DEPLETION OF FUNCTIONAL RIBOSOMAL-RNA OPERONS IN ESCHERICHIA-COLI CAUSES INCREASED EXPRESSION OF THE REMAINING INTACT COPIES
DEPLETION OF FUNCTIONAL RIBOSOMAL-RNA OPERONS IN ESCHERICHIA-COLI CAUSES INCREASED EXPRESSION OF THE REMAINING INTACT COPIES
复制标题
DOI：
10.1002/j.1460-2075.1993.tb06115.x
复制
发表时间：
1993-11-01
期刊：
影响因子：
11.4
通讯作者：
SQUIRES, CL
中科院分区：
文献类型：
--
作者：
CONDON, C;FRENCH, S;SQUIRES, CL
核糖体RNA的合成是一个复杂且高度受调控的过程。为了研究这一过程，我们使用删除插入顺序破坏大肠杆菌基因组上的7个rRNA（rrn）操纵子中的一个到四个。四个rrn操纵子的失活导致氯霉素乙酰转移酶报告基因的表达增加了2.3倍，该报告基因融合到rrnA的串联启动子中，并且在rrnC的末端处的Trp tRNA基因的表达也有类似的增加。这反映了剩余操纵子的增强表达以补偿仅有三个完整拷贝。升高的表达是由转录起始和RNA聚合酶延伸率的增加引起的，特别是在rrn操纵子上，并且在没有ppGpp细胞内浓度变化的情况下发生，这表明ppGpp不参与这种现象的调节。我们讨论了这些结果与核糖体反馈抑制模型所描述的野村和同事。
The synthesis of ribosomal RNA is a complex and highly regulated process. To study this process, we have used deletion-insertions to disrupt sequentially from one to four of the seven rRNA (rrn) operons on the Escherichia coli genome. Inactivation of four rrn operons caused a 2.3-fold increase in the expression of a chloramphenicol acetyl transferase reporter gene fused to the tandem promoters of rrnA and a similar increase in the expression of the trp tRNA gene at the end of rrnC. This reflected enhanced expression of the remaining operons to compensate for having only three intact copies. The elevated expression was caused by an increase in both transcription initiation and RNA polymerase elongation rates specifically on rrn operons and occurred in the absence of changes in the intracellular concentration of ppGpp, suggesting that ppGpp is not involved in the regulation of this phenomenon. We discuss these results in relation to the ribosome feedback inhibition model described by Nomura and coworkers.