Hedtke B, Börner T, Weihe A
Institut für Biologie, Abteilung Genetik, Humboldt-Universität zu Berlin, Germany.
EMBO Rep. 2000 Nov;1(5):435-40. doi: 10.1093/embo-reports/kvd086.
The land plant Arabidopsis thaliana contains three closely related nuclear genes encoding phage-type RNA polymerases (RpoT;1, RpoT;2 and RpoT;3). The gene products of RpoT;1 and RpoT;3 have previously been shown to be imported into mitochondria and chloroplasts, respectively. Here we show that the transit peptide of RpoT;2 possesses dual targeting properties. Transient expression assays in tobacco protoplasts as well as stable transformation of Arabidopsis plants demonstrate efficient targeting of fusion peptides consisting of the N-terminus of RpoT;2 joined to green fluorescent protein to both organelles. Thus, RpoT;2 might be the first RNA polymerase shown to transcribe genes in two different genomes. RNA polymerase activity of recombinant RpoT;2 is uneffected by the inhibitor tagetin, qualifying the gene product of RpoT;2 as a phage-type polymerase.
陆地植物拟南芥含有三个密切相关的核基因，它们编码噬菌体类型的RNA聚合酶（RpoT;1、RpoT;2和RpoT;3）。先前已证明RpoT;1和RpoT;3的基因产物分别被导入线粒体和叶绿体。在这里，我们表明RpoT;2的转运肽具有双重靶向特性。烟草原生质体中的瞬时表达分析以及拟南芥植物的稳定转化表明，由RpoT;2的N端与绿色荧光蛋白连接而成的融合肽能够有效地靶向这两种细胞器。因此，RpoT;2可能是首个被证明能在两个不同基因组中转录基因的RNA聚合酶。重组RpoT;2的RNA聚合酶活性不受抑制剂塔格汀的影响，这表明RpoT;2的基因产物是一种噬菌体类型的聚合酶。
