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Biochemical and structural characterization of a superoxide dismutase-containing respiratory supercomplex from Mycobacterium smegmatis
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
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(English)Manuscript (preprint) (Other academic)
National Category
Biochemistry and Molecular Biology
Research subject
Biochemistry
Identifiers
URN: urn:nbn:se:su:diva-158717OAI: oai:DiVA.org:su-158717DiVA, id: diva2:1238646
Available from: 2018-08-14 Created: 2018-08-14 Last updated: 2018-10-24Bibliographically approved
In thesis
1. Wiring Components of the Respiratory Chain: Modulation of the Respiratory Chain in Yeast and Bacteria
Open this publication in new window or tab >>Wiring Components of the Respiratory Chain: Modulation of the Respiratory Chain in Yeast and Bacteria
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The enzyme complexes of the respiratory chain are organized in supramolecular assemblies, so-called respiratory supercomplexes. In the yeast Saccharomyces cerevisiae, these supercomplexes consist of two copies of complex III (bc1 complex) and one or two copies of complex IV (cytochrome c oxidase, CytcO). Several factors, including lipids and small proteins, have been identified to facilitate or stabilize this organization.

Respiratory supercomplex factor (Rcf) 1 interacts with CytcO. In this work, we show that in the native S. cerevisiae mitochondrial membrane several forms of CytcO co-exist. Intact CytcO shows spectral and functional properties similar to those of CytcOs from other organisms characterized earlier. A second population displayed a lower midpoint potential of heme a3 as well as accelerated ligand binding, suggesting structural differences around the catalytic site. Severe structural changes of the catalytic site and the overall structure of the enzyme were found in a third population of CytcO. The fraction of the structurally altered CytcO increased upon removal of Rcf1. Here, a mechanism is proposed in which Rcf1 regulates function of the CytcO by altering the catalytic site so that electron transfer between heme a and heme a3 is slowed, resulting in a more exergonic O2-ligand binding. This scenario would in turn increase heat production on the expense of the proton electrochemical gradient.

Rcf1 was further shown to facilitate electron transfer from the bc1 complex to CytcO in a supercomplex by interacting with the electron carrier cytochrome c (cyt. c).

In addition, we purified and structurally and functionally characterized the supercomplex of Mycobacterium smegmatis, which contains a membrane-anchored cyt. c as a subunit of the bcc1 complex.

Place, publisher, year, edition, pages
Stockholm: Department of Biochemistry and Biophysics, Stockholm University, 2018. p. 76
Keywords
Cytochrome c oxidase, Electron transfer, Membrane protein, Ligand, Kinetics, Mechanism, Rcf1, Cytochrome c, Respiratory supercomplex, Cryo-electron microscopy
National Category
Biochemistry and Molecular Biology
Research subject
Biochemistry
Identifiers
urn:nbn:se:su:diva-158733 (URN)978-91-7797-370-6 (ISBN)978-91-7797-371-3 (ISBN)
Public defence
2018-09-28, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Available from: 2018-09-05 Created: 2018-08-14 Last updated: 2018-08-29Bibliographically approved

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