Uncoupling proteins in mitochondria of plants and some microorganisms.
Uncoupling proteins, members of the mitochondrial carrier family, are present in mitochondrial inner membrane and mediate free fatty acid-activated, purine-nucleotide-inhibited H+ re-uptake. Since 1995, it has been shown that the uncoupling protein is present in many higher plants and some microorganisms like non-photosynthetic amoeboid protozoon, Acanthamoeba castellanii and non-fermentative yeast Candida parapsilosis. In mitochondria of these organisms, uncoupling protein activity is revealed not only by stimulation of state 4 respiration by free fatty acids accompanied by decrease in membrane potential (these effects being partially released by ATP and GTP) but mainly by lowering ADP/O ratio during state 3 respiration. Plant and microorganism uncoupling proteins are able to divert very efficiently energy from oxidative phosphorylation, competing for deltamicroH+ with ATP synthase. Functional connection and physiological role of uncoupling protein and alternative oxidase, two main energy-dissipating systems in plant-type mitochondria, are discussed.
Jarmuszkiewicz
W
W
Department of Bioenergetics, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznani, Poland. wiesiaj@main.amu.edu.pl
D000048:Acanthamoeba / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D002175:Candida / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000502:physiology*; D003486:Cyanides / Q000737:chemistry; D006160:Guanosine Triphosphate / Q000378:metabolism; D007473:Ion Channels; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000737:chemistry* / Q000502:physiology*; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins; D008954:Models, Biological; D010944:Plants / Q000737:chemistry; D000071256:Uncoupling Protein 1
D002352:Carrier Proteins; D003486:Cyanides; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D000071256:Uncoupling Protein 1; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate