title: A structural model for the membrane-integral domain of succinate: quinone oxidoreductases.
abstract: Many succinate:quinone oxidoreductases in bacteria and mitochondria, i.e. succinate:quinone reductases and fumarate reductases, contain in the membrane anchor a cytochrome b whose structure and function is poorly understood. Based on biochemical data and polypeptide sequence information, we show that the anchors in different organisms are related despite an apparent diversity in polypeptide and heme composition. A general structural model for the membrane-integral domain of the anchors is proposed. It is an antiparallel four-helix bundle with a novel arrangement of hexa-coordinated protoheme IX. The structure can be applied to a larger group of membrane-integral cytochromes of b-type and has evolutionary and functional implications.
authors.affiliation: Department of Microbiology, Lund University, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Hägerhäll
authors.forename: L
authors.initials: L
authors.lastname: Hederstedt
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism; D003574:Cytochrome c Group; D042963:Electron Transport Complex II; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry* / Q000378:metabolism; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism; D013385:Succinate Dehydrogenase / Q000737:chemistry* / Q000378:metabolism
chemical_list: D003574:Cytochrome c Group; D009097:Multienzyme Complexes; D010088:Oxidoreductases; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase