Architecture of active mammalian respiratory chain supercomplexes.
In the inner mitochondrial membrane, the respiratory chain complexes generate an electrochemical proton gradient, which is utilized to synthesize most of the cellular ATP. According to an increasing number of biochemical studies, these complexes are assembled into supercomplexes. However, little is known about the architecture of the proposed multicomplex assemblies. Here, we report the electron microscopic characterization of the two respiratory chain supercomplexes I1III2 and I1III2IV1 in bovine heart mitochondria, which are also two major supercomplexes in human mitochondria. After purification and demonstration of enzymatic activity, their structures in projection were determined by single particle image analysis. A difference map between the supercomplexes I1III2 and I1III2IV1 closely fits the x-ray structure of monocomplex IV and shows its location in the assembly. By comparing different views of supercomplex I1III2IV1, the location and mutual arrangement of complex I and the complex III dimer are discussed. Detailed knowledge of the architecture of the active supercomplexes is a prerequisite for a deeper understanding of energy conversion by mitochondria in mammals.
Department of Chemistry, Physical Biochemistry, Darmstadt University of Technology, Petersenstrasse 22, D-64287 Darmstadt, Germany.
Eva
E
Schäfer
Holger
H
Seelert
Nicole H
NH
Reifschneider
Frank
F
Krause
Norbert A
NA
Dencher
Janet
J
Vonck
D000818:Animals; D002417:Cattle; D004579:Electron Transport; D045222:Electron Transport Chain Complex Proteins / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure*; D042967:Electron Transport Complex I / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D014450:Electron Transport Complex III / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D003576:Electron Transport Complex IV / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D066298:In Vitro Techniques; D008854:Microscopy, Electron; D008929:Mitochondria, Heart / Q000378:metabolism; D008958:Models, Molecular; D046912:Multiprotein Complexes
D045222:Electron Transport Chain Complex Proteins; D046912:Multiprotein Complexes; D003576:Electron Transport Complex IV; D042967:Electron Transport Complex I; D014450:Electron Transport Complex III