Hydrogen peroxide thermochemical oscillator as driver for primordial RNA replication

Abstract

This paper presents and tests a previously unrecognized mechanism for driving a replicating molecular system on the prebiotic earth. It is proposed that cell-free RNA replication in the primordial soup may have been driven by self-sustained oscillatory thermochemical reactions. To test this hypothesis, a well-characterized hydrogen peroxide oscillator was chosen as the driver and complementary RNA strands with known association and melting kinetics were used as the substrate. An open flow system model for the self-consistent, coupled evolution of the temperature and concentrations in a simple autocatalytic scheme is solved numerically, and it is shown that thermochemical cycling drives replication of the RNA strands. For the (justifiably realistic) values of parameters chosen for the simulated example system, the mean amount of replicant produced at steady state is 6.56 times the input amount, given a constant supply of substrate species. The spontaneous onset of sustained thermochemical oscillations via slowly drifting parameters is demonstrated, and a scheme is given for prebiotic production of complementary RNA strands on rock surfaces.

Keywords: RNA world; prebiotic replication; thermochemical oscillator.

Figure 1.

The quadruplex RNA species Z. The duplex replicator species are XY and xy, which for the purposes of the simulation are equivalent. See [3] for more details. (Online version in colour.)

Figure 2.

Computed data from equations (2.1)–(2.3): (a) Hopf (solid line) and saddle-node (dashed line) bifurcation loci; (b) time series for T_f = 282 K, L = 2.4 mW; the oscillation period is 108.7 s. (Online version in colour.)

Figure 3.

Time series from equations (2.1), (2.2) and (2.4)–(2.7) for T_f = 282 K, L = 2.3 mW; period of the oscillation is 99.3 s. (Online version in colour.)

Figure 4.

Onset of oscillations via slow drift of parameters. (a) p ≡ c_w,f, (b) p ≡ T_a, (c) p ≡ F, (d) both p₁ ≡ c_w,f and p₂ ≡ T_a. (Online version in colour.)

Figure 5.

Scheme for supply of template oligomers. The surface-bound single polynucleotide strands S-X and S-Y bind n complementary nucleotide fragments N and N ′ from solution, which are ligated irreversibly to form S-XY and S-YX. Heating promotes release of free X and Y and slower release of duplex XY from S, and melting of free XY to X and Y. The free species can participate in the duplex replication scheme (R 2) and (R 3).