Mattern S G, Brawner M E, Westpheling J
Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia 19104.
J Bacteriol. 1993 Mar;175(5):1213-20. doi: 10.1128/jb.175.5.1213-1220.1993.
The galP1 promoter is responsible for galactose-dependent, glucose-sensitive transcription of the galactose utilization operon of Streptomyces coelicolor and Streptomyces lividans. We describe the characterization of mutations that were positioned directly upstream of the apparent transcription start site of galP1 and that resulted in deregulated expression. Certain combinations of base changes within a series of hexamers that lie within two pairs of direct repeat sequences resulted in significant expression from galP1 in the absence of inducer. These motifs are further implicated in regulation by the observation that DNA fragments containing the hexamers and direct repeat sequences resulted in increased transcription from the chromosomal copy of galP1 on multicopy plasmids in the absence of galactose. We suggest that these hexamers and direct repeat sequences constitute an operator for the negative regulation of the Streptomyces gal operon.
galP1启动子负责天蓝色链霉菌和淡紫链霉菌半乳糖利用操纵子的半乳糖依赖性、葡萄糖敏感性转录。我们描述了位于galP1明显转录起始位点上游且导致表达失调的突变的特征。位于两对直接重复序列内的一系列六聚体中的某些碱基变化组合，在没有诱导剂的情况下导致galP1显著表达。通过观察发现，含有六聚体和直接重复序列的DNA片段在没有半乳糖的情况下会导致多拷贝质粒上galP1染色体拷贝的转录增加，这些基序进一步参与了调控。我们认为这些六聚体和直接重复序列构成了链霉菌半乳糖操纵子负调控的操纵基因。
