Hofmann T J, Min J, Zassenhaus H P
Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, NJ 08544.
Yeast. 1993 Dec;9(12):1319-30. doi: 10.1002/yea.320091205.
Mitochondrial mRNAs in yeast arise by processing of polygenic primary transcripts at a conserved dodecamer sequence (5'-AAUAAPyAUUCUU-3'). Previous results indicated that processing at dodecamer sites interrupted the sequence implying that it functioned primarily as a signal for 3' end formation of mRNAs. We have determined the precise cleavage site for RNAs processed at the dodecamer sequences associated with the oli1 gene and the omega intron of the 21S rRNA gene. In both cases cleavage occurred two bases downstream of the site. Hydrolysis left the PO4 group attached to the 3' terminus of the cleavage products. These results demonstrate for the first time that mature mitochondrial mRNAs terminate with an intact dodecamer sequence. In light of the recent identification of a protein complex within mitochondria that binds to RNAs terminating with an intact dodecamer sequence, these results support the idea that the dodecamer sequence functions not only within pre-mRNAs as a processing site, but within mature mRNAs as well, possibly for the stabilization and/or translation.
酵母中的线粒体mRNA是通过在保守的十二聚体序列（5'-AAUAAPyAUUCUU-3'）处对多基因初级转录本进行加工而产生的。先前的结果表明，在十二聚体位点的加工会中断序列，这意味着它主要作为mRNA 3'末端形成的信号发挥作用。我们已经确定了与oli1基因和21S rRNA基因的ω内含子相关的十二聚体序列处加工的RNA的精确切割位点。在这两种情况下，切割都发生在该位点下游的两个碱基处。水解使磷酸基团连接在切割产物的3'末端。这些结果首次证明成熟的线粒体mRNA以完整的十二聚体序列终止。鉴于最近在线粒体内鉴定出一种与以完整十二聚体序列终止的RNA结合的蛋白质复合物，这些结果支持这样一种观点，即十二聚体序列不仅在mRNA前体中作为加工位点发挥作用，而且在成熟mRNA中也发挥作用，可能用于稳定和/或翻译。
