title: Arrangement of the respiratory chain complexes in Saccharomyces cerevisiae supercomplex III2IV2 revealed by single particle cryo-electron microscopy.
abstract: Here we present for the first time a three-dimensional cryo-EM map of the Saccharomyces cerevisiae respiratory supercomplex composed of dimeric complex III flanked on each side by one monomeric complex IV. A precise fit of the existing atomic x-ray structures of complex III from yeast and complex IV from bovine heart into the cryo-EM map resulted in a pseudo-atomic model of the three-dimensional structure for the supercomplex. The distance between cytochrome c binding sites of complexes III and IV is about 6 nm, which supports proposed channeling of cytochrome c between the individual complexes. The opposing surfaces of complexes III and IV differ considerably from those reported for the bovine heart supercomplex as determined by cryo-EM. A closer association between the individual complex domains at the aqueous membrane interface and larger spaces between the membrane-embedded domains where lipid molecules may reside are also demonstrated. The supercomplex contains about 50 molecules of cardiolipin (CL) with a fatty acid composition identical to that of the inner membrane CL pool, consistent with CL-dependent stabilization of the supercomplex.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas-Houston Medical School, Houston, Texas 77030, USA. Eugenia.Mileykovskaya@uth.tmc.edu
authors.forename: Eugenia
authors.initials: E
authors.lastname: Mileykovskaya
authors.forename: Pawel A
authors.initials: PA
authors.lastname: Penczek
authors.forename: Jia
authors.initials: J
authors.lastname: Fang
authors.forename: Venkata K P S
authors.initials: VK
authors.lastname: Mallampalli
authors.forename: Genevieve C
authors.initials: GC
authors.lastname: Sparagna
authors.forename: William
authors.initials: W
authors.lastname: Dowhan
mesh_terms: D020285:Cryoelectron Microscopy / Q000379:methods*; D018360:Crystallography, X-Ray; D004579:Electron Transport / Q000502:physiology; D014450:Electron Transport Complex III / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D008055:Lipids / Q000737:chemistry; D008928:Mitochondria / Q000201:enzymology* / Q000648:ultrastructure; D008956:Models, Chemical; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D013045:Species Specificity; D013329:Structure-Activity Relationship
chemical_list: D008055:Lipids; D029701:Saccharomyces cerevisiae Proteins; D003576:Electron Transport Complex IV; D014450:Electron Transport Complex III