|Michael J Russell|| at 11:00
Affiliation: California Institute of Technology
Host: Michael Galperin
Why does life start, what does it do, where will it be?
Energised by an ambient protonmotive force, life is forced into being to hydrogenate carbon dioxide of volcanic derivation on any wet rocky planet of sufficient mass to support mantle convection and hold a CO2/N2 atmosphere (Nitschke & Russell, 2009). The hatchery of life is a compartmentalized submarine hydrothermal mound comprising silica and clay precipitates interspersed with transition metal sulfide clusters and phosphate/pyrophosphate (Russell & Martin, 2004) (Figure). The metal sulfides act as hydrogenation, reduction, transfer and assembly catalysts, while the pyrophosphate acts as a simple polymerase. The phosphate is recharged to pyrophosphate by the proton gradient acting across the inorganic compartment walls separating the carbonic (pH 5-6) oceans from the alkaline (pH 10-12) hydrothermal (~100C) solutions exhaling from the ocean floor. Triphosphates phosphorylate amino acids to form cyclic acylphosphoramidates that react with further amino acids to produce dipeptides. The dipeptides then react with such cyclic acylphosphoramidates to generate tripeptides and so on, forming higher oligopeptides (Milner-White & Russell, 2010). Heterochiral oligopeptides bind to, and stabilize the pyrophosphate and metal sulfide complexes with the overall effect of quickening the hydrogenation of CO2. Once the metabolic engine is running, biosynthesizing and producing effluent of acetate or CH4, then virus-like self-replicating RNAs infect contiguous compartments and encode the proteins that usher in Darwinian evolution (Koonin & Martin, 2005)—synthesizing enzymes that constitute a critical and irreversible improvement on the random associations between the peptide “nests” and their inorganic “eggs”. Proteins also play a part in the organic takeover from the inorganic cell walls—all vital steps for the eventual escape of the first microbes from the mound.
Koonin E, Martin W (2005), On the origin of genomes and cells within inorganic compartments. TiGS 21, 647-654.
Milner-White EJ, Russell MJ (2010), Polyphosphate-peptide synergy and the organic takeover at the emergence of life. Journal of Cosmology, 10, in press.
Nitschke W, Russell MJ (2009), Hydrothermal focusing of chemical and chemiosmotic energy, supported by delivery of catalytic Fe, Ni, Mo/W, Co, S and Se, forced life to emerge. JME 69, 481-496.
Russell MJ, Martin W (2004), The rocky roots of the acetyl coenzyme-A pathway. TiBS 24, 358-363.