Vallette F M, Juin P, Pelleschi M, Henry J P
Centre National de la Recherche Scientifique, Unité de Recherche Associée 1112, Paris, France.
J Biol Chem. 1994 May 6;269(18):13367-74.
The interaction of several basic peptides with yeast mitochondria has been analyzed. The peptides were selected for their ability to block a cationic channel of the outer membrane, the peptide-sensitive channel. These peptides possess common characteristics, such as a net positive charge superior to 2 and the capacity to form amphiphilic structures. They can be divided into two classes as follows: peptides of class I derived from mitochondrial signal peptides, such as the presequence of cytochrome c oxidase subunit IV, e.g. pCyt OX IV (1-12) Y; and peptides of class II unrelated to the mitochondria, such as dynorphin B (1-13). Class I peptides inhibited the translocation of a chimeric protein, cytochrome b2-DHFR, into the mitochondrial matrix, whereas peptides of class II failed to inhibit this import. Experiments with iodinated pCyt OX IV (1-12) Y and dynorphin B (1-13) showed, however, that both types of peptides were imported into yeast mitochondria in vitro and subsequently degraded. At 30 degrees C, two import mechanisms could be distinguished; the mitochondrial presequences (class I) were translocated into the matrix in a temperature- and potential-sensitive manner, probably along the general import pathway, while class II dynorphin B (1-13) was imported into the intermembrane space by a process that was neither temperature- nor potential-sensitive. At 0 degree C, both peptides were imported in a class II manner. The class II characteristics suggested the existence of a direct pathway into the intermembrane space, which may be associated with the peptide-sensitive channel. This hypothesis is substantiated by the competition for the import into the mitochondria between peptides of the two classes. The import of pCyt OX (1-12) Y was inhibited at 30 degrees C only by peptides of class I, IV whereas, at 0 degree C, this import was also inhibited by peptides of class II. Import of peptides of the latter class was inhibited by peptides of the two classes both at 0 degree C and 30 degrees C.
分析了几种碱性肽与酵母线粒体的相互作用。这些肽因其阻断外膜阳离子通道（肽敏感通道）的能力而被挑选出来。这些肽具有共同特征，如净正电荷大于2以及形成两亲结构的能力。它们可分为以下两类：I类肽源自线粒体信号肽，如细胞色素c氧化酶亚基IV的前导序列，例如pCyt OX IV (1 - 12) Y；II类肽与线粒体无关，如强啡肽B (1 - 13)。I类肽抑制嵌合蛋白细胞色素b2 - DHFR向线粒体基质的转运，而II类肽未能抑制这种导入。然而，用碘化的pCyt OX IV (1 - 12) Y和强啡肽B (1 - 13)进行的实验表明，这两种类型的肽在体外都能导入酵母线粒体并随后被降解。在30℃时，可以区分出两种导入机制；线粒体前导序列（I类）以温度和电位敏感的方式转运到基质中，可能是沿着一般导入途径，而II类强啡肽B (1 - 13)通过一个既不依赖温度也不依赖电位的过程导入到膜间隙。在0℃时，两种肽都以II类方式导入。II类特征表明存在一条直接进入膜间隙的途径，这可能与肽敏感通道有关。两类肽之间对导入线粒体的竞争证实了这一假设。pCyt OX (1 - 12) Y的导入在30℃时仅被I类肽抑制，而在0℃时，这种导入也被II类肽抑制。后一类肽的导入在0℃和30℃时都被两类肽抑制。
