Phosphoglycerate mutases function as reverse regulated isoenzymes in Synechococcus elongatus PCC 7942.

Jiri Jablonsky, Martin Hagemann, Doreen Schwarz, Olaf Wolkenhauer

PloS one 2013

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Phosphoglycerate-mutase (PGM) is an ubiquitous glycolytic enzyme, which in eukaryotic cells can be found in different compartments. In prokaryotic cells, several PGMs are annotated/localized in one compartment. The identification and functional characterization of PGMs in prokaryotes is therefore important for better understanding of metabolic regulation. Here we introduce a method, based on a multi-level kinetic model of the primary carbon metabolism in cyanobacterium Synechococcus elongatus PCC 7942, that allows the identification of a specific function for a particular PGM. The strategy employs multiple parameter estimation runs in high CO2, combined with simulations testing a broad range of kinetic parameters against the changes in transcript levels of annotated PGMs. Simulations are evaluated for a match in metabolic level in low CO2, to reveal trends that can be linked to the function of a particular PGM. A one-isoenzyme scenario shows that PGM2 is a major regulator of glycolysis, while PGM1 and PGM4 make the system robust against environmental changes. Strikingly, combining two PGMs with reverse transcriptional regulation allows both features. A conclusion arising from our analysis is that a two-enzyme PGM system is required to regulate the flux between glycolysis and the Calvin-Benson cycle, while an additional PGM increases the robustness of the system.

Citation

Jiri Jablonsky, Martin Hagemann, Doreen Schwarz, Olaf Wolkenhauer. Phosphoglycerate mutases function as reverse regulated isoenzymes in Synechococcus elongatus PCC 7942. PloS one. 2013;8(3):e58281