title: Cardiolipin-dependent reconstitution of respiratory supercomplexes from purified Saccharomyces cerevisiae complexes III and IV.
abstract: Here, we report for the first time in vitro reconstitution of the respiratory supercomplexes from individual complexes III and IV. Complexes III and IV were purified from Saccharomyces cerevisiae mitochondria. Complex III contained eight molecules of cardiolipin, and complex IV contained two molecules of cardiolipin, as determined by electrospray ionization-mass spectrometry. Complex IV also contained Rcf1p. No supercomplexes were formed upon mixing of the purified complexes, and low amounts of the supercomplex trimer III(2)IV(1) were formed after reconstitution into proteoliposomes containing only phosphatidylcholine and phosphatidylethanolamine. Further addition of cardiolipin to the proteoliposome reconstitution mixture resulted in distinct formation of both the III(2)IV(1) supercomplex trimer and III(2)IV(2) supercomplex tetramer. No other anionic phospholipid was as effective as cardiolipin in supporting tetramer formation. Phospholipase treatment of complex IV prevented trimer formation in the absence of cardiolipin. Both trimer and tetramer formations were restored by cardiolipin. Analysis of the reconstituted tetramer by single particle electron microscopy confirmed native organization of individual complexes within the supercomplex. In conclusion, although some trimer formation occurred dependent only on tightly bound cardiolipin, tetramer formation required additional cardiolipin. This is consistent with the high cardiolipin content in the native tetramer. The dependence on cardiolipin for supercomplex formation suggests that changes in cardiolipin levels resulting from changes in physiological conditions may control the equilibrium between individual respiratory complexes and supercomplexes in vivo.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas at Houston Medical School, Houston, Texas 77030, USA.
authors.forename: Soledad
authors.initials: S
authors.lastname: Bazán
authors.forename: Eugenia
authors.initials: E
authors.lastname: Mileykovskaya
authors.forename: Venkata K P S
authors.initials: VK
authors.lastname: Mallampalli
authors.forename: Philip
authors.initials: P
authors.lastname: Heacock
authors.forename: Genevieve C
authors.initials: GC
authors.lastname: Sparagna
authors.forename: William
authors.initials: W
authors.lastname: Dowhan
mesh_terms: D002308:Cardiolipins / Q000737:chemistry*; D003579:Cytochrome Reductases / Q000737:chemistry; D014450:Electron Transport Complex III / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000737:chemistry / Q000378:metabolism*; D008055:Lipids / Q000737:chemistry; D008854:Microscopy, Electron / Q000379:methods; D008928:Mitochondria / Q000378:metabolism; D010740:Phospholipases / Q000737:chemistry; D011485:Protein Binding; D011510:Proteolipids / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D014451:Ubiquinone / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D002308:Cardiolipins; D008055:Lipids; D011510:Proteolipids; C020485:proteoliposomes; D014451:Ubiquinone; D003579:Cytochrome Reductases; D003576:Electron Transport Complex IV; D010740:Phospholipases; D014450:Electron Transport Complex III; C003741:ubiquinol