Structure and reaction mechanisms of multifunctional mitochondrial cytochrome bc1 complex

Chang An Yu, Li Zhang, Kai Ping Deng, Hua Tian, Di Xia, Hoeon Kim, Johann Deisenhofer, Linda Yu

Research output: Contribution to journalReview article

17 Scopus citations

Abstract

The cytochrome bc1 complex from bovine heart mitochondria is a multi- functional enzyme complex. In addition to electron and proton transfer activity, the complex also processes an activatable peptidase activity and a superoxide generating activity. The crystal structure of the complex exists as a closely interacting functional dimer. There are 13 transmembrane helices in each monomer, eight of which belong to cytochrome b, and five of which belong to cytochrome c1, Rieske iron-sulfur protein (ISP), subunits 7, 10 and 11, one each. The distances of 21 Å between b(L) heme and b(H) heme and of 27 Å. between b(L) heme and the iron-sulfur cluster (FeS), accommodate well the observed fast electron transfers between the involved redox centers. However, the distance of 31 Å between heme c1 and FeS, makes it difficult to explain the high electron transfer rate between them. 3D structural analyses of the bc1 complexes co-crystallized with the Q0 site inhibitors suggest that the extramembrane domain of the ISP may undergo substantial movement during the catalytic cycle of the complex. This suggestion is further supported by the decreased in the cytochrome bc1 complex activity and the increased in activation energy for mutants with increased rigidity in the neck region of ISP.

Original languageEnglish (US)
Pages (from-to)103-109
Number of pages7
JournalBioFactors
Volume9
Issue number2-4
DOIs
StatePublished - Jan 1 1999

Keywords

  • Mitochondrial processing peptidase
  • Structure of cytochrome bc complex
  • Superoxide
  • Ubiquinol-cytochrome c reductase

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Medicine
  • Clinical Biochemistry

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