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Modulation of O-2 reduction in Saccharomyces cerevisiae mitochondria
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Number of Authors: 22017 (English)In: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 591, no 24, p. 4049-4055Article in journal (Refereed) Published
Abstract [en]

Respiratory supercomplex factor (Rcf) 1 is a membrane-bound protein that modulates the activity of cytochrome c oxidase (CytcO) in Saccharomycescerevisiae mitochondria. To investigate this regulatory mechanism, we studied the interactions of CytcO with potassium cyanide (KCN) upon removal of Rcf Delta. While the addition of KCN to the wild-type mitochondria results in a full reduction of heme a, with the rcf Delta mitochondria, a significant fraction remains oxidized. Upon addition of ascorbate in the presence of O-2 and KCN, the reduction level of hemes a and b was a factor of similar to 2 larger with the wild-type than with the rcf Delta mitochondria. These data indicate that turnover of CytcO was less blocked in rcf Delta than in the wild-type mitochondria, suggesting that Rcf Delta modulates the structure of the catalytic site.

Place, publisher, year, edition, pages
2017. Vol. 591, no 24, p. 4049-4055
Keywords [en]
cytochrome aa(3), cytochrome c oxidase, electron transfer, membrane protein, respiratory supercomplex factor, Saccharomy cescerevisiae
National Category
Biochemistry and Molecular Biology
Research subject
Biochemistry
Identifiers
URN: urn:nbn:se:su:diva-152520DOI: 10.1002/1873-3468.12918ISI: 000418825700008PubMedID: 29171870OAI: oai:DiVA.org:su-152520DiVA, id: diva2:1180474
Available from: 2018-02-05 Created: 2018-02-05 Last updated: 2018-10-31Bibliographically approved
In thesis
1. Modulators of Saccharomyces cerevisiae cytochrome c oxidase: Implications for the regulation of mitochondrial respiration
Open this publication in new window or tab >>Modulators of Saccharomyces cerevisiae cytochrome c oxidase: Implications for the regulation of mitochondrial respiration
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Oxidative phosphorylation in mitochondria is performed by enzyme complexes and electron carriers that reside in the inner membrane. It is now generally accepted that these respiratory enzyme complexes assemble into larger so-called supercomplexes. However, it is presently not known why, under which conditions or how these supercomplexes form.

A number of factors of particular importance for the formation of supercomplexes have been identified, such as the Respiratory supercomplex factors (Rcf1 and Rcf2) and cardiolipin. The work presented in this thesis is focused on the characterization of cytochrome c oxidase (CytcO) in mitochondria from Saccharomyces cerevisiae strains in which these components have been removed, with a particular focus on Rcf1. First, we concluded that Rcf1 has an impact on the activity and ligand binding kinetics of CytcO, which upon genetic deletion of rcf1 leads to formation of sub-populations of CytcO with different functionality. Second, we noted that the ability of CytcO to oxidize cytochrome c (cyt. c) depends on the presence of Rcf1. Further, we observed that while CytcO in wild-type mitochondria displayed differences in the oxidation kinetics of cyt. c from horse heart or S. cerevisiae, with the Δrcf1 mitochondria these differences were lost. This observation suggested that Rcf1 interacts with cyt. c. Furthermore, the data showed that in CytcO from Δrcf1 mitochondria heme a3 was altered while heme a was intact.

Using proteo-liposomes of different lipid composition and size we also investigated the influence of lipid head groups on the coupled activity of a quinol oxidase and ATP-synthase. Specifically, we addressed the question if protons are transferred between proton “producers” and “consumers” via lateral proton transfer along the membrane surface or via bulk water. Our data supported the principle of lateral proton transfer.

Lastly, we characterized the ligand binding of yeast flavohemoglobin and concluded that the flavohemoglobin has a population that resides in the intermembrane space of mitochondria, not only in matrix and cytosol as previously suggested.

Place, publisher, year, edition, pages
Stockholm: Department of Biochemistry and Biophysics, Stockholm University, 2018. p. 48
Keywords
cytochrome c oxidase, cytochrome c, OXPHOS, membrane protein, kinetics, ligand-binding, electron transfer, Rcf1, respiratory supercomplexes, Saccharomyces cerevisiae
National Category
Biochemistry and Molecular Biology
Research subject
Biochemistry
Identifiers
urn:nbn:se:su:diva-161515 (URN)978-91-7797-457-4 (ISBN)978-91-7797-456-7 (ISBN)
Public defence
2018-12-13, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (English)
Opponent
Supervisors
Available from: 2018-11-20 Created: 2018-10-29 Last updated: 2018-11-13Bibliographically approved

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