Mitochondria fulfil essential functions in respiration and metabolism as well as regulating stress responses and apoptosis. Most native mitochondrial proteins are encoded by nuclear genes and are imported into mitochondria via one of several receptors that recognize N-terminal signal peptides. The targeting of recombinant proteins to mitochondria therefore requires the presence of an appropriate N-terminal peptide, but little is known about mitochondrial import in monocotyledonous plants such as rice (Oryza sativa). To gain insight into this phenomenon, we targeted nuclear-encoded enhanced green fluorescent protein (eGFP) to rice mitochondria using six mitochondrial pre-sequences with diverse phylogenetic origins, and investigated their effectiveness by immunoblot analysis as well as confocal and electron microscopy. We found that the ATPA and COX4 (Saccharomyces cerevisiae), SU9 (Neurospora crassa), pFA (Arabidopsis thaliana) and OsSCSb (Oryza sativa) peptides successfully directed most of the eGFP to the mitochondria, whereas the MTS2 peptide (Nicotiana plumbaginifolia) showed little or no evidence of targeting ability even though it is a native plant sequence. Our data therefore indicate that the presence of particular recognition motifs may be required for mitochondrial targeting, whereas the phylogenetic origin of the pre-sequences probably does not play a key role in the success of mitochondrial targeting in dedifferentiated rice callus and plants.

中文翻译：

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识别基序而不是系统发育起源影响靶向肽将核编码重组蛋白导入水稻线粒体的能力。


线粒体在呼吸和新陈代谢以及调节应激反应和细胞凋亡中发挥重要功能。大多数天然线粒体蛋白由核基因编码，并通过识别 N 端信号肽的几种受体之一导入线粒体。因此，将重组蛋白靶向线粒体需要存在适当的 N 末端肽，但人们对稻等单子叶植物中线粒体的输入知之甚少。为了深入了解这一现象，我们使用具有不同系统发育起源的六个线粒体前序列将核编码的增强型绿色荧光蛋白（eGFP）靶向水稻线粒体，并通过免疫印迹分析以及共聚焦和电子显微镜研究其有效性。我们发现 ATPA 和 COX4（酿酒酵母）、SU9（粗糙脉孢菌）、pFA（拟南芥）和 OsSCSb（稻）肽成功地将大部分 eGFP 引导至线粒体，而 MTS2 肽（烟草）几乎没有表现出 eGFP 定向到线粒体。或没有证据表明靶向能力，即使它是天然植物序列。因此，我们的数据表明，线粒体靶向可能需要特定识别基序的存在，而前序列的系统发育起源可能在去分化水稻愈伤组织和植物中线粒体靶向的成功中不起关键作用。