Aviv M, Giladi H, Oppenheim A B, Glaser G
Department of Cellular Biochemistry, Hebrew University--Hadassah Medical School, Jerusalem, Israel.
FEMS Microbiol Lett. 1996 Jun 15;140(1):71-6. doi: 10.1111/j.1574-6968.1996.tb08317.x.
Most bacterial RNA consists of stable RNA which is composed of rRNA and tRNA. We have followed by primer extension analysis the level of ribosomal RNA synthesis along the growth phases of a cell culture. A sharp drop in rRNA synthesis was observed upon the transition from the exponential to the stationary phase of growth. Our results demonstrate that an effective shut-off of rRNA synthesis occurs also in the absence of ppGpp. Mutations in the host factors Fis and H-NS, which are known to regulate rrn P1 promoters, did not affect the shut-off process of ribosomal RNA promoters. We also tested the effect of RpoS, the sigma factor known to induce a number of genes in the stationary phase. It was shown that the host factors Fis, H-NS and RpoS do not play a major role in the regulation of the shut-off process of rRNA synthesis. The results presented demonstrate that the rate of rRNA synthesis provides a sensitive measure of the growth phase of the bacterial culture.
大多数细菌RNA由稳定RNA组成，而稳定RNA又由核糖体RNA（rRNA）和转运RNA（tRNA）构成。我们通过引物延伸分析跟踪了细胞培养物在不同生长阶段核糖体RNA的合成水平。在从指数生长期过渡到稳定期时，观察到rRNA合成急剧下降。我们的结果表明，即使在没有鸟苷四磷酸（ppGpp）的情况下，rRNA合成也会有效关闭。已知宿主因子Fis和H-NS可调节rrn P1启动子，它们的突变并不影响核糖体RNA启动子的关闭过程。我们还测试了RpoS（已知在稳定期诱导许多基因的σ因子）的作用。结果表明，宿主因子Fis、H-NS和RpoS在rRNA合成关闭过程的调节中不发挥主要作用。所呈现的结果表明，rRNA合成速率为细菌培养物的生长阶段提供了一个灵敏的指标。
