Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany.
RNA Biol. 2010 Sep-Oct;7(5):564-8. doi: 10.4161/rna.7.5.12969. Epub 2010 Sep 1.
Bacterial 6S RNA has been shown to bind with high affinity to σ(70)-containing RNA polymerase, suppressing σ(70)-dependent transcription during stationary phase, when 6S RNA concentrations are highest. We recently reported a genome-wide transcriptional comparison of wild-type and 6S RNA deficient E. coli strains. Contrary to the expected σ(70)- and stationary phase-specific regulatory effect of 6S RNA it turned out that mRNA levels derived from many alternative sigma factors, including σ(38) or σ(32), were affected during exponential and stationary growth. Among the most noticeably down-regulated genes at stationary growth are ribosomal proteins and factors involved in translation. In addition, a striking number of mRNA levels coding for enzymes involved in the purine metabolism, for transporters and stress regulators are altered both during log- and stationary phase. During the study we discovered a link between 6S RNA and the general stress alarmone ppGpp, which has a higher basal level in cells deficient in 6S RNA. This finding points to a functional interrelation of 6S RNA and the global network of stress and growth adaptation.
细菌 6S RNA 已被证明能与含有 σ(70)的 RNA 聚合酶高亲和力结合，在静止期（6S RNA 浓度最高时）抑制 σ(70)依赖的转录。我们最近报道了野生型和 6S RNA 缺陷型大肠杆菌菌株的全基因组转录比较。与预期的 6S RNA 的 σ(70)和静止期特异性调节作用相反，结果表明许多替代 σ 因子（包括 σ(38)或 σ(32)）的 mRNA 水平在指数和静止生长期间受到影响。在静止生长时下调最明显的基因是核糖体蛋白和参与翻译的因子。此外，大量编码参与嘌呤代谢、转运蛋白和应激调节剂的酶的 mRNA 水平在对数期和静止期都发生了改变。在研究过程中，我们发现 6S RNA 与一般应激感应鸟苷四磷酸（ppGpp）之间存在联系，在缺乏 6S RNA 的细胞中，ppGpp 的基础水平更高。这一发现表明 6S RNA 与应激和生长适应的全球网络之间存在功能关联。
