Structural Basis of Multifunctional Bovine Mitochondrial Cytochrome bc
1 Complex |
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Authors: | Chang-An Yu Hua Tian Li Zhang Kai-Ping Deng Sudha K Shenoy Linda Yu Di Xia Hoeon Kim Johann Deisenhofer |
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Institution: | (1) Present address: Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, 74078-3035;(2) The Howard Hughes Medical Institute and Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, 75235;(3) Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, 20892 |
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Abstract: | The mitochondrial cytochrome bc
1 complex is a multifunctional membrane protein complex. Itcatalyzes electron transfer, proton translocation, peptide processing, and superoxide generation.Crystal structure data at 2.9 Å resolution not only establishes the location of the redox centersand inhibitor binding sites, but also suggests a movement of the head domain of the iron–sulfurprotein (ISP) during bc
1 catalysis and inhibition of peptide-processing activity during complexmaturation. The functional importance of the movement of extramembrane (head) domain ofISP in the bc
1 complex is confirmed by analysis of the Rhodobacter sphaeroides bc
1 complexmutants with increased rigidity in the ISP neck and by the determination of rate constants foracid/base-induced intramolecular electron transfer between 2Fe–2S] and heme c
1 in nativeand inhibitor-loaded beef complexes. The peptide-processing activity is activated in bovineheart mitochondrial bc
1 complex by nonionic detergent at concentrations that inactivate electrontransfer activity. This peptide-processing activity is shown to be associated with subunits Iand II by cloning, overexpression and in vitro reconstitution. The superoxide-generation siteof the cytochrome bc
1 complex is located at reduced b
L and Q –. The reaction is membranepotential-, and cytochrome c-dependent. |
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Keywords: | cytochrome bc
1 complex electron transfer reaction: mitochondrial-processing peptidase superoxide-generation activity electron transfer inhibitors |
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