Department of Biomedical Sciences, University of Padova, 35131, Padova, Italy.
Consiglio Nazionale delle Ricerche Neuroscience Institute, 35131, Padova, Italy.
Nat Commun. 2019 Sep 25;10(1):4341. doi: 10.1038/s41467-019-12331-1.
The molecular identity of the mitochondrial megachannel (MMC)/permeability transition pore (PTP), a key effector of cell death, remains controversial. By combining highly purified, fully active bovine F-ATP synthase with preformed liposomes we show that Ca dissipates the H gradient generated by ATP hydrolysis. After incorporation of the same preparation into planar lipid bilayers Ca elicits currents matching those of the MMC/PTP. Currents were fully reversible, were stabilized by benzodiazepine 423, a ligand of the OSCP subunit of F-ATP synthase that activates the MMC/PTP, and were inhibited by Mg and adenine nucleotides, which also inhibit the PTP. Channel activity was insensitive to inhibitors of the adenine nucleotide translocase (ANT) and of the voltage-dependent anion channel (VDAC). Native gel-purified oligomers and dimers, but not monomers, gave rise to channel activity. These findings resolve the long-standing mystery of the MMC/PTP and demonstrate that Ca can transform the energy-conserving F-ATP synthase into an energy-dissipating device.
线粒体巨大通道（MMC）/通透性转换孔（PTP）是细胞死亡的关键效应因子，其分子身份一直存在争议。通过将高度纯化、完全活性的牛 F-ATP 合酶与预形成的脂质体结合，我们发现 Ca2+ 会耗散由 ATP 水解产生的 H+ 梯度。将相同的制剂掺入平面脂质双层后，Ca2+ 会引发与 MMC/PTP 相匹配的电流。电流是完全可逆的，被 F-ATP 合酶 OSCP 亚基配体苯二氮䓬 423 稳定，该配体能激活 MMC/PTP，并且被 Mg 和腺嘌呤核苷酸抑制，而腺嘌呤核苷酸也能抑制 PTP。通道活性对腺嘌呤核苷酸转运蛋白（ANT）和电压依赖性阴离子通道（VDAC）的抑制剂不敏感。天然凝胶纯化的寡聚体和二聚体，但不是单体，产生了通道活性。这些发现解决了 MMC/PTP 长期存在的谜团，并表明 Ca2+ 可以将能量守恒的 F-ATP 合酶转化为能量耗散装置。
