The efficiency and plasticity of mitochondrial energy transduction.

TitleThe efficiency and plasticity of mitochondrial energy transduction.
Publication TypeJournal Article
Year of Publication2005
AuthorsBrand, MD
JournalBiochem Soc Trans
IssuePt 5
Date Published2005 Nov
KeywordsAdenosine Triphosphate, Animals, Energy Metabolism, Mitochondria, Models, Biological, Oxygen Consumption, Uncoupling Agents

Since it was first realized that biological energy transduction involves oxygen and ATP, opinions about the amount of ATP made per oxygen consumed have continually evolved. The coupling efficiency is crucial because it constrains mechanistic models of the electron-transport chain and ATP synthase, and underpins the physiology and ecology of how organisms prosper in a thermodynamically hostile environment. Mechanistically, we have a good model of proton pumping by complex III of the electron-transport chain and a reasonable understanding of complex IV and the ATP synthase, but remain ignorant about complex I. Energy transduction is plastic: coupling efficiency can vary. Whether this occurs physiologically by molecular slipping in the proton pumps remains controversial. However, the membrane clearly leaks protons, decreasing the energy funnelled into ATP synthesis. Up to 20% of the basal metabolic rate may be used to drive this basal leak. In addition, UCP1 (uncoupling protein 1) is used in specialized tissues to uncouple oxidative phosphorylation, causing adaptive thermogenesis. Other UCPs can also uncouple, but are tightly regulated; they may function to decrease coupling efficiency and so attenuate mitochondrial radical production. UCPs may also integrate inputs from different fuels in pancreatic beta-cells and modulate insulin secretion. They are exciting potential targets for treatment of obesity, cachexia, aging and diabetes.

Alternate JournalBiochem. Soc. Trans.
Citation Key10.1042/BST20050897
PubMed ID16246006
Grant List / / Wellcome Trust / United Kingdom