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Author Spotlight: Advancing Mitochondrial Research - mtHyper7 Biosensor for Subcellular Analysis
Published on: June 2, 2023
Mechanism of oxidative inactivation of human presequence protease by hydrogen peroxide
Jue Chen1, Pedro Filipe Teixeira2, Elzbieta Glaser2
1Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, Bethesda, MD 20892, USA.
Abstract:
The mitochondrial presequence protease (PreP) is a member of the pitrilysin class of metalloproteases. It degrades the mitochondrial targeting presequences of mitochondria-localized proteins as well as unstructured peptides such as amyloid-β peptide. The specific activity of PreP is reduced in Alzheimer patients and animal models of Alzheimer disease. The loss of activity can be mimicked in vitro by exposure to oxidizing conditions, and indirect evidence suggested that inactivation was due to methionine oxidation. We performed peptide mapping analyses to elucidate the mechanism of inactivation. None of the 24 methionine residues in recombinant human PreP was oxidized. We present evidence that inactivation is due to oxidation of cysteine residues and consequent oligomerization through intermolecular disulfide bonds. The most susceptible cysteine residues to oxidation are Cys34, Cys112, and Cys119. Most, but not all, of the activity loss is restored by the reducing agent dithiothreitol. These findings elucidate a redox mechanism for regulation of PreP and also provide a rational basis for therapeutic intervention in conditions characterized by excessive oxidation of PreP.
Insights
Oxidative stress inactivates mitochondrial presequence protease (PreP) by oxidizing cysteine residues, leading to enzyme oligomerization. This discovery offers a new therapeutic target for conditions involving PreP dysfunction, such as Alzheimer's disease.
Area of Science:
- Biochemistry
- Molecular Biology
- Neuroscience
Background:
- Mitochondrial presequence protease (PreP) is a metalloprotease involved in protein processing.
- PreP activity is diminished in Alzheimer's disease models.
- Oxidative stress is implicated in PreP dysfunction.
Purpose of the Study:
- To elucidate the mechanism of PreP inactivation under oxidizing conditions.
- To identify the specific residues responsible for oxidative inactivation.
- To explore potential therapeutic interventions for PreP dysfunction.
Main Methods:
- Peptide mapping analyses of recombinant human PreP.
- In vitro assays to assess enzyme activity.
- Treatment with reducing agents like dithiothreitol.
Main Results:
- Inactivation is not due to methionine oxidation as previously suspected.
- Oxidation of cysteine residues (Cys34, Cys112, Cys119) causes inactivation.
- Inactivation results from intermolecular disulfide bond formation and oligomerization.
- Activity loss is partially reversible with dithiothreitol.
Conclusions:
- PreP inactivation is mediated by cysteine oxidation and subsequent oligomerization.
- This reveals a novel redox-based regulatory mechanism for PreP.
- Findings provide a basis for therapeutic strategies targeting PreP oxidation in diseases like Alzheimer's.
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