Jones D H, Franklin F C, Thomas C M
School of Biological Sciences, University of Birmingham, UK.
Microbiology (Reading). 1994 May;140 ( Pt 5):1035-43. doi: 10.1099/13500872-140-5-1035.
The rpoN gene (encoding the sigma factor sigma 54) of Escherichia coli was cloned and its nucleotide sequence determined. Promoter probe analysis confirmed the presence of a promoter in a 350 bp fragment covering the start of rpoN. The likely promoter was identified. The nucleotide sequence of the region extending 2.1 kb downstream of rpoN was also determined. This region contained four open reading frames encoding potential polypeptides of 10750, 17959, 32492 and 9810 Da; maxicell and T7 promoter studies showed that four polypeptides of similar molecular masses were expressed from this region. The amino acid sequence of the 17959 Da polypeptide showed homology to the enzyme IIA domains of several proteins of the bacterial sugar phosphotransferase system (PTS), and the 9810 Da polypeptide showed homology to the HPr proteins of the bacterial PTS. The proteins encoded downstream of rpoN are known to negatively regulate sigma 54 activity. The homologies therefore suggest that this effect on sigma 54 may be mediated by sequential protein phosphorylation and suggest that there is a link between signal transduction and transcription of sigma 54-dependent genes.
克隆了大肠杆菌的rpoN基因（编码σ因子σ54）并测定了其核苷酸序列。启动子探针分析证实，在覆盖rpoN起始位点的350 bp片段中存在一个启动子。确定了可能的启动子。还测定了rpoN下游延伸2.1 kb区域的核苷酸序列。该区域包含四个开放阅读框，分别编码分子量为10750、17959、32492和9810 Da的潜在多肽；大细胞和T7启动子研究表明，该区域表达了四种分子量相似的多肽。17959 Da多肽的氨基酸序列与细菌糖磷酸转移酶系统（PTS）几种蛋白质的酶IIA结构域具有同源性，9810 Da多肽与细菌PTS的HPr蛋白具有同源性。已知rpoN下游编码的蛋白质对σ54活性具有负调控作用。因此，这些同源性表明，对σ54的这种作用可能是由顺序蛋白磷酸化介导的，并表明信号转导与σ54依赖性基因的转录之间存在联系。
