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An electronic bus bar lies in the core of cytochrome bc1.

ABSTRACT: The ubiquinol-cytochrome c oxidoreductases, central to cellular respiration and photosynthesis, are homodimers. High symmetry has frustrated resolution of whether cross-dimer interactions are functionally important. This has resulted in a proliferation of contradictory models. Here, we duplicated and fused cytochrome b subunits, and then broke symmetry by introducing independent mutations into each monomer. Electrons moved freely within and between monomers, crossing an electron-transfer bridge between two hemes in the core of the dimer. This revealed an H-shaped electron-transfer system that distributes electrons between four quinone oxidation-reduction terminals at the corners of the dimer within the millisecond time scale of enzymatic turnover. Free and unregulated distribution of electrons acts like a molecular-scale bus bar, a design often exploited in electronics.

SUBMITTER: Swierczek M

PROVIDER: S-EPMC4073802 | biostudies-literature | 2010 Jul

REPOSITORIES: biostudies-literature

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An electronic bus bar lies in the core of cytochrome bc1.

Swierczek Monika M Cieluch Ewelina E Sarewicz Marcin M Borek Arkadiusz A Moser Christopher C CC Dutton P Leslie PL Osyczka Artur A

Science (New York, N.Y.) 20100701 5990

The ubiquinol-cytochrome c oxidoreductases, central to cellular respiration and photosynthesis, are homodimers. High symmetry has frustrated resolution of whether cross-dimer interactions are functionally important. This has resulted in a proliferation of contradictory models. Here, we duplicated and fused cytochrome b subunits, and then broke symmetry by introducing independent mutations into each monomer. Electrons moved freely within and between monomers, crossing an electron-transfer bridge ...[more]

PMID: 20651150

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