Regulation by Magnesium of Potato Tuber Mitochondrial Respiratory Activities

Vicente, Joaquim A.F.; Madeira, Vı́tor M.C.; Vercesi, Anı́bal E.

doi:10.1007/s10863-004-8999-x

Cited by 3 publications

(1 citation statement)

References 35 publications

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“…5B). This concentration is also relatively close to the 4 mM reported in potato tuber mitochondria from succinate-and α-ketoglutarateMg 2+ -dependent respiration measurements (21). Of course, the possibility that some amount of Mg 2+ is lost during mitochondrial preparation cannot be excluded.…”

Section: Measurement Of Nucleotides From Cell Extracts and Adp Homeossupporting

confidence: 83%

Interplay of Mg ²⁺ , ADP, and ATP in the cytosol and mitochondria: Unravelling the role of Mg ²⁺ in cell respiration

Gout

Rébeillé

Douce

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

185

156

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In animal and plant cells, the ATP/ADP ratio and/or energy charge are generally considered key parameters regulating metabolism and respiration. The major alternative issue of whether the cytosolic and mitochondrial concentrations of ADP and ATP directly mediate cell respiration remains unclear, however. In addition, because only free nucleotides are exchanged by the mitochondrial ADP/ATP carrier, whereas MgADP is the substrate of ATP synthase (EC 3.6.3.14) ] reversibly increases free nucleotide concentration in the cytosol and matrix, enhances ADP at the expense of ATP, decreases coupled respiration, and stops cell growth. We conclude that the cytosolic ADP concentration, and not ATP, ATP/ADP ratio, or energy charge, controls the respiration of plant cells. The Mg 2+ concentration, remarkably constant and low in the cytosol and tenfold higher in the matrix, mediates ADP/ATP exchange between the cytosol and matrix, [MgADP]-dependent mitochondrial ATP synthase activity, and cytosolic free ADP homeostasis. MgATP is the substrate of numerous phosphorylating enzymes and the principal energy source of the cell. Indeed, any increase in metabolic activity increases the rate of MgATP use and, consequently, the rate of ADP and magnesium release, and vice versa. In normoxia, the MgATP concentration should be essentially balanced by the ADP phosphorylation catalyzed by mitochondrial ATP synthase, thereby adjusting oxidative phosphorylation to cell ATP needs. The ADP/ATP carrier (AAC) of the inner mitochondrial membrane, which exchanges free nucleotides, and adenylate kinase (EC 2.7.4.3), which interconverts MgADP and free ADP with MgATP and free AMP in the presence of Mg 2+ (7), participate in this regulation (reviewed in ref. 8). Clearly, to better understand the interplay of free and Mg-complexed ADP and ATP in the regulation of cell respiration it is necessary to know their concentrations, as well as the concentration of Mg 2+ in the cytosol and mitochondrial matrix.Nucleotides can be measured using ] (13). We adapted this noninvasive technique to the simultaneous in vivo measurement of cytosolic and mitochondrial Mg 2+ and free/Mgcomplexed nucleotides concentrations in culture cells.We used homogenous cells cultivated on liquid nutrient media (NM) so as to narrow resonance peaks on in vivo NMR spectra, thus improving the signal-to-noise ratios and the accuracy of chemical shift measurements and limiting peak overlaps. In addition, the heterotrophic sycamore (Acer pseudoplatanus L.) cells of cambial origin used in this study contain no large chloroplasts, but only small plastids (14, 15) with low amounts of nucleotides (16), thus permitting more precise measurement of the cytosolic and mitochondrial nucleotide pools. SignificanceThe respiration of heterotrophic cells, where most of the ATP demand is met by mitochondrial oxidative phosphorylation, is generally thought to be regulated either by the ATP/ADP ratio and/or energy charge or by nucleotide concentration. The way in which ADP and ATP may directly mediate respirat...

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Section: Measurement Of Nucleotides From Cell Extracts and Adp Homeossupporting

confidence: 83%

Interplay of Mg ²⁺ , ADP, and ATP in the cytosol and mitochondria: Unravelling the role of Mg ²⁺ in cell respiration

Gout

Rébeillé

Douce

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

185

156

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Regulation of Respiration by Cellular Key Parameters: Energy Demand, ADP, and Mg2+

Bligny¹,

Gout²

2017

Advances in Photosynthesis and Respiration

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Channels and transporters for inorganic ions in plant mitochondria: Prediction and facts

Vothknecht

Szabó

2020

Mitochondrion

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Regulation by Magnesium of Potato Tuber Mitochondrial Respiratory Activities

Cited by 3 publications

References 35 publications

Interplay of Mg ²⁺ , ADP, and ATP in the cytosol and mitochondria: Unravelling the role of Mg ²⁺ in cell respiration

Interplay of Mg ²⁺ , ADP, and ATP in the cytosol and mitochondria: Unravelling the role of Mg ²⁺ in cell respiration

Regulation of Respiration by Cellular Key Parameters: Energy Demand, ADP, and Mg2+

Channels and transporters for inorganic ions in plant mitochondria: Prediction and facts

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Regulation by Magnesium of Potato Tuber Mitochondrial Respiratory Activities

Cited by 3 publications

References 35 publications

Interplay of Mg 2+ , ADP, and ATP in the cytosol and mitochondria: Unravelling the role of Mg 2+ in cell respiration

Interplay of Mg 2+ , ADP, and ATP in the cytosol and mitochondria: Unravelling the role of Mg 2+ in cell respiration

Regulation of Respiration by Cellular Key Parameters: Energy Demand, ADP, and Mg2+

Channels and transporters for inorganic ions in plant mitochondria: Prediction and facts

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Interplay of Mg ²⁺ , ADP, and ATP in the cytosol and mitochondria: Unravelling the role of Mg ²⁺ in cell respiration

Interplay of Mg ²⁺ , ADP, and ATP in the cytosol and mitochondria: Unravelling the role of Mg ²⁺ in cell respiration