Carra J H, Schleif R F
Biology Department, Johns Hopkins University, Baltimore, MD 21218.
Nucleic Acids Res. 1993 Feb 11;21(3):435-8. doi: 10.1093/nar/21.3.435.
With the use of special DNA binding sites, but not the natural aral binding site, the dimeric AraC protein can be forced to make sandwich structures in which two DNA molecules are joined by two AraC protein dimers. Apparently one subunit from each dimer contacts each DNA molecule in an extended structure. These sandwich structures form only in the absence of arabinose. This behavior is consistent with the protein's ability to form DNA loops by binding to separated half sites in the absence of arabinose and its preference for binding to adjacent half-sites in the presence of arabinose.
通过使用特殊的DNA结合位点，而非天然的阿拉伯糖结合位点，可以迫使二聚体AraC蛋白形成夹心结构，其中两个DNA分子由两个AraC蛋白二聚体连接。显然，每个二聚体中的一个亚基在伸展结构中与每个DNA分子接触。这些夹心结构仅在没有阿拉伯糖的情况下形成。这种行为与该蛋白在没有阿拉伯糖时通过结合分离的半位点形成DNA环的能力以及在有阿拉伯糖时优先结合相邻半位点的特性相一致。
