Journal
JOURNAL OF BIOLOGICAL CHEMISTRY
Volume 289, Issue 19, Pages 13259-13272Publisher
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M113.542910
Keywords
Genetics; Metalloprotease; Mitochondria; Oxidative Stress; Yeast; Mitochondrial Stress; Oma1; Proteases
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Funding
- National Institutes of Health [P20 RR-017675, P30GM103335, ES03817]
- University of Nebraska-Lincoln Lyman Award
- University of Nebraska UCARE program
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Background: Oma1 is a conserved membrane-bound protease that forms a high molecular mass complex. Results: Oma1 activity is induced by stress stimuli and required for survival. The activation is linked to changes in Oma1 oligomer stability and involves its C-terminal region. Conclusion: Oma1 function is activated by mitochondrial stress and is important for stress tolerance. Significance: Novel insights into Oma1 function and a potential stress activation mechanism are provided. Functional integrity of mitochondria is critical for optimal cellular physiology. A suite of conserved mitochondrial proteases known as intramitochondrial quality control represents one of the mechanisms assuring normal mitochondrial function. We previously demonstrated that ATP-independent metalloprotease Oma1 mediates degradation of hypohemylated Cox1 subunit of cytochrome c oxidase and is active in cytochrome c oxidase-deficient mitochondria. Here we show that Oma1 is important for adaptive responses to various homeostatic insults and preservation of normal mitochondrial function under damage-eliciting conditions. Changes in membrane potential, oxidative stress, or chronic hyperpolarization lead to increased Oma1-mediated proteolysis. The stress-triggered induction of Oma1 proteolytic activity appears to be associated with conformational changes within the Oma1 homo-oligomeric complex, and these alterations likely involve C-terminal residues of the protease. Substitutions in the conserved C-terminal region of Oma1 impair its ability to form a labile proteolytically active complex in response to stress stimuli. We demonstrate that Oma1 genetically interacts with other inner membrane-bound quality control proteases. These findings indicate that yeast Oma1 is an important player in IM protein homeostasis and integrity by acting in concert with other intramitochondrial quality control components.
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