Dombrowski S, Brennicke A, Binder S
Allgemeine Botanik, Universität Ulm, Germany.
EMBO J. 1997 Aug 15;16(16):5069-76. doi: 10.1093/emboj/16.16.5069.
A number of mRNAs in plant mitochondria contain inverted repeats at their 3'-termini. These have been discussed as potential transcription terminators or, alternatively, as post-transcriptional processing and stability signals of longer precursor RNAs. In vitro transcription in a pea mitochondrial lysate now shows that transcription proceeds almost unimpeded through these inverted repeat structures. To investigate their potential function in mRNA processing, we developed an in vitro processing system from pea mitochondria. This in vitro system correctly processes synthetic precursor mRNAs containing the pea atp9 double stem-loop structure, yielding the same 3'-termini observed in vivo. Analysis of the in vitro-generated products and of the processivity of the reaction suggests exonucleolytic degradation up to the stem-loop. The inverted repeat structures found at the 3'-termini of mRNAs in plant mitochondria are thus recognized as processing and most likely also stabilizing signals in transcript maturation, but do not terminate transcription.
植物线粒体中的许多mRNA在其3'末端含有反向重复序列。这些反向重复序列被认为是潜在的转录终止子，或者是较长前体RNA的转录后加工和稳定性信号。现在，豌豆线粒体裂解物中的体外转录表明，转录几乎不受阻碍地通过这些反向重复结构进行。为了研究它们在mRNA加工中的潜在功能，我们开发了一种来自豌豆线粒体的体外加工系统。该体外系统能够正确加工含有豌豆atp9双茎环结构的合成前体mRNA，产生与体内观察到的相同的3'末端。对体外生成产物和反应持续性的分析表明，核酸外切酶降解一直持续到茎环结构。因此，植物线粒体mRNA 3'末端的反向重复结构被认为是转录成熟过程中的加工信号，很可能也是稳定信号，但不会终止转录。
