Dimers of mitochondrial ATP synthase form the permeability transition pore

• Published in: Proceedings of the National Academy of Sciences - PNAS 2013-04, Vol.110 (15), p.5887-5892
• Main Authors: Giorgio, Valentina, von Stockum, Sophia, Antoniel, Manuela, Fabbro, Astrid, Fogolari, Federico, Forte, Michael, Glick, Gary D., Petronilli, Valeria, Zoratti, Mario, Szabó, Ildikó, Lippe, Giovanna, Bernardi, Paolo
• Format: Article
• Language: English
• Subjects: Adenosine triphosphatase; Animals; Antibodies; Apoptosis; Binding sites; Biological Sciences; Calcium - metabolism; Cattle; Cell death; Cell Line, Tumor; Dimerization; Dimers; Electric current; Humans; Hydrolysis; Ions; Membrane Potentials; Mice; Mitochondria; Mitochondria - metabolism; Mitochondria, Liver - metabolism; Mitochondrial Membrane Transport Proteins - physiology; Mitochondrial Proton-Translocating ATPases - metabolism; Monomers; Oligomycins; Permeability; Physiological regulation; Proteins; Ribonucleic acid; RNA; RNA, Small Interfering - metabolism; Small interfering RNA; Transfection
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1217823110

Here we define the molecular nature of the mitochondrial permeability transition pore (PTP), a key effector of cell death. The PTP is regulated by matrix cyclophilin D (CyPD), which also binds the lateral stalk of the F OF ₁ ATP synthase. We show that CyPD binds the oligomycin sensitivity-conferring protein subunit of the enzyme at the same site as the ATP synthase inhibitor benzodiazepine 423 (Bz-423), that Bz-423 sensitizes the PTP to Ca ²⁺ like CyPD itself, and that decreasing oligomycin sensitivity-conferring protein expression by RNAi increases the sensitivity of the PTP to Ca ²⁺. Purified dimers of the ATP synthase, which did not contain voltage-dependent anion channel or adenine nucleotide translocator, were reconstituted into lipid bilayers. In the presence of Ca ²⁺, addition of Bz-423 triggered opening of a channel with currents that were typical of the mitochondrial megachannel, which is the PTP electrophysiological equivalent. Channel openings were inhibited by the ATP synthase inhibitor AMP-PNP (γ-imino ATP, a nonhydrolyzable ATP analog) and Mg ²⁺/ADP. These results indicate that the PTP forms from dimers of the ATP synthase.