title: Structure of fumarate reductase from Wolinella succinogenes at 2.2 A resolution.
abstract: Fumarate reductase couples the reduction of fumarate to succinate to the oxidation of quinol to quinone, in a reaction opposite to that catalysed by the related complex II of the respiratory chain (succinate dehydrogenase). Here we describe the crystal structure at 2.2 A resolution of the three protein subunits containing fumarate reductase from the anaerobic bacterium Wolinella succinogenes. Subunit A contains the site of fumarate reduction and a covalently bound flavin adenine dinucleotide prosthetic group. Subunit B contains three iron-sulphur centres. The menaquinol-oxidizing subunit C consists of five membrane-spanning, primarily helical segments and binds two haem b molecules. On the basis of the structure, we propose a pathway of electron transfer from the dihaem cytochrome b to the site of fumarate reduction and a mechanism of fumarate reduction. The relative orientations of the soluble and membrane-embedded subunits of succinate:quinone oxidoreductases appear to be unique.
authors.affiliation: Max-Planck-Institut für Biophysik, Frankfurt am Main, Germany. lancaster@mpibp-frankfurt.mpg.de
authors.forename: C R
authors.initials: CR
authors.lastname: Lancaster
authors.forename: A
authors.initials: A
authors.lastname: Kröger
authors.forename: M
authors.initials: M
authors.lastname: Auer
authors.forename: H
authors.initials: H
authors.lastname: Michel
mesh_terms: D002462:Cell Membrane / Q000201:enzymology; D018360:Crystallography, X-Ray; D003998:Dicarboxylic Acids / Q000378:metabolism; D004579:Electron Transport; D004926:Escherichia coli / Q000201:enzymology; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism; D006418:Heme / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000378:metabolism; D008670:Metals / Q000378:metabolism; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011485:Protein Binding; D011487:Protein Conformation; D011809:Quinones / Q000378:metabolism; D012995:Solubility; D013385:Succinate Dehydrogenase / Q000737:chemistry*; D016968:Wolinella / Q000201:enzymology*
chemical_list: D003998:Dicarboxylic Acids; D007506:Iron-Sulfur Proteins; D008670:Metals; D011809:Quinones; D005182:Flavin-Adenine Dinucleotide; D006418:Heme; D013385:Succinate Dehydrogenase