Binding of Sp1 to the 21-bp repeat region of SV40 DNA: effect of intrinsic and drug-induced DNA bending between GC boxes.
The effect of the antitumor antibiotic (+)-CC-1065 on the binding of Sp1 to the 21-bp repeats of SV40 DNA has been investigated. (+)-CC-1065 alkylates N3 of adenine in DNA and resides in the minor groove. As a consequence of alkylation of the two 5'-AGTTA* sequences (* indicates covalent modification site), which reside between GC boxes III and IV, and boxes V and VI, protein binding to the 3' sites is completely abolished and there is a significant decrease in Sp1 binding to the other regions. The effect of substituting A5 tracts for the (+)-CC-1065-bonding sequence was intermediate between the unmodified 5'-AGTTA* and the drug-modified sequences. It is proposed that a structural distortion of DNA associated with stiffening of the helix induced by the drug-adduct formation is primarily responsible for the inhibition of binding of Sp1 molecules to 21-bp repeats, rather than steric hindrance due to the occupancy by drug molecules of the minor groove within that region.
Drug Dynamics Institute, College of Pharmacy, University of Texas at Austin, 78712-1074.
D
D
Sun
L H
LH
Hurley
D001483:Base Sequence; D004279:DNA, Viral / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism*; D003850:Deoxyribonuclease I; D000080890:Duocarmycins; D007211:Indoles; D007933:Leucomycins / Q000494:pharmacology; D008969:Molecular Sequence Data; D015394:Molecular Structure; 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*
D004279:DNA, Viral; D000080890:Duocarmycins; D007211:Indoles; D007933:Leucomycins; D016329:Sp1 Transcription Factor; C018782:CC 1065; D003850:Deoxyribonuclease I