Mutational analysis of assembly and function of the iron-sulfur protein of the cytochrome bc1 complex in Saccharomyces cerevisiae.
The iron-sulfur protein of the cytochrome bc1 complex oxidizes ubiquinol at center P in the protonmotive Q cycle mechanism, transferring one electron to cytochrome c1 and generating a low-potential ubisemiquinone anion which reduces the low-potential cytochrome b-566 heme group. In order to catalyze this divergent transfer of two reducing equivalents from ubiquinol, the iron-sulfur protein must be structurally integrated into the cytochrome bc1 complex in a manner which facilitates electron transfer from the iron-sulfur cluster to cytochrome c1 and generates a strongly reducing ubisemiquinone anion radical which is proximal to the b-566 heme group. This radical must also be sequestered from spurious reactivities with oxygen and other high-potential oxidants. Experimental approaches are described which are aimed at understanding how the iron-sulfur protein is inserted into center P, and how the iron-sulfur cluster is inserted into the apoprotein.
Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755.
L A
LA
Graham
U
U
Brandt
J S
JS
Sargent
B L
BL
Trumpower
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry; D002384:Catalysis; D004579:Electron Transport; D014450:Electron Transport Complex III / Q000235:genetics / Q000502:physiology*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000235:genetics / Q000502:physiology*; D008928:Mitochondria / Q000201:enzymology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010084:Oxidation-Reduction; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014451:Ubiquinone / Q000031:analogs & derivatives / Q000378:metabolism
D001426:Bacterial Proteins; D005656:Fungal Proteins; D007506:Iron-Sulfur Proteins; D010940:Plant Proteins; C037989:Rieske iron-sulfur protein; D014451:Ubiquinone; D014450:Electron Transport Complex III; C003741:ubiquinol