Subcellular Systems Follow Onsager Reciprocity

Abstract The complexity of prokaryotic and, exceedingly, of eukaryotic cells, challenges the implemen-tation of methodologies to quantify intracellular dynamics. Although stochastic thermodynam-ics can be used to effectively quantify the energetics of single proteins or complexes, there is no statistical approach to determine the macrostate of a whole cell from its subcellular mi-crostates. The objective of this study is to test if Onsager reciprocity, a coupling between ther-modynamic flows, can be established between time-dependent intracellular processes from their measurements in previous studies. A prototypical thermodynamic profile of the cell is for-mulated as a model system to enable representation of its sub systems as force-driven ther-modynamic flows. Onsager reciprocity is validated on the bacterial flagellum and ATP syn-thase. It is then tested on the putative coupling between the contractile ring and treadmilling of the cytoskeleton in bacterial binary fission and eukaryotic cytokinesis, with opposite out-comes. All thermodynamic flows and forces are formulated to comply with their canonical defi-nitions.