Tovar K, Hillen W
Institut für Mikrobiologie und Biochemie der Friedrich-Alexander Universität Erlangen-Nürnberg, FRG.
Nucleic Acids Res. 1989 Aug 25;17(16):6515-22. doi: 10.1093/nar/17.16.6515.
Tet repressor dimer binds to two tet operator sites spaced by 30 bp in the Tn10 encoded tet regulatory DNA. The effect of repressor binding on the gel mobility of circular permutated DNA fragments containing either one or both operator sequences is reported. The EcoRI induced bending of DNA is used to compare the results with other protein binding induced structural perturbations of DNA. Tet repressor bends a DNA fragment with a single tet operator to an angle of 42 degrees +/- 7 degrees. The apparent bend angle of DNA fragments containing the tandem tet operator arrangement occupied by two Tet repressor dimers turns out to be 52 degrees +/- 9 degrees. These results are interpreted with respect to the end to end distances of the bent DNA fragments. They indicate that either the intervening tet regulatory DNA between the operators or the bound operator sequences themselves contain additional perturbations from the canonical B-DNA structure. This finding is discussed in the light of previously obtained results from CD, neutron scattering, and electrooptical studies.
四环素阻遏物二聚体与Tn10编码的四环素调控DNA中相隔30个碱基对的两个四环素操纵子位点结合。本文报道了阻遏物结合对含有一个或两个操纵序列的环形置换DNA片段凝胶迁移率的影响。利用EcoRI诱导的DNA弯曲，将结果与其他蛋白质结合诱导的DNA结构扰动进行比较。四环素阻遏物将含有单个四环素操纵子的DNA片段弯曲至42度±7度的角度。由两个四环素阻遏物二聚体占据的含有串联四环素操纵子排列的DNA片段的表观弯曲角度为52度±9度。这些结果根据弯曲DNA片段的端到端距离进行解释。它们表明，操纵子之间的中间四环素调控DNA或结合的操纵序列本身都包含来自典型B-DNA结构的额外扰动。结合先前从圆二色性、中子散射和电光研究中获得的结果对这一发现进行了讨论。
