Importance of the position of TYR R boxes for repression and activation of the tyrP and aroF genes in Escherichia coli
Importance of the position of TYR R boxes for repression and activation of the tyrP and aroF genes in Escherichia coli
复制标题
TYR R 盒位置对于大肠杆菌中 tyrP 和 aroF 基因抑制和激活的重要性
作者：
A. E. Andrews;B. Dickson;B. Lawley;C. Cobbett;A. Pittard
酪氨酸介导的aroF和tyrP的阻遏通过在两个相邻的TYRR盒之间插入DNA序列来研究，在每种情况下，所述TYRR盒与这些基因的相应RNA聚合酶结合位点重叠。在这两种情况下，阻遏是最大的同源区域时，这两个TYR R盒是在同一面的DNA螺旋和盒直接相邻。插入3个碱基就足以消除阻遏，当盒子被螺旋的一整圈分开时，阻遏被重新建立。这些观察结果，再加上在体外DNA酶I保护研究的结果，支持的假设，TyrR蛋白的结合下游盒需要与TyrR蛋白已经结合到上游盒的合作相互作用。在tyrP的情况下，移动上游框也会影响激活。最大激活时，观察到的框移动3或12至14个残基上游。在中间位置，如+7和-4，几乎没有观察到激活。据推测，这些结果表明，允许结合到上游盒的TyrR蛋白和结合到RNA聚合酶结合位点的RNA聚合酶之间的最大相互作用的位置。
Tyrosine-mediated repression of aroF and tyrP was studied by inserting DNA sequences between the two adjacent TYR R boxes which, in each case, overlap the respective RNA polymerase binding sites of these genes. In both cases, repression was greatest when homologous regions of these two TYR R boxes were on the same face of the DNA helix and the boxes were directly adjacent. An insertion of 3 bases was sufficient to abolish repression, which was reestablished as the boxes became separated by one full turn of the helix. These observations, coupled with the results of in vitro DNase I protection studies, supported the hypothesis that the binding of TyrR protein to the downstream boxes required cooperative interaction with TyrR protein already bound to the upstream boxes. In the case of tyrP, moving the upstream box also affected activation. Maximal activation was observed when the box was moved 3 or 12 to 14 residues upstream. Practically no activation was seen at intermediate positions, such as +7 and -4. It is hypothesized that these results indicate positions allowing maximal interaction between TyrR protein bound to the upstream box and RNA polymerase bound to the RNA polymerase binding site.
DOI：
10.1073/pnas.84.14.4767
发表时间：
1987-07-01
影响因子：
11.1
作者：
TABOR, S;RICHARDSON, CC
通讯作者：
RICHARDSON, CC