Disruption of cytochrome c heme coordination is responsible for mitochondrial injury during ischemia.
Disruption of cytochrome c heme coordination is responsible for mitochondrial injury during ischemia.
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DOI：
10.1016/j.bbabio.2015.06.006
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发表时间：
2015-10
期刊：
影响因子：
--
通讯作者：
Szeto HH
中科院分区：
文献类型：
--
作者：
Birk AV;Chao WM;Liu S;Soong Y;Szeto HH
It was recently suggested that electron flow into cyt c, coupled with ROS generation, oxidizes cyt c Met80 to Met80 sulfoxide (Met-O) in isolated hearts after ischemia-reperfusion, and converts cyt c to a peroxidase. We hypothesize that ischemia disrupts Met80-Fe ligation of cyt c, forming pentacoordinated heme Fe2+, which inhibits electron transport (ET) and promotes oxygenase activity. SS-20 (Phe-D-Arg-Phe-Lys-NH2) was used to demonstrate the role of Met80-Fe ligation in ischemia. Mitochondria were isolated from ischemic rat kidneys to determine sites of respiratory inhibition. Mitochondrial cyt c and cyt c Met-O were quantified by western blot, and cristae architecture was examined by electron microscopy. Biochemical and structural studies showed that SS-20 selectively targets cardiolipin (CL) and protects Met80-Fe ligation in cyt c. Ischemic mitochondria showed 17-fold increase in Met-O cyt c, and dramatic cristaeolysis. Loss of cyt c was associated with proteolytic degradation of OPA1. Ischemia significantly inhibited ET initiated by direct reduction of cyt c and coupled respiration. All changes were prevented by SS-20. Our results show that ischemia disrupts the Met80-Fe ligation of cyt c resulting in formation of a globin-like pentacoordinated heme Fe2+ that inhibits ET, and converts cyt c into an oxygenase to cause CL peroxidation and proteolytic degradation of OPA1, resulting in cyt c release. Cyt c heme structure represents a novel target for minimizing ischemic injury. SS-20, which we show to selectively target CL and protect the Met80-Fe ligation, minimizes ischemic injury and promotes ATP recovery.
