Multiprotein complex containing succinate dehydrogenase confers mitochondrial ATP-sensitive K+ channel activity

Area of Science:

• Mitochondrial biology
• Cardioprotection
• Molecular structure

Background:

• The mitochondrial ATP-sensitive K(+) (mitoK(ATP)) channel protects cardiac and neuronal cells from ischemia and apoptosis.
• Its molecular structure remains unknown, with ongoing debate about whether mitoK(ATP) or succinate dehydrogenase (SDH) is the true target of cardioprotective drugs.

Purpose of the Study:

• To elucidate the molecular structure and function of the mitoK(ATP) channel.
• To resolve the controversy regarding the target of cardioprotective drugs in ischemic preconditioning.

Main Methods:

• Investigated the association of SDH with other mitochondrial proteins, including mABC1, phosphate carrier, adenine nucleotide translocator, and ATP synthase.
• Reconstituted a purified inner mitochondrial fraction containing these proteins into proteoliposomes and lipid bilayers.
• Assessed channel activity using mitoK(ATP) activators, blockers, and SDH inhibitors.

Main Results:

• Demonstrated that SDH forms a functional and structural component of the mitoK(ATP) channel.
• Identified a macromolecular supercomplex involving SDH and other key mitochondrial proteins.
• Confirmed that the reconstituted channel activity is modulated by both mitoK(ATP) and SDH modulators.

Conclusions:

• SDH is an integral part of the mitoK(ATP) channel, resolving the debate over its role in ischemic preconditioning.
• This finding provides crucial insights into the structural basis of mitoK(ATP) channels and potential drug targets for cardioprotection.