Question:
The antibiotic oligomycin inhibits the oxidative phosphorylation by which of the following mechanisms?
The antibiotic oligomycin inhibits the oxidative phosphorylation by which of the following mechanisms?
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The "o" in the \(F_o\) subunit actually stands for "oligomycin-sensitive." This historical nomenclature makes it easy to remember that oligomycin targets the \(F_o\) component of the ATP synthase complex.
Updated On: Aug 7, 2026
- By binding and blocking \(F_o\) component of the mitochondrial ATP synthase complex
- By binding and blocking \(F_1\) component of the mitochondrial ATP synthase complex.
- By inactivating both the \(F_o\) and \(F_1\) components of the ATP Synthase.
- By collapsing the proton motive force
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The Correct Option is A
Solution and Explanation
Step 1: Understanding the Concept:
Oxidative phosphorylation in mitochondria couples the transfer of electrons through the electron transport chain with the synthesis of ATP by the \(F_oF_1\)-ATP synthase complex.
Inhibitors of this process can target either the electron carriers or the ATP synthase complex directly.
Step 2: Detailed Explanation:
The mitochondrial ATP synthase is a multi-subunit complex composed of two main functional domains:
1. \(F_1\) subunit: A peripheral, hydrophilic protein complex protruding into the mitochondrial matrix that contains the catalytic sites for ATP synthesis.
2. \(F_o\) subunit: An oligomycin-sensitive, hydrophobic transmembrane protein complex embedded in the inner mitochondrial membrane that forms the proton channel.
Mechanism of Oligomycin:
Oligomycin is a macrolide antibiotic that binds specifically to the stalk of the \(F_o\) subunit (specifically to the 'a' subunit or the oligomycin-sensitivity-conferring protein, OSCP).
By binding to \(F_o\), oligomycin physically blocks the proton channel, preventing the flow of protons (\(\text{H}^+\)) from the intermembrane space back into the matrix.
Since proton trans-location through \(F_o\) is required to drive the rotational catalysis of the \(F_1\) subunit, blocking \(F_o\) completely halts ATP synthesis.
Therefore, oligomycin acts by binding and blocking the \(F_o\) component.
Step 3: Final Answer:
Oligomycin inhibits ATP synthesis by blocking the \(F_o\) channel, which corresponds to option (A).
Oxidative phosphorylation in mitochondria couples the transfer of electrons through the electron transport chain with the synthesis of ATP by the \(F_oF_1\)-ATP synthase complex.
Inhibitors of this process can target either the electron carriers or the ATP synthase complex directly.
Step 2: Detailed Explanation:
The mitochondrial ATP synthase is a multi-subunit complex composed of two main functional domains:
1. \(F_1\) subunit: A peripheral, hydrophilic protein complex protruding into the mitochondrial matrix that contains the catalytic sites for ATP synthesis.
2. \(F_o\) subunit: An oligomycin-sensitive, hydrophobic transmembrane protein complex embedded in the inner mitochondrial membrane that forms the proton channel.
Mechanism of Oligomycin:
Oligomycin is a macrolide antibiotic that binds specifically to the stalk of the \(F_o\) subunit (specifically to the 'a' subunit or the oligomycin-sensitivity-conferring protein, OSCP).
By binding to \(F_o\), oligomycin physically blocks the proton channel, preventing the flow of protons (\(\text{H}^+\)) from the intermembrane space back into the matrix.
Since proton trans-location through \(F_o\) is required to drive the rotational catalysis of the \(F_1\) subunit, blocking \(F_o\) completely halts ATP synthesis.
Therefore, oligomycin acts by binding and blocking the \(F_o\) component.
Step 3: Final Answer:
Oligomycin inhibits ATP synthesis by blocking the \(F_o\) channel, which corresponds to option (A).
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