Lamond A I, Travers A A
Nature. 1983;305(5931):248-50. doi: 10.1038/305248a0.
Bacterial promoters are the sites at the 5' end of each gene that bind RNA polymerase and direct the initiation of transcription. The functional elements of Escherichia coli promoters are two highly conserved sequences, each about six nucleotides long, usually centred at sites -10 and -35, +1 being the initiating nucleotide. We have been interested in the structure of promoters of genes that are subject to stringent control, that is whose expression is reduced in conditions of amino acid shortage, such as rRNA and tRNA genes. We have therefore mapped the sequences involved in promoting in vivo transcription of a bacterial tRNATyr (tyrT) gene by fusing the tyrT promoter region to a galactokinase (galK) gene, and using in vivo expression of galactokinase activity to measure promoter strength. We show here that efficient expression from the tyrT promoter requires specific sequences upstream of the canonical promoter elements, and we suggest that these sequences constitute an extended promoter structure.
细菌启动子位于每个基因的5'端，是与RNA聚合酶结合并指导转录起始的位点。大肠杆菌启动子的功能元件是两个高度保守的序列，每个序列约六个核苷酸长，通常位于-10和-35位点的中心，+1为起始核苷酸。我们一直对受到严格控制的基因启动子结构感兴趣，即在氨基酸短缺的条件下其表达会降低的基因，如rRNA和tRNA基因。因此，我们通过将tyrT启动子区域与半乳糖激酶（galK）基因融合，并利用半乳糖激酶活性的体内表达来测量启动子强度，绘制了参与细菌tRNATyr（tyrT）基因体内转录促进的序列。我们在此表明，tyrT启动子的高效表达需要在经典启动子元件上游的特定序列，并且我们认为这些序列构成了一种扩展的启动子结构。
