title: The presence of rotenone-sensitive NADH dehydrogenase in the long slender bloodstream and the procyclic forms of Trypanosoma brucei brucei.
abstract: The mitochondrial electron-transport chain present in the procyclic and long slender bloodstream forms of Trypanosoma brucei brucei was investigated by means of several experimental approaches. The oxidation of proline, glycerol and glucose in procyclic cells was inhibited 80-90% by antimycin A or cyanide, 15-19% by salicylhydroxamic acid, and 30-35% by rotenone. Cytochrom-c-reductase activity, with proline or glycerol 3-phosphate as substrate, in a mitochondrial fraction isolated from these cells was inhibited by antimycin and rotenone, but not by malonate, while cytochrome-c-reductase activity with succinate as substrate was inhibited by antimycin A and malonate, but not by rotenone. In addition, the reduction of dichloroindophenol by NADH was inhibited by rotenone but not by malonate, which suggests that rotenone-sensitive NADH dehydrogenase (complex I) is present in these mitochondria. The presence of three subunits of NADH dehydrogenase was observed in immunoblots of mitochondrial proteins with specific antibodies raised against peptides corresponding to predicted antigenic regions of these proteins, which provides further evidence for the presence of NADH dehydrogenase. In long slender bloodstream forms, the oxidation of glucose or glycerol was inhibited 100% by salicyhydroxamic acid, unaffected by cyanide or antimycin A, and inhibited 40% or 75%, respectively, by rotenone, which suggests that NADH dehydrogenase is present in these cells. In a mitochondrial fraction isolated from the bloodstream forms, oxygen uptake with glycerol 3-phosphate as substrate was inhibited 65% by rotenone. Low levels of rotenone-sensitive NADH-dependent reduction of dichloroindophenol and the presence of subunits 7 and 8 of NADH dehydrogenase provided additional evidence for the presence of NADH dehydrogenase in bloodstream forms of T. brucei.
authors.affiliation: Department of Biochemistry, West Virginia University, Morgantown 26506, USA.
authors.forename: D S
authors.initials: DS
authors.lastname: Beattie
authors.forename: M M
authors.initials: MM
authors.lastname: Howton
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D004579:Electron Transport; D042967:Electron Transport Complex I; D005993:Glycerolphosphate Dehydrogenase / Q000032:analysis; D015151:Immunoblotting; D008928:Mitochondria / Q000201:enzymology*; D009245:NADH Dehydrogenase / Q000187:drug effects; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects; D011487:Protein Conformation; D012402:Rotenone / Q000494:pharmacology*; D014346:Trypanosoma brucei brucei / Q000166:cytology / Q000201:enzymology*; D014475:Uncoupling Agents / Q000494:pharmacology*
chemical_list: D014475:Uncoupling Agents; D012402:Rotenone; D005993:Glycerolphosphate Dehydrogenase; D009247:NADH, NADPH Oxidoreductases; D009245:NADH Dehydrogenase; D042967:Electron Transport Complex I