Analysis of central carbon and energy metabolisms of growing Arabidopsis thaliana in relation to sucrose translocation

we describe a multi-compartmental model consisting of a mesophyll cell with plastid and mitochondrion, a phloem cell, as well as a root cell with mitochondrion. In this model, the phloem was considered as a non-growing transport compartment, the mesophyll compartment was considered as both autotrophic (growing on CO2 under light) and heterotrophic (growing on starch in darkness), and the root was always considered as heterotrophic tissue completely dependent on sucrose supply from the mesophyll compartment. In total, the model includes 380 balanced compounds interconnected by 372 transformers. The structured metabolic model accounts for central carbon metabolism, photosynthesis, photorespiration, carbohydrate metabolism, energy and redox metabolisms, proton metabolism, biomass growth, nutrients uptake, proton gradient generation and sucrose translocation between tissues. Biochemical processes in the model were associated with gene-products (742 ORFs) which were validated using mass-spectrometry based proteomic data. Flux Balance Analysis (FBA) of the model resulted in balanced carbon, proton, energy and redox states under both light and dark conditions. Based on the FBA, the model predictes that in light conditions the plastid produced enough ATP to serve the Calvin-Benson cycle and starch formation, and the excess of photosynthetic potential (in form of reducing equivalents) was exported to the mitochondria via malate/oxaloacetate shuttle for ATP synthesis. The main H+-fluxes were reconstructed and sucrose translocation matched with them.

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Created: 21st Dec 2015 at 13:15

Last updated: 18th Apr 2016 at 14:05

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