A mitochondrial signal peptide from Neurospora crassa increases the permeability of isolated rat liver mitochondria.
A mitochondrial signal peptide from Neurospora crassa increases the permeability of isolated rat liver mitochondria.
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来自粗糙脉孢菌的线粒体信号肽可增加离体大鼠肝线粒体的通透性。
DOI：
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发表时间：
1996
影响因子：
3.9
通讯作者：
K. Kinnally
中科院分区：
文献类型：
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作者：
P. M. Sokolove;K. Kinnally;K. Kinnally
含有Ca 2+的线粒体可以通过多种触发剂和条件诱导进行渗透性转变（PT）;内膜变得对小溶质非选择性渗透。Mastoparan，一种来自黄蜂毒液的两亲性肽，最近报道诱导这种转变（Pfeiffer et al.，1995，J.Biol.Chem.270，4923）。我们已经研究了第二个两亲性肽，细胞色素氧化酶亚基IV从粗糙脉孢菌（pCoxIV，氨基酸3-22），其目标亚基IV的线粒体位置的信号序列，对离体大鼠肝线粒体的渗透性的影响。通过线粒体肿胀观察渗透性增加，结果如下。(1)pCoxIV（5-100 μ M）诱导浓度依赖性线粒体肿胀。来自电压依赖性阴离子选择性通道的N-和C-末端的对照肽没有这种作用。(2)肿胀需要线粒体通电;它可以通过解偶联剂羰腈对-（三氟甲氧基）苯腙消除或停止。(3)增加KCl浓度可减缓肽诱导的肿胀。(4)无机磷酸盐（<1 mM）可增强溶胀。(5)三氟拉嗪（50 μ M），普萘洛尔（0.5 mM）和地布卡因（0.5 mM）是肽诱导的肿胀的有效抑制剂，而经典PT的其他抑制剂（环孢菌素A，EGTA和ADP）仅部分抑制。(6)pCoxIV打开了一个孔，而不是破坏线粒体膜结构，但50%的肽诱导的肿胀抑制需要的分子量基本上大于所需的抑制钙离子诱导的PT到相同程度的聚乙二醇。总之，pCoxIV在分离的线粒体中打开孔。膜电位上的孔开放和抑制肽诱导的渗透性增加的依赖性，通过增加盐浓度表明，这种影响的信号肽是与它的相互作用与线粒体在蛋白质进口。然而，肽诱导的孔似乎与经典的渗透性转变孔和mastoparan诱导的渗透性增加不同。
Mitochondria that contain Ca2+ can be induced by a variety of triggering agents and conditions to undergo a permeability transition (PT); the inner membrane becomes nonselectively permeable to small solutes. Mastoparan, an amphipathic peptide from wasp venom, has recently been reported to induce this transition (Pfeiffer et al., 1995, J. Biol. Chem. 270,4923). We have examined the effect on the permeability of isolated rat liver mitochondria of a second amphipathic peptide, the signal sequence of cytochrome oxidase subunit IV from Neurospora crassa (pCoxIV, amino acids 3-22), which targets subunit IV to its mitochondrial location. Permeability increases were visualized via mitochondrial swelling with the following results. (1) pCoxIV (5-100 microM) induced concentration-dependent mitochondrial swelling. Control peptides from the N- and C-termini of the voltage-dependent anion-selective channel had no such effect. (2) Swelling required mitochondrial energization; it was eliminated or halted by the uncoupler carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone. (3) Peptide-induced swelling was slowed by increasing concentrations of KCl. (4) Swelling was enhanced by inorganic phosphate (<1 mM). (5) Trifluoperazine (50 microM), propranolol (0.5 mM), and dibucaine (0.5 mM) were potent inhibitors of peptide-induced swelling, whereas other inhibitors of the classical PT (cyclosporin A, EGTA, and ADP) inhibited only partially. (6) pCoxIV opened a pore rather than disrupting mitochondrial membrane structure, but 50% inhibition of peptide-induced swelling required polyethylene glycol of molecular weight substantially larger than that needed to inhibit the Ca2+-induced PT to the same extent. In summary, pCoxIV opens a pore in isolated mitochondria. The dependence of pore opening on membrane potential and the inhibition of the peptide-induced permeability increase by increasing salt concentration suggest that this effect of the signal peptide is related to its interactions with mitochondria during protein import. The peptide-induced pore appears, however, to be distinct from both the classical permeability transition pore and the mastoparan-induced permeability increase.