Proton-Translocating Enzyme Mechanisms in Mitochondrial Metabolism

Proton translocation across the inner mitochondrial membrane underpins energy conversion and redox regulation in eukaryotic cells. Central to this process are membrane-embedded enzyme complexes that couple exergonic redox reactions to vectorial proton movement. The respiratory chain complexes I, III and IV establish the proton-motive force, while ATP synthase harnesses this gradient to drive ATP formation. Complementary to these are proton-translocating transhydrogenases, which exploit the proton-motive force to transfer hydride ions between NAD(H) and NADP(H), thus sustaining mitochondrial NADPH pools required for antioxidant defence, biosynthesis and metabolic flexibility. Mechanistic studies combining high-resolution structures, site-directed mutagenesis and in vivo models have revealed intricate conformational coupling between distant active sites, proton channels formed by multi-helix bundles and dynamic domain rearrangements. Dysregulation of these proton circuits is implicated in ageing, neurodegeneration, cancer and metabolic disorders, highlighting the global significance of proton-circuit integrity. Advances in bioenergetic profiling and structural biology promise novel avenues for therapeutic interventions targeting proton-translocating enzymes in mitochondrial pathologies.

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Proton-Translocating Enzyme Mechanisms in Mitochondrial Metabolism publication trend

The graph below shows the total number of articles in proton-translocating enzyme mechanisms in mitochondrial metabolism across all publications each year (not limited to Nature Index journals).

Technical terms

Proton-motive force (pmf): The electrochemical gradient of protons across the inner mitochondrial membrane that drives ATP synthesis and energises proton-translocating enzymes.

Transhydrogenase (NNT): A membrane-bound enzyme that uses the proton-motive force to catalyse hydride transfer between NADH and NADP+, linking redox balance to proton circulation.

ATP synthase: A multi-subunit complex that uses proton flow down its electrochemical gradient to synthesise ATP from ADP and inorganic phosphate.

Redox homeostasis: The maintenance of balanced oxidation and reduction reactions in cells, crucial for controlling reactive oxygen species and supporting metabolic processes.

References

1. Aging-dependent mitochondrial bioenergetic impairment in the skeletal muscle of NNT-deficient mice. Experimental Gerontology (2024).
2. The Contribution of Nicotinamide Nucleotide Transhydrogenase to Peroxide Detoxification Is Dependent on the Respiratory State and Counterbalanced by Other Sources of NADPH in Liver Mitochondria*. Journal of Biological Chemistry (2016).
3. Proton-Translocating Nicotinamide Nucleotide Transhydrogenase: A Structural Perspective. Frontiers in Physiology (2017).