title: Biochemical and evolutionary aspects of anaerobically functioning mitochondria.
abstract: Mitochondria are usually considered to be the powerhouses of the cell and to be responsible for the aerobic production of ATP. However, many eukaryotic organisms are known to possess anaerobically functioning mitochondria, which differ significantly from classical aerobically functioning mitochondria. Recently, functional and phylogenetic studies on some enzymes involved clearly indicated an unexpected evolutionary relationship between these anaerobically functioning mitochondria and the classical aerobic type. Mitochondria evolved by an endosymbiotic event between an anaerobically functioning archaebacterial host and an aerobic alpha-proteobacterium. However, true anaerobically functioning mitochondria, such as found in parasitic helminths and some lower marine organisms, most likely did not originate directly from the pluripotent ancestral mitochondrion, but arose later in evolution from the aerobic type of mitochondria after these were already adapted to an aerobic way of life by losing their anaerobic capacities. This review will focus on some biochemical and evolutionary aspects of these fermentative mitochondria, with special attention to fumarate reductase, the synthesis of the rhodoquinone involved, and the enzymes involved in acetate production (acetate : succinate CoA-transferase and succinyl CoA-synthetase).
authors.affiliation: Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, PO Box 80176, 3508 TD Utrecht, The Netherlands.
authors.forename: Jaap J
authors.initials: JJ
authors.lastname: van Hellemond
authors.forename: Anita
authors.initials: A
authors.lastname: van der Klei
authors.forename: Susanne W H
authors.initials: SW
authors.lastname: van Weelden
authors.forename: Aloysius G M
authors.initials: AG
authors.lastname: Tielens
mesh_terms: D000085:Acetates / Q000378:metabolism; D000332:Aerobiosis; D000693:Anaerobiosis; D000818:Animals; D005075:Biological Evolution; D004579:Electron Transport; D005285:Fermentation; D008928:Mitochondria / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism*; D010802:Phylogeny; D013385:Succinate Dehydrogenase / Q000378:metabolism; D014451:Ubiquinone / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D000085:Acetates; D014451:Ubiquinone; D013385:Succinate Dehydrogenase; C003304:rhodoquinone