  Metabolic models condense biochemical knowledge about organisms in a
structured and standardised way. As large-scale network reconstructions are
readily available for many organisms of interest, genome-scale models are being
widely used among modellers and engineers. However, these large models can be
difficult to analyse and visualise, and occasionally generate hard-to-interpret
or even biologically unrealistic predictions. Out of the thousands of enzymatic
reactions in a typical bacterial metabolism, only a few hundred comprise the
metabolic pathways essential to produce energy carriers and biosynthetic
precursors. These pathways carry relatively high flux, are central to
maintaining and reproducing the cell, and provide precursors and energy to
engineered metabolic pathways. Here, focusing on these central metabolic
subsystems, we present a manually-curated medium-scale model of energy and
biosynthesis metabolism for the well-studied prokaryote Escherichia coli K-12
MG1655. The model is a sub-network of the most recent genome-scale
reconstruction, iML1515, and comes with an updated layer of database
annotations, as well as a range of metabolic maps for visualisation. We
enriched the stoichiometric network with extensive biological information and
quantitative data, enhancing the scope and applicability of the model. In
addition, here we assess the properties of this model in relation to its
genome-scale parent and demonstrate the use of the network and supporting data
in various scenarios, including enzyme-constrained flux balance analysis,
elementary flux mode analysis, and thermodynamic analysis. Overall, we believe
this model holds the potential to become a reference medium-scale metabolic
model for E. coli.
