León P, Romero D, Garciarrubio A, Bastarrachea F, Covarrubias A A
J Bacteriol. 1985 Dec;164(3):1032-8. doi: 10.1128/jb.164.3.1032-1038.1985.
The spontaneous gln-76 mutation of Escherichia coli (Osorio et al., Mol. Gen. Genet. 194:114-123, 1984) was previously shown to be responsible for the cis-dominant constitutive expression of the glnA gene in the absence of a glnG-glnF activator system. Nucleotide sequence analysis has now revealed that gln-76 is a single transversion T.A to A.T, an up-promoter mutation affecting the -10 region of glnAp1, the upstream promoter of the glnALG control region. Both, wild-type and gln-76 DNA control regions were cloned into the promoter-probe plasmid pKO1. Galactokinase activity determinations of cells carrying the fused plasmids showed 10-fold more effective expression mediated by gln-76 than by the glnA wild-type control region. Primer extension experiments with RNA from strains carrying the gln-76 control region indicated that the transcription initiation sites were the same in both the gln-76 mutant and the wild type.
大肠杆菌的自发gln - 76突变（Osorio等人，《分子与普通遗传学》194:114 - 123，1984年）先前已表明，在缺乏glnG - glnF激活系统的情况下，它是glnA基因顺式显性组成型表达的原因。核苷酸序列分析现已揭示，gln - 76是一个单一的颠换T.A变为A.T，这是一个影响glnAp1（glnALG控制区域的上游启动子）-10区域的上启动子突变。野生型和gln - 76 DNA控制区域都被克隆到启动子探针质粒pKO1中。对携带融合质粒的细胞进行半乳糖激酶活性测定表明，由gln - 76介导的表达比glnA野生型控制区域有效10倍。对携带gln - 76控制区域的菌株的RNA进行引物延伸实验表明，gln - 76突变体和野生型的转录起始位点相同。
