Guo Q, Lambowitz A M
Department of Molecular Genetics, Ohio State University, Columbus 43210.
Genes Dev. 1992 Aug;6(8):1357-72. doi: 10.1101/gad.6.8.1357.
The Neurospora CYT-18 protein, the mitochondrial tyrosyl-tRNA synthetase, functions in splicing group I introns in mitochondria. Here, we show that CYT-18 binds strongly to diverse group I introns that have minimal sequence homology and recognizes highly conserved structural features of the catalytic core of these introns. Inhibition experiments indicate that the intron RNA and tRNA(Tyr) compete for the same or overlapping binding sites in the CYT-18 protein. Considered together with functional analysis, our results indicate that the CYT-18 protein promotes splicing by binding to the intron core and stabilizing it in a conformation required for catalytic activity. Furthermore, the specific binding of the synthetase suggests that the group I intron catalytic core has structural similarities to tRNAs, which could reflect either convergent evolution or an evolutionary relationship between group I introns and tRNAs.
粗糙脉孢菌的CYT - 18蛋白即线粒体酪氨酸 - tRNA合成酶，在线粒体中参与I组内含子的剪接。在此，我们表明CYT - 18能强烈结合多种序列同源性极低的I组内含子，并识别这些内含子催化核心的高度保守结构特征。抑制实验表明，内含子RNA和tRNA(Tyr)在CYT - 18蛋白中竞争相同或重叠的结合位点。结合功能分析，我们的结果表明CYT - 18蛋白通过结合内含子核心并将其稳定在催化活性所需的构象来促进剪接。此外，合成酶的特异性结合表明I组内含子催化核心与tRNA具有结构相似性，这可能反映了趋同进化或I组内含子与tRNA之间的进化关系。
