Mitochondria form discrete organelles or connected networks; yet it remains unclear how this structure affects mitochondrial function. On Giovanni Benard and co-authors report that mitochondrial-network organisation and bioenergetics are intricately linked. To investigate the importance of mitochondrial fission on energy production the authors suppressed dynamin-related protein-1 (Drp1), a key mediator of this process, using RNAi. This revealed a dramatic reduction in energy production as a result of alterations in mitochondrial membrane fluidity. They assessed the impact that inhibition of oxidative phosphorylation has on mitochondrial-network organisation and demonstrated that inhibition of respiratory chain complex I using rotenone causes gross structural perturbations to the mitochondrial reticulum. Furthermore, using fibroblasts from patients with mitochondrial disease and human cells treated with modulators of oxidative phosphorylation, the authors were able to conclude that the rate of ATP production probably dictates mitochondrial morphology. They propose that the flux-force relationship of mitochondrial oxidative phosphorylation is the major factor determining mitochondrial shape and network organisation.
