoseEinstein condensate. Alternatively, the information is contained in biological molecules such as DNA [2] or peptides and RNA [3], and a new structure is generated or replicated through biological processes. Another possibility is that the information may be contained within the structural elements or building blocks themselves, and the new structure is generated through a process of Table 1.…”