Deletion of subunit 9 of the Saccharomyces cerevisiae cytochrome bc₁ complex specifically impairs electron transfer at the ubiquinol oxidase site (center P) in the bc₁ complex

Abstract

Deletion of QcRg, the nuclear gene encoding subunit 9 of the mitochondrial cytoehromc bc, complex in Saccharono,ces cerevisiae, results in inactivation of the bc~ complex and inabillity of the yeast to grow on non-fermentable carbon sources. The loss of bet complex activity is due to loss of electron transfer activity at the ubiquinol oxidase site (center P) in the complex. Electron transfer at the abiquinone reductas¢ site (center N), is unaffected by the lo~s of subunit 9, but the extent of ¢ytochrome b reduction is diminished. This is the first instance in which a supernumerary polypeptide, lacking a redox prosthetic group, laas been shown to be required for an electron transfer reaction within the cytoehrome bc~ complex.

Macrophage mitochondrial bioenergetics and tissue invasion are boosted by an Atossa‐Porthos axis in Drosophila

“…Orthologs of Porthos’ mitochondrial targets affect many aspects of the organelle’s function, from its specialized translation, its import of proteins and their insertion into the inner membrane where the ETC resides, the formation of this inner membrane which can affect ATP production (Brandt et al , 2017 ), and its import of fatty acids as fuel. We also identify as targets accessory subunits of the ETC’s OxPhos complexes, which are involved in enhancing complex function (Graham et al , 1992 ; Phillips et al , 1993 ) as well as proteins affecting these complexes’ assembly or dimerization (Davies et al , 2011 ; Dennerlein et al , 2015 ; Formosa et al , 2015 ; Hahn et al , 2016 ). Thus, the enhanced OxPhos we detected in the presence of Porthos in our mitochondrial assay could result from improved efficiency through multiple avenues: increases in the activity, amount, localization, and assembly of OxPhos components as well as the extent of the membrane folds in which they are localized.…”

The LYR Protein Mzm1 Functions in the Insertion of the Rieske Fe/S Protein in Yeast Mitochondria

“…1) (3, 38). In contrast, Qcr9 is one of the last subunits added during the assembly process and, much like Mzm1, is critical only for bc 1 function at 37°C (12,28). Mitochondria isolated from yeast lacking either Qcr7 or Qcr9 were used for quantitation of total zinc by ICP-OES and of labile zinc with the RhodZin-3 fluorophore.…”

A Protein Complex Containing Mdm10p, Mdm12p, and Mmm1p Links Mitochondrial Membranes and DNA to the Cytoskeleton-based Segregation Machinery

“…These cells, which have wild-type mtDNA but no respiratory activity (Graham et al, 1992), show normal mitochondrial morphology and normal velocity of mitochondrial movement ( Figure 8A, j-l; and B).…”