Cooperative bending of the 21-base-pair repeats of the SV40 viral early promoter by human Sp1.
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.
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Drug Dynamics Institute, College of Pharmacy, University of Texas at Austin 78712-1074.
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D001483:Base Sequence; D004270:DNA, Circular / Q000378:metabolism; D004279:DNA, Viral / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D017665:Hydroxyl Radical; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012091:Repetitive Sequences, Nucleic Acid; D013539:Simian virus 40 / Q000235:genetics*; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D013329:Structure-Activity Relationship
D004270:DNA, Circular; D004279:DNA, Viral; D016329:Sp1 Transcription Factor; D017665:Hydroxyl Radical