title: Modulation of the respiratory supercomplexes in yeast: enhanced formation of cytochrome oxidase increases the stability and abundance of respiratory supercomplexes.
abstract: Yeast cells deficient in the Rieske iron-sulfur subunit (Rip1) of ubiquinol-cytochrome c reductase (bc1) accumulate a late core assembly intermediate, which weakly associates with cytochrome oxidase (CcO) in a respiratory supercomplex. Expression of the N-terminal half of Rip1, which lacks the C-terminal FeS-containing globular domain (designated N-Rip1), results in a marked stabilization of trimeric and tetrameric bc1-CcO supercomplexes. Another bc1 mutant (qcr9Δ) stalled at the same assembly intermediate is likewise converted to stable supercomplex species by the expression of N-Rip1, but not by expression of intact Rip1. The N-Rip1-induced stabilization of bc1-CcO supercomplexes is independent of the Bcs1 translocase, which mediates Rip1 translocation during bc1 biogenesis. N-Rip1 induces the stabilization of bc1-CcO supercomplexes through an enhanced formation of CcO. The association of N-Rip1 with the late core bc1 assembly intermediate appears to confer stabilization of a CcO assembly intermediate. This induced stabilization of CcO is dependent on the Rcf1 supercomplex stabilization factor and only partially dependent on the presence of cardiolipin. N-Rip1 exerts a related induction of CcO stabilization in WT yeast, resulting in enhanced respiration. Additionally, the impact of CcO stabilization on supercomplexes was observed by means other than expression of N-Rip1 (via overexpression of CcO subunits Cox4 and Cox5a), demonstrating that this is a general phenomenon. This study presents the first evidence showing that supercomplexes can be stabilized by the stimulated formation of CcO.
authors.affiliation: From the Departments of Medicine and Biochemistry, University of Utah Health Sciences Center, Salt Lake City, Utah 84132 and.
authors.forename: Tie-Zhong
authors.initials: TZ
authors.lastname: Cui
authors.forename: Annalea
authors.initials: A
authors.lastname: Conte
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Fox
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Zara
authors.forename: Dennis R
authors.initials: DR
authors.lastname: Winge
mesh_terms: D004579:Electron Transport / Q000502:physiology; D003576:Electron Transport Complex IV / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability / Q000502:physiology; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D003576:Electron Transport Complex IV
keywords: Bioenergetics/Electron Transfer Complex; Cardiolipin; Cytochrome Oxidase; Mitochondria; Mitochondrial Metabolism