title: Binding of the Covalent Flavin Assembly Factor to the Flavoprotein Subunit of Complex II.
abstract: Escherichia coli harbors two highly conserved homologs of the essential mitochondrial respiratory complex II (succinate:ubiquinone oxidoreductase). Aerobically the bacterium synthesizes succinate:quinone reductase as part of its respiratory chain, whereas under microaerophilic conditions, the quinol:fumarate reductase can be utilized. All complex II enzymes harbor a covalently bound FAD co-factor that is essential for their ability to oxidize succinate. In eukaryotes and many bacteria, assembly of the covalent flavin linkage is facilitated by a small protein assembly factor, termed SdhE in E. coli. How SdhE assists with formation of the covalent flavin bond and how it binds the flavoprotein subunit of complex II remain unknown. Using photo-cross-linking, we report the interaction site between the flavoprotein of complex II and the SdhE assembly factor. These data indicate that SdhE binds to the flavoprotein between two independently folded domains and that this binding mode likely influences the interdomain orientation. In so doing, SdhE likely orients amino acid residues near the dicarboxylate and FAD binding site, which facilitates formation of the covalent flavin linkage. These studies identify how the conserved SdhE assembly factor and its homologs participate in complex II maturation.
authors.affiliation: From the Molecular Biology Division, Veterans Affairs Medical Center, San Francisco, California 94121, the Department of Biochemistry & Biophysics, University of California, San Francisco, California 94158.
authors.forename: Elena
authors.initials: E
authors.lastname: Maklashina
authors.affiliation: From the Molecular Biology Division, Veterans Affairs Medical Center, San Francisco, California 94121.
authors.forename: Sany
authors.initials: S
authors.lastname: Rajagukguk
authors.affiliation: the Graduate Program in Chemical and Physical Biology.
authors.forename: Chrystal A
authors.initials: CA
authors.lastname: Starbird
authors.affiliation: the Department of Biochemistry and Mass Spectrometry Research Center.
authors.forename: W Hayes
authors.initials: WH
authors.lastname: McDonald
authors.affiliation: the Department of Biological Chemistry, Weizmann Institute of Science, 76100 Rehovot, Israel.
authors.forename: Anna
authors.initials: A
authors.lastname: Koganitsky
authors.affiliation: the Department of Biological Chemistry, Weizmann Institute of Science, 76100 Rehovot, Israel.
authors.forename: Michael
authors.initials: M
authors.lastname: Eisenbach
authors.affiliation: the Department of Biochemistry and Mass Spectrometry Research Center, the Department of Pharmacology, the Center for Structural Biology, and the Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, and.
authors.forename: Tina M
authors.initials: TM
authors.lastname: Iverson
authors.affiliation: From the Molecular Biology Division, Veterans Affairs Medical Center, San Francisco, California 94121, the Department of Biochemistry & Biophysics, University of California, San Francisco, California 94158, Gary.Cecchini@ucsf.edu.
authors.forename: Gary
authors.initials: G
authors.lastname: Cecchini
mesh_terms: D042963:Electron Transport Complex II / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005182:Flavin-Adenine Dinucleotide / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D005182:Flavin-Adenine Dinucleotide; D042963:Electron Transport Complex II
keywords: chaperone; complex II; flavin adenine dinucleotide (FAD); fumarate reductase; mitochondrial respiratory chain complex; protein assembly; protein self-assembly; protein-protein interaction; succinate dehydrogenase