Gourse R L, de Boer H A, Nomura M
Cell. 1986 Jan 17;44(1):197-205. doi: 10.1016/0092-8674(86)90498-8.
We have examined the DNA regions required for rRNA synthesis in E. coli using promoter-lacZ and lambda PL-rrnB operon fusions. Sequences between -51 and -20 with respect to the P1 promoter transcription initiation site contain the critical information for growth rate dependent control. The region essential for growth rate regulation is the same as that necessary for feedback inhibition. A separate upstream region, between -51 and -88, increases rRNA transcription at least 15-fold and appears to have an abnormal conformation. The box A sequence downstream of promoter P2, but not DNA between P2 and box A, is required for efficient rRNA chain elongation. These results indicate that neither upstream activation nor antitermination determines growth rate dependence. Rather, growth rate regulation takes place at the target site for the negative feedback system, the P1 promoter itself. We propose that negative feedback regulation is responsible for the growth rate dependence of rRNA synthesis in E. coli.
我们利用启动子 - lacZ和λPL - rrnB操纵子融合技术，研究了大肠杆菌中rRNA合成所需的DNA区域。相对于P1启动子转录起始位点，-51至-20之间的序列包含了生长速率依赖性调控的关键信息。生长速率调节所必需的区域与反馈抑制所必需的区域相同。一个单独的上游区域，在-51至-88之间，可使rRNA转录增加至少15倍，并且似乎具有异常构象。启动子P2下游的A框序列，但不是P2和A框之间的DNA，是rRNA链有效延伸所必需的。这些结果表明，上游激活和抗终止都不能决定生长速率依赖性。相反，生长速率调节发生在负反馈系统的靶位点，即P1启动子本身。我们提出，负反馈调节是大肠杆菌中rRNA合成生长速率依赖性的原因。
