Perisic O, Xiao H, Lis J T
Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853.
Cell. 1989 Dec 1;59(5):797-806. doi: 10.1016/0092-8674(89)90603-x.
The minimal DNA sequence required for the formation of a stable complex with Drosophila heat shock factor (HSF) in vitro is an inverted repeat of a 5 bp recognition unit, -GAA-. Surprisingly, both permutations of this 5 bp unit, head-to-head and tail-to-tail, bind to HSF with similar affinity and with striking 2-fold symmetry. HSF also binds to longer arrays of inverted 5 bp units, and the size of the HSF footprint increases with the addition of each 5 bp unit to these arrays. However, the electrophoretic mobility of the HSF-DNA complexes decreases most distinctly with the addition of every three 5 bp units. Cross-linking of purified HSF in the absence of DNA generates complexes with the sizes expected of HSF trimers. We propose that trimers of HSF bind to DNA and that the number of HSF subunits in direct contact with DNA is determined by the number of correctly positioned 5 bp recognition units.
在体外与果蝇热休克因子（HSF）形成稳定复合物所需的最小DNA序列是一个5 bp识别单元-GAA-的反向重复序列。令人惊讶的是，这个5 bp单元的两种排列方式，头对头和尾对尾，都以相似的亲和力与HSF结合，并具有显著的2倍对称性。HSF还能与更长的5 bp反向重复单元阵列结合，并且随着这些阵列中每增加一个5 bp单元，HSF足迹的大小也会增加。然而，随着每增加三个5 bp单元，HSF-DNA复合物的电泳迁移率下降最为明显。在没有DNA的情况下对纯化的HSF进行交联会产生预期大小的HSF三聚体复合物。我们提出HSF三聚体与DNA结合，并且与DNA直接接触的HSF亚基数量由正确定位的5 bp识别单元的数量决定。
