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Citrate and succinate uptake by potato mitochondria
1Department of Biology and Molecular Biology Institute, University of California, Los Angeles, California 90024.
Plant Physiology
|April 1, 1979
Summary
Potato mitochondria uptake citrate and succinate via mechanisms similar to mammalian mitochondria. Energy-dependent processes, particularly inorganic phosphate, are crucial for efficient substrate accumulation, impacting respiration rates.
Area of Science:
- Biochemistry
- Plant Physiology
- Mitochondrial Function
Background:
- Mitochondrial substrate uptake is essential for cellular respiration.
- Understanding plant mitochondrial transport mechanisms is key to optimizing energy metabolism.
- Citrate and succinate are vital metabolic intermediates.
Purpose of the Study:
- To investigate the uptake mechanisms of [(14)C]citrate and [(14)C]succinate in potato (Solanum tuberosum var. Russet Burbank) mitochondria.
- To compare these mechanisms with those in mammalian mitochondria.
- To identify factors influencing substrate accumulation and their impact on respiration.
Main Methods:
- Utilized cellulose pore filtration to study substrate uptake in isolated potato mitochondria.
- Employed radiolabeled citrate and succinate for quantitative analysis.
- Investigated the effects of various inhibitors, energy sources, and reaction conditions on substrate accumulation.
Main Results:
- Potato mitochondria exhibit similar citrate and succinate uptake mechanisms to mammalian mitochondria.
- Uptake is low in the absence of respiration but significantly increases with inorganic phosphate, dicarboxylic acids, and NADH.
- Inhibitors of respiration, exchange carriers, and proton motive force reduce substrate accumulation.
- 1,2,3-benzenetricarboxylic acid, a citrate carrier inhibitor in animals, did not inhibit potato mitochondrial citrate uptake.
- ADP phosphorylation and oligomycin reduced citrate uptake, indicating energy dependence.
- Increased sucrose concentration inhibited initial succinate uptake.
Conclusions:
- Potato mitochondrial substrate uptake, particularly for citrate and succinate, is largely energy-dependent and mediated by specific carriers.
- Limited substrate uptake due to energy-dependent accumulation can lead to depressed initial state 3 respiration rates.
- The identified mechanisms highlight the intricate regulation of mitochondrial metabolism in plants.
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