Substitution of the gene for chloroplast RPS16 was assisted by generation of a dual targeting signal
Substitution of the gene for chloroplast RPS16 was assisted by generation of a dual targeting signal
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DOI：
10.1093/molbev/msn102
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发表时间：
2008-08-01
影响因子：
10.7
通讯作者：
Kadowaki, Koh-ichi
中科院分区：
文献类型：
--
作者：
Ueda, Minoru;Nishikawa, Tomotaro;Kadowaki, Koh-ichi
内共生发生后，植物细胞器（线粒体和叶绿体）基因组中大量基因丢失。即使在这种主要基因丢失之后，细胞器基因组仍然丢失了它们自己的基因，即使是那些必需的基因，通过基因转移到细胞核和不同细胞器起源的基因替换或从头基因。基因转移和替换事件是真核细胞进化中的重要过程。基因丢失是高等植物线粒体和叶绿体中的一个持续过程。核糖体蛋白S16（rps 16）基因在大多数高等植物的叶绿体基因组中编码，但在蒺藜苜蓿（Medicago truncatula）和白杨（Populus alba）中不编码。在这里，我们表明，这两个物种已经补偿了损失的rps 16从叶绿体基因组具有线粒体rps 16，可以靶向叶绿体以及线粒体。此外，在拟南芥，番茄，水稻，其叶绿体基因组编码的rps 16，我们表明，线粒体rps 16的产品具有双重靶向能力。这些结果表明，RPS 16对线粒体和叶绿体的双重靶向在单子叶植物和双子叶植物分化之前出现（140-150 MYA）。在高等植物中叶绿体rps 16的基因替换为核编码的rps 16是关于正在进行的基因替换的双靶向的第一个报告，并提供了证据，在形成这种异质性细胞器的中间阶段。
Organelle (mitochondria and chloroplasts in plants) genomes lost a large number of genes after endosymbiosis occurred. Even after this major gene loss, organelle genomes still lose their own genes, even those that are essential, via gene transfer to the nucleus and gene substitution of either different organelle origin or de novo genes. Gene transfer and substitution events are important processes in the evolution of the eukaryotic cell. Gene loss is an ongoing process in the mitochondria and chloroplasts of higher plants. The gene for ribosomal protein S16 (rps16) is encoded in the chloroplast genome of most higher plants but not in Medicago truncatula and Populus alba. Here, we show that these 2 species have compensated for loss of the rps16 from the chloroplast genome by having a mitochondrial rps16 that can target the chloroplasts as well as mitochondria. Furthermore, in Arabidopsis thaliana, Lycopersicon esculentum, and Oryza sativa, whose chloroplast genomes encode the rps16, we show that the product of the mitochondrial rps16 has dual targeting ability. These results suggest that the dual targeting of RPS16 to the mitochondria and chloroplasts emerged before the divergence of monocots and dicots (140-150 MYA). The gene substitution of the chloroplast rps16 by the nuclear-encoded rps16 in higher plants is the first report about ongoing gene substitution by dual targeting and provides evidence for an intermediate stage in the formation of this heterogeneous organelle.