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Coupling/Uncoupling Reversibility in Isolated Mitochondria from Saccharomyces cerevisiae
Lilia Morales-García1,2, Carolina Ricardez-García1, Paulina Castañeda-Tamez1
1Department of Genetics and Molecular Biology, Instituto de Fisiología Celular, UNAM, Mexico City 04510, Mexico.
Life (Basel, Switzerland)
|December 24, 2021
Summary
Mitochondrial unspecific pore (MUC) in yeast opens with high ATP/ADP ratios and closes with calcium, regulating oxidative phosphorylation. MUC closure increases reactive oxygen species (ROS) when ATP synthesis is absent.
Area of Science:
- Cellular respiration
- Mitochondrial function
- Yeast metabolism
Background:
- Saccharomyces cerevisiae relies on fermentation but uses the respiratory chain to regenerate NADH for Glyceraldehyde-3-phosphate activity.
- Oxidative phosphorylation (OxPhos) uncoupling, regulated by the mitochondrial unspecific pore (MUC), favors fermentation.
- MUC opening/closing is influenced by ATP/ADP ratio and calcium ions ([Ca2+]), affecting OxPhos coupling.
Purpose of the Study:
- To investigate the opening and closing dynamics of the MUC in isolated Saccharomyces cerevisiae mitochondria.
- To determine the influence of varying ATP/ADP ratios and [Ca2+] on MUC activity.
- To assess the impact of MUC state on mitochondrial oxygen consumption, swelling, membrane potential, and ROS generation.
Main Methods:
- Isolated mitochondria from Saccharomyces cerevisiae were used.
- Experiments involved varying incubation times, ATP/ADP ratios, and [Ca2+].
- Measurements included oxygen consumption rates, mitochondrial swelling, transmembrane potential, and reactive oxygen species (ROS) generation.
Main Results:
- MUC opening was observed to be reversible.
- A high ATP/ADP ratio promoted MUC opening.
- [Ca2+] induced MUC closure, even after prolonged opening, and closure led to increased ROS in the absence of ATP synthesis.
Conclusions:
- The mitochondrial unspecific pore (MUC) in Saccharomyces cerevisiae is dynamically regulated by cellular energy status (ATP/ADP ratio) and calcium ions.
- MUC plays a crucial role in controlling oxidative phosphorylation coupling.
- MUC closure under conditions of no ATP synthesis leads to elevated ROS production, highlighting a potential link between MUC regulation and oxidative stress.
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