Abstract
The Bcl-2-related survival proteins confer cellular resistance to a wide range of agents. Bcl-xL-expressing hepatocyte cell lines are resistant to tumour necrosis factor and anti-cancer drugs, but are more sensitive than isogenic control cells to antimycin A, an inhibitor of mitochondrial electron transfer. Computational molecular docking analysis predicted that antimycin A interacts with the Bcl-2 homology domain 3 (BH3)-binding hydrophobic groove of Bcl-xL. We demonstrate that antimycin A and a Bak BH3 peptide bind competitively to recombinant Bcl-2. Antimycin A and BH3 peptide both induce mitochondrial swelling and loss of DeltaPsim on addition to mitochondria expressing Bcl-xL. The 2-methoxy derivative of antimycin A3 is inactive as an inhibitor of cellular respiration but still retains toxicity for Bcl-xL+ cells and mitochondria. Finally, antimycin A inhibits the pore-forming activity of Bcl-x L in synthetic liposomes, demonstrating that a small non-peptide ligand can directly inhibit the function of Bcl-2-related proteins.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adenosine Triphosphate / metabolism
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Animals
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Anti-Bacterial Agents / pharmacology*
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Antimycin A / analogs & derivatives
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Antimycin A / pharmacology*
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Apoptosis / drug effects*
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Apoptosis / physiology
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Cell Line
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Flow Cytometry
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Hepatocytes / drug effects
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Hepatocytes / ultrastructure
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Immunoblotting
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Liposomes / metabolism
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Membrane Proteins / metabolism
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Mice
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Mitochondria / drug effects
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Mitochondria / metabolism*
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Mitochondria / ultrastructure
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Mitochondrial Swelling
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Models, Molecular
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Molecular Structure
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Protein Structure, Tertiary
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Proto-Oncogene Proteins c-bcl-2 / antagonists & inhibitors
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Proto-Oncogene Proteins c-bcl-2 / genetics
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Proto-Oncogene Proteins c-bcl-2 / metabolism*
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Recombinant Proteins / metabolism
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Transfection
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bcl-2 Homologous Antagonist-Killer Protein
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bcl-X Protein
Substances
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Anti-Bacterial Agents
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Bak1 protein, mouse
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Bcl2l1 protein, mouse
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Liposomes
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Membrane Proteins
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Proto-Oncogene Proteins c-bcl-2
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Recombinant Proteins
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bcl-2 Homologous Antagonist-Killer Protein
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bcl-X Protein
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Antimycin A
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Adenosine Triphosphate