du Jardin P, Portetelle D, Harvengt L, Dumont M, Wathelet B
Unité de Génétique et d'Amélioration des Plantes, Faculté des Sciences Agronomiques, Gemboux, Belgium.
Curr Genet. 1994 Feb;25(2):158-63. doi: 10.1007/BF00309542.
The trnK gene has been identified on a cloned plastid DNA fragment of potato (Solanum tuberosum cv Désirée). This gene codes for a tRNA-Lys and is interrupted by a 2.5-kb intron belonging to the group II organellar introns. In addition, this intervening sequence contains a long open reading frame potentially coding for a 509 amino-acid polypeptide (ORF509) related to mitochondrial intron-encoded maturases from fungi. The translational capacity of the trnK intron was first demonstrated in vitro in a prokaryotic DNA-directed expression system. In order to examine the expression of the intron in the potato plant, a synthetic peptide corresponding to the last nine amino acids of the predicted ORF509 product was used to raise antibodies. Western-blot experiments on chloroplast protein extracts, using a sensitive chemiluminescent detection system, identified polypeptides similar to in-vitro products. These results suggest that the trnK intron is expressed at the protein level in the plant. This is the first report of the in-vivo expression of an intron-encoded polypeptide in higher plant plastids.
trnK基因已在马铃薯（Solanum tuberosum cv Désirée）的一个克隆质体DNA片段上被鉴定出来。该基因编码一种赖氨酸转运RNA（tRNA-Lys），并被一个属于II类细胞器内含子的2.5 kb内含子打断。此外，这个间隔序列包含一个长开放阅读框，可能编码一个与真菌线粒体内含子编码的成熟酶相关的509个氨基酸的多肽（ORF509）。trnK内含子的翻译能力首先在原核DNA指导的表达系统中进行了体外验证。为了检测该内含子在马铃薯植株中的表达，使用了一种与预测的ORF509产物的最后九个氨基酸相对应的合成肽来制备抗体。利用灵敏的化学发光检测系统对叶绿体蛋白提取物进行的蛋白质印迹实验，鉴定出了与体外产物相似的多肽。这些结果表明，trnK内含子在植物中以蛋白质水平表达。这是高等植物质体中内含子编码多肽体内表达的首次报道。
