title: Gluing the respiratory chain together. Cardiolipin is required for supercomplex formation in the inner mitochondrial membrane.
abstract: Cytochrome bc(1) complex (complex III) and cytochrome c oxidase complex (complex IV) are multisubunit homodimers that are essential components of the mitochondrial respiratory chain. Complexes III and IV associate to form a supercomplex that can be displayed using blue native polyacrylamide gel electrophoresis. Both homodimeric complexes contain tightly associated cardiolipin (CL) required for function. We report here that in a crd1Delta strain of yeast (null in expression of CL synthase) approximately 90% of complexes III and IV were observed as individual homodimers; only the supercomplex was observed with CRD1 wild type cells. Introduction of a plasmid born copy of the CRD1 gene under exogenous regulation by doxycycline made possible controlled variation in the in vivo CL levels. At an intermediate level of CL, a mixture of individual homodimers (30%) and supercomplex (70%) was observed. These results strongly indicate that CL plays a central role in higher order organization of components of the respiratory chain of mitochondria.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002308:Cardiolipins / Q000378:metabolism / Q000502:physiology*; D019281:Dimerization; D004318:Doxycycline / Q000494:pharmacology; D004579:Electron Transport; D014450:Electron Transport Complex III / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005656:Fungal Proteins / Q000502:physiology; D007425:Intracellular Membranes / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D009154:Mutation; D010743:Phospholipids / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D002308:Cardiolipins; D005656:Fungal Proteins; D010743:Phospholipids; D003576:Electron Transport Complex IV; D014450:Electron Transport Complex III; D004318:Doxycycline