On the origin of genomes and cells within inorganic compartments

Abstract

Building on the model of Russell and Hall for the emergence of life at a warm submarine hydrothermal vent, we suggest that, within a hydrothermally formed system of contiguous iron-sulfide (FeS) compartments, populations of virus-like RNA molecules, which eventually encoded one or a few proteins each, became the agents of both variation and selection. The initial darwinian selection was for molecular self-replication. Combinatorial sorting of genetic elements among compartments would have resulted in preferred proliferation and selection of increasingly complex molecular ensembles--those compartment contents that achieved replication advantages. The last universal common ancestor (LUCA) we propose was not free-living but an inorganically housed assemblage of expressed and replicable genetic elements. The evolution of the enzymatic systems for (i) DNA replication; and (ii) membrane and cell wall biosynthesis, enabled independent escape of the first archaebacterial and eubacterial cells from their hydrothermal hatchery, within which the LUCA itself remained confined.

The Origin of Life: Chemical Evolution of a Metabolic System in a Mineral Honeycomb?

“…The replicase replicator (R) aspecifically helps the replication of all types of replicators (dashed-dotted arrows); the membrane-producing replicator T converts metabolic wastes into membrane units (double-headed arrow); d The complete proto-cell capable of life independent of the mineral honeycomb ''prebiotic takeoff'' scenario of metabolic system evolution remains yet to be studied. Our main result in this paper is the support for the importance in prebiotic evolution of inorganic compartments (Koonin and Martin 2005).…”

“…Similarly, other authors ascribe a critical role to the 3D porous structure of iron monosulphide precipitates or aragonite (CaCO 3 ) in hydrothermal vent systems (Koonin and Martin 2005;Martin and Russell 2003;Martin and Russell 2007). Recently, the extreme accumulation of nucleotides in simulated hydrothermal pore systems driven by thermodiffusion has been shown.…”

Extreme accumulation of nucleotides in simulated hydrothermal pore systems

“…For the evolution of life, an already existing protobiological dissipative environment is required (14). The most compelling would refer to an accumulation of molecules into preexisting abundant compartments of cellular dimensions (15). Both requirements are fulfilled by the accumulation mechanism we propose here.…”

5. Prebiotic Chemistry – Biochemistry – Emergence of Life (4.4–2 Ga)

“…Thus, some authors that support the idea of a long acellular evolution during this RNA world period have hypothesized that viruses appeared before cells. Viruses would have been ''hosted'' primarily by a primitive semi-liquid soup or by mineral ''cells'' (Koonin and Martin, 2005). This idea is criticized by other authors favouring the idea that, on the contrary, free cells surrounded by a plasma membrane emerged very early.…”