Predicting metabolism during growth by osmotic cell expansion (bioRxiv)

Growth is driven by cell expansion, which is driven by both synthesis of metabolites and osmotically-driven expansion. This latter contribution is typically overlooked in metabolic flux analysis. To remedy this, Shameer et al. have developed a model, GrOE-FBA (Growth by Osmotic Expansion- Flux Balance Analysis). By combining previously described osmotic constraints with biomass constraints, they were able to perform flux-balance analysis (FBA) while accounting for cell volume. They used their model to analyze the metabolic fluxes in dividing and expanding cells. Their predicted values matched closely to experimentally measured values. Interestingly, their data show that the metabolic demands of growth by cell expansion are closely matched to those of growth by cell division, probably due to the metabolic costs of synthesizing and importing osmolytes. Their model provides insights into fruit development, including suggesting an explanation for the requirement for a transitory carbohydrate store in expanding fruits. (Summary by Mary Williams) bioRxiv 10.1101/731232