Heterogeneous distribution and organization of cytoskeletal proteins drive differential modulation of metabolic fluxes

On the basis of experimental data obtained in vitro, we propose that differential segregation of actin and tubulin in the cytoplasm may be a regulatory mechanism of metabolic fluxes. The results presented point out that the same enzymes may be differentially modulated at different locations in the cytoplasm, depending on the cytoskeletal protein present at that location, its concentration, polymeric status, or geometric arrangement. Essentially, actin or microtubular protein would exert their effect on enzymatic catalysis through displacement of the equilibrium of enzyme oligomers either to active or less active species. The latter was corroborated by mathematical modeling of the dynamic coupling between microtubular protein assembly-disassembly and pyruvate kinase activity. From these results, a precise biochemical meaning can be given to the putative linkage existing between the mechanisms by which cells rearrange their cytoplasmic architecture and the dynamics of biochemical reactions taking place concomitantly.