Brink S, Flügge U I, Chaumont F, Boutry M, Emmermann M, Schmitz U, Becker K, Pfanner N
Julius-von Sachs-Institut für Biowissenschaften, Universität Würzburg, Federal Republic of Germany.
J Biol Chem. 1994 Jun 10;269(23):16478-85.
The amino-terminal transit sequences of two preproteins destined for the chloroplast inner envelope membrane show similarities to mitochondrial presequences in the prevalence of positive charges and the potential formation of an amphipathic alpha-helix. We studied if these preproteins could be imported into mitochondria and found a low, yet significant import into isolated plant mitochondria. The plant mitochondria were previously shown not to import precursors of chloroplast stromal or thylakoidal proteins. To analyze the specificity of import into mitochondria we used the established import systems of fungal mitochondria. The envelope preproteins were efficiently imported into Saccharomyces cerevisiae or Neurospora crassa mitochondria. Their import showed the characteristics of specific mitochondrial protein uptake, including a requirement for the main receptor MOM19 (mitochondrial outer membrane protein of 19 kDa) and a membrane potential across the inner membrane, and depended on the presence of the chloroplast transit sequence. We conclude that some chloroplast transit sequences contain sufficient information for specific interaction with mitochondrial import receptors (at least from fungal sources).
两种定位于叶绿体内膜的前体蛋白的氨基末端转运序列，在正电荷的分布以及两亲性α螺旋的潜在形成方面，与线粒体前导序列相似。我们研究了这些前体蛋白是否能够被导入线粒体，结果发现它们能够以较低但显著的效率被导入分离的植物线粒体中。此前的研究表明，这些植物线粒体不能导入叶绿体基质或类囊体蛋白的前体。为了分析导入线粒体的特异性，我们使用了已建立的真菌线粒体导入系统。这些内膜前体蛋白能够高效地被导入酿酒酵母或粗糙脉孢菌的线粒体中。它们的导入表现出特异性线粒体蛋白摄取的特征，包括对主要受体MOM19（19 kDa的线粒体外膜蛋白）的需求以及内膜两侧的膜电位，并且依赖于叶绿体转运序列的存在。我们得出结论，一些叶绿体转运序列包含与线粒体导入受体（至少来自真菌来源）进行特异性相互作用的足够信息。
