Vold B S, Green C J, Narasimhan N, Strem M, Hansen J N
Department of Molecular Biology, SRI International, Menlo Park, California 94025.
J Biol Chem. 1988 Oct 5;263(28):14485-90.
This is part of a series of two papers on gene regulation in Bacillus subtilis rRNA-tRNA operons that contain large clusters of tRNA genes. The preceding paper (Vold, B.S., Okamoto, K., Murphy, B.J., and Green, C.J. (1988) J. Biol. Chem. 263, 14480-14484) investigates the rrnB operon containing 21 tRNA genes, and this paper investigates a B. subtilis rRNA-tRNA operon containing 16 tRNA genes and a minor 5 S rRNA. Hybridization studies suggest this minor 5 S rRNA occurs as a single copy in the B. subtilis 168 genome. S1 nuclease mapping indicates that this minor 5 S rRNA gene has its own promoter. No promoters have been found immediately 5' to any of the major 5 S rRNA species in B. subtilis rRNA operons. S1 mapping of the spacer region between the 23 S and minor 5 S rRNA revealed that the maturation of the 23 S rRNA in this operon may arise from an unusual processing mechanism. S1 nuclease mapping experiments suggest the existence of a promoter element immediately upstream of the last gene, for tRNA(Leu CAA), in the operon. A precursor leucine tRNA resulting from transcription of this last tRNA gene was observed in Northern hybridizations, and the amounts of this precursor increased during sporulation. A single terminator-like element is located just upstream of this last tRNA gene; however, S1 nuclease mapping experiments suggest that some read-through transcription occurs. Thus, all 16 tRNA genes are under control of the upstream 16 S rRNA promoters and the minor 5 S rRNA promoter. However, the last tRNA gene is primarily under the control of its own unique promoter.
这是关于枯草芽孢杆菌rRNA - tRNA操纵子中基因调控的两篇系列论文中的一部分，这些操纵子包含大量tRNA基因簇。前一篇论文（Vold, B.S., Okamoto, K., Murphy, B.J., and Green, C.J. (1988) J. Biol. Chem. 263, 14480 - 14484）研究了包含21个tRNA基因的rrnB操纵子，而本文研究的是一个含有16个tRNA基因和一个小的5S rRNA的枯草芽孢杆菌rRNA - tRNA操纵子。杂交研究表明，这个小的5S rRNA在枯草芽孢杆菌168基因组中以单拷贝形式存在。S1核酸酶图谱分析表明，这个小的5S rRNA基因有其自身的启动子。在枯草芽孢杆菌rRNA操纵子中，尚未在任何主要的5S rRNA种类的紧邻5'端发现启动子。对23S和小的5S rRNA之间间隔区的S1图谱分析表明，该操纵子中23S rRNA的成熟可能源于一种不寻常的加工机制。S1核酸酶图谱分析实验表明，在该操纵子中最后一个基因tRNA(Leu CAA)的紧邻上游存在一个启动子元件。在Northern杂交中观察到由这个最后一个tRNA基因转录产生的前体亮氨酸tRNA，并且在芽孢形成过程中该前体的量增加。在这个最后一个tRNA基因的紧邻上游仅定位有一个类似终止子的元件；然而，S1核酸酶图谱分析实验表明存在一些通读转录。因此，所有16个tRNA基因受上游16S rRNA启动子和小的5S rRNA启动子的控制。然而，最后一个tRNA基因主要受其自身独特启动子的控制。
