The evolutionary dynamics of metabolic protocells

Ximo Pechuan, Raymond Puzio, Aviv Bergman

Research output: Contribution to journalArticle

Abstract

Protocell multilevel selection models have been proposed to study the evolutionary dynamics of vesicles encapsulating a set of replicating, competing and mutating sequences. The frequency of the different sequence types determines protocell survival through a fitness function. One of the defining features of these models is the genetic load generated when the protocell divides and its sequences are assorted between the offspring vesicles. However, these stochastic assortment effects disappear when the redundancy of each sequence type is sufficiently high. The fitness dependence of the vesicle with its sequence content is usually defined without considering a realistic account on how the lower level dynamics would specify the protocell fitness. Here, we present a protocell model with a fitness function determined by the output flux of a simple metabolic network with the aim of understanding how the evolution of both kinetic and topological features of metabolism would have been constrained by the particularities of the protocell evolutionary dynamics. In our model, the sequences inside the vesicle are both the carriers of information and Michaelis-Menten catalysts exhibiting saturation. We found that the saturation of the catalysts controlling the metabolic fluxes, achievable by modifying the kinetic or stoichiometric parameters, provides a mechanism to ameliorate the assortment load by increasing the redundancy of the catalytic sequences required to achieve the maximum flux. Regarding the network architecture, we conclude that combinations of parallel network motifs and bimolecular catalysts are a robust way to increase the complexity of the metabolism enclosed by the protocell.

Original languageEnglish (US)
Article numbere1006265
JournalPLoS Computational Biology
Volume14
Issue number7
DOIs
StatePublished - Jul 1 2018

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Artificial Cells
Evolutionary Dynamics
vesicle
fitness
catalysts
Vesicles
catalyst
Fluxes
Metabolism
Catalysts
Redundancy
Catalyst
metabolism
saturation
kinetics
Enzyme kinetics
Fitness Function
Fitness
Network architecture
Saturation

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Modeling and Simulation
  • Ecology
  • Molecular Biology
  • Genetics
  • Cellular and Molecular Neuroscience
  • Computational Theory and Mathematics

Cite this

The evolutionary dynamics of metabolic protocells. / Pechuan, Ximo; Puzio, Raymond; Bergman, Aviv.

In: PLoS Computational Biology, Vol. 14, No. 7, e1006265, 01.07.2018.

Research output: Contribution to journalArticle

Pechuan, Ximo ; Puzio, Raymond ; Bergman, Aviv. / The evolutionary dynamics of metabolic protocells. In: PLoS Computational Biology. 2018 ; Vol. 14, No. 7.
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