A-tract and (+)-CC-1065-induced bending of DNA. Comparison of structural features using non-denaturing gel analysis, hydroxyl-radical footprinting, and high-field NMR.
(+)-CC-1065 is a biologically potent DNA-reactive antitumor antibiotic produced by Streptomyces zelensis. In a previous study we have reported that (+)-CC-1065 produces bending of DNA that has similarities to that intrinsically associated with A-tracts [Lin, C. H., Sun, D., & Hurley, L. H. (1991) Chem. Res. Toxicol, 4, 21-26]. In this article we provide evidence using a combination of non-denaturing gel analysis, hydroxyl-radical footprinting, and high-field NMR for both distinctions between the two types of bends and the importance of junctions in both types of bends. For A-tracts we demonstrate that the locus of bending is at the center of an A-tract and that upon modification of the 3' adenine with (+)-CC-1065 this locus is moved less than 1 base pair to the 3' side, and the bending magnitude is significantly increased. For drug bonding sequences such as 5'-AGTTA* or 5'-GATTA* (where * denotes the drug bonding site), the locus of bending is found to be between the two thymines, and the bending is focused over a 2-base-pair sequence rather than a 5-base-pair sequence, as is the case for the A-tract. An important distinction between an A-tract intrinsic bend and a (+)-CC-1065-induced bend is the effect of temperature. While, as shown previously, the magnitude of A-tract bending increases with decrease in temperature, for drug-induced bending of 5'-AGTTA* the bending magnitude increases with increased temperature.(ABSTRACT TRUNCATED AT 250 WORDS)
Sun
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D
Drug Dynamics Institute, College of Pharmacy, University of Texas, Austin 78712.
Lin
C H
CH
Hurley
L H
LH
D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000737:chemistry* / Q000187:drug effects* / Q000378:metabolism; D000080890:Duocarmycins; D004591:Electrophoresis, Polyacrylamide Gel; D006878:Hydroxides; D017665:Hydroxyl Radical; D007211:Indoles; D007933:Leucomycins / Q000378:metabolism / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D013302:Streptomyces; D013696:Temperature
D000080890:Duocarmycins; D006878:Hydroxides; D007211:Indoles; D007933:Leucomycins; D017665:Hydroxyl Radical; C018782:CC 1065; D004247:DNA