Heterogeneous popularity of metabolic reactions from evolution

TL;DR

This paper presents an evolutionary model explaining the heterogenous distribution of metabolic reactions across species, matching empirical data and revealing underlying mechanisms of reaction popularity.

Contribution

The study introduces a stochastic evolutionary model that reproduces the power-law distribution of reaction popularity observed in bacterial species.

Findings

Reproduces the power-law distribution of reaction popularity.

Aligns simulated network structures with empirical data.

Explains the heterogeneity in reaction presence across species.

Abstract

The composition of cellular metabolism is different across species. Empirical data reveal that bacterial species contain similar numbers of metabolic reactions but that the cross-species popularity of reactions is so heterogenous that some reactions are found in all the species while others are in just few species, characterized by a power-law distribution with the exponent one. Introducing an evolutionary model concretizing the stochastic recruitment of chemical reactions into the metabolism of different species at different times and their inheritance to descendants, we demonstrate that the exponential growth of the number of species containing a reaction and the saturated recruitment rate of brand-new reactions lead to the empirically identified power-law popularity distribution. Furthermore, the structural characteristics of metabolic networks and the species' phylogeny in our simulations agree well with empirical observations.