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Phosphorylation of Cytochrome c Threonine 28 Regulates Electron Transport Chain Activity in Kidney: IMPLICATIONS FOR AMP KINASE.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 2017 Jan 06; Vol. 292 (1), pp. 64-79. Date of Electronic Publication: 2016 Oct 07. - Publication Year :
- 2017
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Abstract
- Mammalian cytochrome c (Cytc) plays a key role in cellular life and death decisions, functioning as an electron carrier in the electron transport chain and as a trigger of apoptosis when released from the mitochondria. However, its regulation is not well understood. We show that the major fraction of Cytc isolated from kidneys is phosphorylated on Thr <superscript>28</superscript> , leading to a partial inhibition of respiration in the reaction with cytochrome c oxidase. To further study the effect of Cytc phosphorylation in vitro, we generated T28E phosphomimetic Cytc, revealing superior behavior regarding protein stability and its ability to degrade reactive oxygen species compared with wild-type unphosphorylated Cytc Introduction of T28E phosphomimetic Cytc into Cytc knock-out cells shows that intact cell respiration, mitochondrial membrane potential (ΔΨ <subscript>m</subscript> ), and ROS levels are reduced compared with wild type. As we show by high resolution crystallography of wild-type and T28E Cytc in combination with molecular dynamics simulations, Thr <superscript>28</superscript> is located at a central position near the heme crevice, the most flexible epitope of the protein apart from the N and C termini. Finally, in silico prediction and our experimental data suggest that AMP kinase, which phosphorylates Cytc on Thr <superscript>28</superscript> in vitro and colocalizes with Cytc to the mitochondrial intermembrane space in the kidney, is the most likely candidate to phosphorylate Thr <superscript>28</superscript> in vivo We conclude that Cytc phosphorylation is mediated in a tissue-specific manner and leads to regulation of electron transport chain flux via "controlled respiration," preventing ΔΨ <subscript>m</subscript> hyperpolarization, a known cause of ROS and trigger of apoptosis.<br /> (© 2017 by The American Society for Biochemistry and Molecular Biology, Inc.)
- Subjects :
- Adenylate Kinase chemistry
Animals
Apoptosis
Crystallography, X-Ray
Cytochromes c chemistry
Electron Transport
Electron Transport Complex IV chemistry
Kidney cytology
Membrane Potential, Mitochondrial
Mice
Mitochondria metabolism
Oxidation-Reduction
Phosphorylation
Protein Conformation
Reactive Oxygen Species metabolism
Adenylate Kinase metabolism
Cell Respiration physiology
Cytochromes c metabolism
Electron Transport Complex IV metabolism
Kidney metabolism
Threonine metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1083-351X
- Volume :
- 292
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 27758862
- Full Text :
- https://doi.org/10.1074/jbc.M116.744664