Sun D, Hurley L H
Drug Dynamics Institute, College of Pharmacy, University of Texas at Austin 78712-1074.
Biochemistry. 1994 Aug 16;33(32):9578-87. doi: 10.1021/bi00198a025.
The overall structural features of the multimeric complex between Sp1 and the 21-base-pair repeat of the early promoter region of SV40 DNA have been determined using hydroxyl-radical footprinting; (+)-CC-1065, a sequence-specific minor groove bending probe; and circularization experiments. The results show that the 21-base-pair repeat region has an intrinsically in-phase bent structure that is stabilized upon saturation Sp1 binding by protein-DNA and protein-protein interactions to produce a looping structure. The direction of the Sp1-stabilized bending of DNA occurs into the minor groove and is localized between each of the Sp1 binding sites. These results are used as the basis to propose a looping structure for the multimeric Sp1 21-base-pair repeat region of SV40 DNA. Last, these results provide a rationale for the recently observed inhibition of basal transcriptional levels by site-specific triple-helical DNA complexes.
利用羟基自由基足迹法、序列特异性小沟弯曲探针（+）-CC-1065以及环化实验，确定了Sp1与SV40 DNA早期启动子区域21碱基对重复序列之间多聚体复合物的整体结构特征。结果表明，21碱基对重复区域具有固有的同相弯曲结构，在Sp1饱和结合时，通过蛋白质-DNA和蛋白质-蛋白质相互作用得以稳定，从而产生环状结构。Sp1稳定的DNA弯曲方向进入小沟，且定位在每个Sp1结合位点之间。这些结果作为依据，提出了SV40 DNA多聚体Sp1 21碱基对重复区域的环状结构。最后，这些结果为最近观察到的位点特异性三链DNA复合物对基础转录水平的抑制提供了理论依据。
