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ALTERNATIVE OXIDASE: From Gene to Function
Greg C. Vanlerberghe1, Lee McIntosh
1Department of Botany and Division of Life Science, University of Toronto at Scarborough, 1265 Military Trail, Scarborough, Ontario M1C 1A4, Canada, Department of Energy Plant Research Laboratory and Biochemistry Department, Michigan State University, East Lansing, Michigan 48824.
Annual Review of Plant Physiology and Plant Molecular Biology
|June 1, 1997
Summary
Plants, fungi, and protists use an alternative oxidase pathway for respiration, especially under stress. This cyanide-resistant pathway helps balance cellular energy production when the main pathway is disrupted.
Area of Science:
- Biochemistry
- Plant Physiology
- Mitochondrial Respiration
Background:
- Many organisms possess a cyanide-resistant, alternative mitochondrial respiratory pathway.
- This pathway involves the alternative oxidase (Aox1) and branches at the ubiquinone pool.
- It is linked to proton translocation only at Complex 1 (NADH dehydrogenase).
Purpose of the Study:
- To explore the regulation and function of the alternative respiratory pathway.
- To understand how alternative oxidase expression and activity are controlled.
- To elucidate the role of this pathway in balancing cellular metabolism under stress.
Main Methods:
- Investigated gene expression of the alternative oxidase (Aox1).
- Examined posttranslational modifications of the alternative oxidase.
- Analyzed the influence of stress stimuli and carbon availability on respiration.
Main Results:
- Alternative oxidase expression is induced by stress (cold, oxidative stress, pathogens) and restricted electron flow.
- Control occurs at both gene expression and posttranslational levels.
- Activation involves reversible covalent modification and specific carbon metabolites.
Conclusions:
- The alternative respiratory pathway provides a crucial mechanism for balancing cellular energy metabolism.
- It responds dynamically to environmental and metabolic cues.
- This pathway is essential for maintaining cellular function when the cytochrome pathway is compromised.