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Conformational plasticity in GDAP1's GST-like domain enables thapsic acid recognition
Nicholas T Arredondo1, Michael A DaSilva1, Maya R Brown1
1Department of Biological Sciences, University of Pittsburgh, Pittsburgh PA 15260, USA.
The Journal of Biological Chemistry
|July 28, 2026
Summary
Mitochondrial protein GDAP1 binds lipids in its active site, not a separate pocket. Movements in its alpha-loop and G-site remodel the active site for lipid binding, crucial for cell protection.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Glutathione S-transferase (GST) superfamily proteins detoxify cells using a central active site.
- Mitochondrial GST-like protein GDAP1's function and binding site for thapsic acid were previously unclear.
- A non-canonical binding pocket was proposed for GDAP1, leaving its canonical site's role ambiguous.
Purpose of the Study:
- To biochemically characterize GDAP1 mutants in its canonical domains.
- To determine the precise binding site for thapsic acid in GDAP1.
- To elucidate the role of GDAP1's conformational dynamics in lipid binding and cytoprotection.
Main Methods:
- Site-directed mutagenesis of GDAP1 canonical domains (G-site, H-site, alpha-loop, L-site).
- Biochemical assays to assess thapsic acid binding activity.
- Structural prediction and molecular modeling.
- Evaluation of cytoprotective effects of wild-type and mutant GDAP1.
Main Results:
- Thapsic acid binding occurs within GDAP1's canonical active site, not a non-canonical pocket.
- Mutations in canonical domains, particularly the alpha-loop and G-site, impact thapsic acid binding.
- Alpha-loop and G-site movements remodel the canonical site for lipid interaction.
- Mutants in the canonical active site abolished GDAP1's cytoprotective function.
- An extensive map of lipid-binding residues in GDAP1 was generated.
Conclusions:
- GDAP1 is a conformationally dynamic protein that utilizes its canonical active site for lipid binding.
- Coordinated movements of the alpha-loop and G-site remodel the active site for thapsic acid recognition.
- GDAP1's lipid-binding activity is essential for maintaining mitochondrial membrane integrity and redox homeostasis.
- These findings clarify GDAP1's mechanism of action and its role in cellular protection.
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