Mutational analysis of assembly and function of the iron-sulfur protein of the cytochromebc 1 complex inSaccharomyces cerevisiae |
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Authors: | Laurie A. Graham Ulrich Brandt John S. Sargent Bernard L. Trumpower |
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Affiliation: | (1) Department of Biochemistry, Dartmouth Medical School, 03755 Hanover, New Hampshire |
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Abstract: | The iron-sulfur protein of the cytochromebc1 complex oxidizes ubiquinol at center P in the protonmotive Q cycle mechanism, transferring one electron to cytochromec1 and generating a low-potential ubisemiquinone anion which reduces the low-potential cytochromeb-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 cytochromebc1 complex in a manner which facilitates electron transfer from the iron-sulfur cluster to cytochromec1 and generates a strongly reducing ubisemiquinone anion radical which is proximal to theb-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. |
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Keywords: | Rieske iron-sulfur protein, RIP1 Saccharomyces cerevisiae mitochondria bc1 complex QCR9 iron-sulfur cluster, mitochondrial targeting |
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