The contribution of uncoupling protein and ATP synthase to state 3 respiration in Acanthamoeba castellanii mitochondria.
Mitochondria of the amoeba Acanthamoeba castellanii possess a free fatty acid-activated uncoupling protein (AcUCP) that mediates proton re-uptake driven by the mitochondrial proton electrochemical gradient. We show that AcUCP activity diverts energy from ATP synthesis during state 3 mitochondrial respiration in a fatty acid-dependent way. The efficiency of AcUCP in mitochondrial uncoupling increases when the state 3 respiratory rate decreases as the AcUCP contribution is constant at a given linoleic acid concentration while the ATP synthase contribution decreases with respiratory rate. Respiration sustained by this energy-dissipating process remains constant at a given linoleic acid concentration until more than 60% inhibition of state 3 respiration by n-butyl malonate is achieved. The present study supports the validity of the ADP/O method to determine the actual contributions of AcUCP (activated with various linoleic acid concentrations) and ATP synthase in state 3 respiration of A.castellanii mitochondria fully depleted of free fatty acid-activated and describes how the two contributions vary when the rate of succinate dehydrogenase is decreased by succinate uptake limitation.
Jarmuszkiewicz
Wiesława
W
Laboratory of Bioenergetics, Adam Mickiewicz University, Poznań, Poland. wiesiaj@main.amu.edu.pl
Czarna
Małgorzata
M
Sluse-Goffart
Claudine
C
Sluse
Francis E
FE
D025181:ATP Synthetase Complexes / Q000378:metabolism*; D048248:Acanthamoeba castellanii / Q000502:physiology*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism / Q000502:physiology*; D004563:Electrochemistry; D007473:Ion Channels; D019787:Linoleic Acid / Q000737:chemistry / Q000378:metabolism; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000378:metabolism / Q000502:physiology*; D024101:Mitochondrial Proteins; D008956:Models, Chemical; D010101:Oxygen Consumption; D010766:Phosphorylation; D011485:Protein Binding; D011522:Protons; D013997:Time Factors; D000071256:Uncoupling Protein 1
D002352:Carrier Proteins; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D011522:Protons; D000071256:Uncoupling Protein 1; D000255:Adenosine Triphosphate; D019787:Linoleic Acid; D025181:ATP Synthetase Complexes