Arabidopsis Tic40 expression in tobacco chloroplasts results in massive proliferation of the inner envelope membrane and upregulation of associated proteins.
Arabidopsis Tic40 expression in tobacco chloroplasts results in massive proliferation of the inner envelope membrane and upregulation of associated proteins.
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拟南芥 Tic40 在烟草叶绿体中的表达导致内膜的大量增殖和相关蛋白的上调。
DOI：
10.1105/tpc.108.063172
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
Daniell,Henry
中科院分区：
文献类型：
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作者：
Singh,NameirakpamDolendro;Li,Ming;Lee,Sueng-Bum;Schnell,Danny;Daniell,Henry
叶绿体内被膜在植物体内的脂类合成、代谢物运输和细胞信号转导中起着重要作用。我们已经针对一个模型的细胞核编码的IM蛋白从拟南芥，前Tic40-His，通过重新定位其表达从细胞核到叶绿体基因组。Pre-Tic40-His被正确定位、处理和插入。它获得了正确的拓扑结构，并被折叠和组装成TIC复合物，其中它占叶绿体总蛋白的15%。这些结果证实了蛋白质靶向IM的新途径的存在。Tic40-His过表达导致IM的大量增殖（在电子显微镜下多达19层），而对植物生长或繁殖没有显著影响。与IM增殖一致，其他内源性IM蛋白的表达水平（IEP37，PPT，Tic110）显著上调（10倍），但外被膜（Toc159），基质膜（Toc159），（hsp93，cpn60）或类囊体（LHCP，OE23）蛋白未增加，这表明叶绿体和核基因组之间的逆向信号转导增加脂质和蛋白质组分以适应Tic40积累的增加。这项研究打开了大门，了解细胞器内的膜生物发生的调节和利用转基因叶绿体作为生物反应器的膜蛋白的超积累生物技术应用。
The chloroplast inner envelope membrane (IM) plays essential roles in lipid synthesis, metabolite transport, and cellular signaling in plants. We have targeted a model nucleus-encoded IM protein fromArabidopsis thaliana, pre-Tic40-His, by relocating its expression from the nucleus to the chloroplast genome. Pre-Tic40-His was properly targeted, processed, and inserted. It attained correct topology and was folded and assembled into a TIC complex, where it accounted for up to 15% of the total chloroplast protein. These results confirm the existence of a novel pathway for protein targeting to the IM. Tic40-His overexpression resulted in a massive proliferation of the IM (up to 19 layers in electron micrographs) without significant effects on plant growth or reproduction. Consistent with IM proliferation, the expression levels of other endogenous IM proteins (IEP37, PPT, Tic110) were significantly (10-fold) upregulated but those of outer envelope membrane (Toc159), stromal (hsp93, cpn60), or thylakoid (LHCP, OE23) proteins were not increased, suggesting retrograde signal transduction between chloroplast and nuclear genomes to increase lipid and protein components for accommodation of increased accumulation of Tic40. This study opens the door for understanding the regulation of membrane biogenesis within the organelle and the utilization of transgenic chloroplasts as bioreactors for hyperaccumulation of membrane proteins for biotechnological applications.