The Divergence and Natural Selection of Autocatalytic Primordial Metabolic Systems

Abstract

The diversity of the central metabolism of modern organisms is caused by the existence of a few metabolic modules, combination of which produces multiple metabolic pathways. This paper analyzes biomimetically reconstructed coupled autocatalytic cycles as the basis of ancestral metabolic systems. The mechanism for natural selection and evolution in autocatalytic chemical systems may be affected by natural homeostatic parameters such as ambient chemical potentials, temperature, and pressure. Competition between separate parts of an autocatalytic network with positive-plus-negative feedback resulted in the formation of primordial autotrophic, mixotrophic, and heterotrophic metabolic systems. This work examined the last common ancestor of a set of coupled metabolic cycles in a population of protocells. Physical-chemical properties of these cycles determined the main principles of natural selection for the ancestral Bacteria and Archaea taxa.

The Emergence of Bioenergetics: The Formation of a Gluconeogenesis System and Reductive Pentose Phosphate Pathway of CO2 Fixation in Ancient Hydrothermal Systems

“…In this case, the number of independent components is the smallest number of chemical components; the compositions of all possible phases of the system can be obtained by their combination. The phase rule is not limited to consideration of the extensive parameters of the system and, hence, is completely applicable to open systems with chemical potential as an independent parameter [16,30]. Determining the total number of system independent parameters (intensive and extensive), and using this number together with the Gibbs phase rule provides a way to study the thermodynamic properties of organic systems.…”

“…[40] and were designed for non-ionized forms using the method described in refs., [40,41]. The constants for substances in the C-H-O system were taken from [16]. Certainly, the hydrothermal systems are generally characterized by a more high-pressure and high-temperature conditions.…”

“…It is rationalized that these systems are the primordial metabolic autocatalytic reductive citrate (RC) cycle (reductive tricarboxylic acid, Arnon-Buchanan cycles) and 3-hydroxipropionate cycle. An important factor in the stability and subsequent evolution of these coupled cycles is the reversibility of some key chemical reactions such as succinate ↔ fumarate, malate ↔ fumarate and others [16]. The further development of this system with negative feedback involves increasing the number of independent components by maintaining additional supply of phosphorus, nitrogen, and sulfur.…”

Natural selection in coupled autocatalytic modules of carboxylic and phosphoric acids

“…In our previous works [6,7], we considered ther modynamic factors of natural selection in coupled autocatalytic cycles of CO 2 fixation (redundant mod ular structures) in the C-H-O system under various external conditions. Further development of this neg ative feedback system in a hydrothermal medium can be done by increasing the number of independent components by adding phosphorus, nitrogen, and sul fur.…”

“…3, the oxaloacetate-phos µ CO 2 µ CO 2 phoenolpyruvate paragenesis is a bifurcation point controlling the natural selection of primitive gluco neogenesis and primitive pathways of CO 2 fixation. We previously [7] considered malate as a bifurca tion point determining the development of coupled moduli of autocatalytic cycles toward stable protomet abolic systems under the control of temperature, pres sure, and the chemical potentials of H 2 , CO 2 , H 2 O, and H + in the surrounding hydrothermal medium. The diagram in Fig.…”