The origin of metabolism during early evolution – the role of microcompartmentalisation
Since the seminal experiments of Miller and Urey in the 1950ies it is assumed that the first biomolecules on earth have been generated through geochemical processes (S.L. Miller, 1953). However, the subsequent series of events that facilitated cells to start a metabolic network, and thus allowed the cells to become independent on geochemical presence of their constituents, are still enigmatic. Conducting a comprehensive chemical simulation of the Archean Ocean, we have recently detected enzyme-free catalytic reactions that resemble reaction structures found in in modern metabolism. Importantly, the spontaneous formation of a chemical reaction network that mimics to a large extend glycolysis and the pentose phosphate pathway (PPP) is detected, indicating that the origin of metabolism has been constrained by the constituents of the environments of the early Archean ocean (Keller et al, in revision).
This PhD should address one unsolved problem the origin of first metabolism: How did life-compatible concentrations of sugar phosphate metabolites (required to form RNA, amino acids act.) have been achieved?. It has been speculate that microcompartments could support the selective enrichment. It is the ideas of this project to replicate plausible protocells, recently shown to facilitate non enzymatic RNA amplification (Adamala and Szostak, Science, 2013), in a simulation of the chemical environment of the Archean ocean. This will be combined with our enzyme-free glycolysis-like reaction network (Keller et al). These conditions will facilitate reaction systems to separate the Archean catalyst from the product, and it should be addressed whether this can be exploited to enrich carbohydrates. The project should further address the impact on non-enzymatic metabolic network structures. Addressing the evolutionary constraints of early metabolism, this project will therefore contribute to the fundamental understanding about the design principles of metabolism, whose structures are underlying the biochemical network of every modern cell.
- Adamala K & Szostak JW (2013) Nonenzymatic template-directed RNA synthesis inside model protocells. Science 342: 1098–100
- Luisi PL (2012) An open question on the origin of life: the first forms of metabolism. Chem. Biodivers. 9: 2635–47
- Keller A, Turchyn AV, and Ralser M, (in revision). Spontaneous assembly of a glycolysis-like reaction network in the plausible primeval ocean