Cabrera J E, Jin D J
Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
J Bacteriol. 2001 Oct;183(20):6126-34. doi: 10.1128/JB.183.20.6126-6134.2001.
The Escherichia coli rapA gene encodes the RNA polymerase (RNAP)-associated protein RapA, which is a bacterial member of the SWI/SNF helicase-like protein family. We have studied the rapA promoter and its regulation in vivo and determined the interaction between RNAP and the promoter in vitro. We have found that the expression of rapA is growth phase dependent, peaking at the early log phase. The growth phase control of rapA is determined at least by one particular feature of the promoter: it uses CTP as the transcription-initiating nucleotide instead of a purine, which is used for most E. coli promoters. We also found that the rapA promoter is subject to growth rate regulation in vivo and that it forms intrinsic unstable initiation complexes with RNAP in vitro. Furthermore, we have shown that a GC-rich or discriminator sequence between the -10 and +1 positions of the rapA promoter is responsible for its growth rate control and the instability of its initiation complexes with RNAP.
大肠杆菌rapA基因编码与RNA聚合酶（RNAP）相关的蛋白RapA，它是SWI/SNF类解旋酶蛋白家族的细菌成员。我们研究了rapA启动子及其体内调控，并在体外确定了RNAP与该启动子之间的相互作用。我们发现rapA的表达依赖于生长阶段，在对数早期达到峰值。rapA的生长阶段调控至少由启动子的一个特定特征决定：它使用CTP作为转录起始核苷酸，而不是大多数大肠杆菌启动子所使用的嘌呤。我们还发现rapA启动子在体内受生长速率调控，并且在体外与RNAP形成内在不稳定的起始复合物。此外，我们已经表明，rapA启动子-10和+1位置之间富含GC的序列或鉴别序列负责其生长速率控制以及与RNAP形成的起始复合物的不稳定性。
