title: Structure of the Escherichia coli fumarate reductase respiratory complex.
abstract: The integral membrane protein fumarate reductase catalyzes the final step of anaerobic respiration when fumarate is the terminal electron acceptor. The homologous enzyme succinate dehydrogenase also plays a prominent role in cellular energetics as a member of the Krebs cycle and as complex II of the aerobic respiratory chain. Fumarate reductase consists of four subunits that contain a covalently linked flavin adenine dinucleotide, three different iron-sulfur clusters, and at least two quinones. The crystal structure of intact fumarate reductase has been solved at 3.3 angstrom resolution and demonstrates that the cofactors are arranged in a nearly linear manner from the membrane-bound quinone to the active site flavin. Although fumarate reductase is not associated with any proton-pumping function, the two quinones are positioned on opposite sides of the membrane in an arrangement similar to that of the Q-cycle organization observed for cytochrome bc1.
authors.affiliation: Graduate Option in Biochemistry, 147-75CH, California Institute of Technology, Pasadena, CA 91125, USA.
authors.forename: T M
authors.initials: TM
authors.lastname: Iverson
authors.forename: C
authors.initials: C
authors.lastname: Luna-Chavez
authors.forename: G
authors.initials: G
authors.lastname: Cecchini
authors.forename: D C
authors.initials: DC
authors.lastname: Rees
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D001665:Binding Sites; D002462:Cell Membrane / Q000201:enzymology; D003460:Crystallization; D018360:Crystallography, X-Ray; D004579:Electron Transport; D004734:Energy Metabolism; D004926:Escherichia coli / Q000201:enzymology*; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism; D005650:Fumarates / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D011487:Protein Conformation; D017510:Protein Folding; D011809:Quinones / Q000737:chemistry / Q000378:metabolism; D013385:Succinate Dehydrogenase / Q000737:chemistry* / Q000378:metabolism
chemical_list: D005650:Fumarates; D007506:Iron-Sulfur Proteins; D011809:Quinones; D005182:Flavin-Adenine Dinucleotide; C032005:fumaric acid; D013385:Succinate Dehydrogenase