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

Abstract

(+)-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)

CC-1065 and the duocarmycins: unraveling the keys to a new class of naturally derived DNA alkylating agents.

“…More recently, the DNA binding properties ofACDPIn (15; n = 1-4) and TACDPIn 1NMe3 -7.6 -9.8 -t 1 .1I the natural enantiomers has been attributed to a sequence-dependent activation through C4 carbonyl protonation by a strategically positioned phosphate in the DNA backbone (35-38, 55, 56), the conformational variability of DNA and alkylation at junctions of bent DNA (67)(68)(69), or preferential noncovalent binding and subsequent alkylation within the narrower, deeper minor groove of AT-rich DNA (27)(28)(29)(30)(31)(32)(33)(34). Central to the interpretations are the perceived similarities (35)(36)(37)(38)(39)(53)(54)(55)(56) or distinctions (27-34, 42, 43) in the alkylation selectivity of simple derivatives including 11-12 and the natural products 1-3.…”

Specific targeting of protein–DNA complexes by dna-reactive drugs (+)-CC-1065 and pluramycins

“…Only one 72-bp enhancer is shown. (Reprinted with permission from American Chemical Society (Sun and Hurley, 1994.)) McKnight, 1989;Mitchell and Tjian, 1989;Muller and Schaffner, 1990;Ptashne, 1988).…”

“…(Reprinted with permission from American Chemical Society (Sun and Hurley, 1994. )) protein interactions between DNA-bound Sp 1 molecules and other transcriptional factors (Courey et al, 1989).…”

“…Other systems (see Discussion section) have been identified where the interactions between DNA-reactive compounds and DNA have the potential to influence transcription. This review summarizes earlier published results from this laboratory which examined two ternary complexes involving transcriptional factor proteins: the SpI-GC box complex targeted with the antitumor agent (+)-CC-1065 (Sun and Hurley, 1994) and the TATA binding protein (TBP)-TATA box complex targeted with the intercalating agent pluramycin .…”

A simple ligation assay to detect effects of drugs on the curvature/flexibility of DNA

“…The antibiotics actinomycin and mithramycin, which are frequently used in chemotherapy of cancer, bend the DNA into the major groove upon binding to the minor groove of GC-rich sequences [8,9]. On the other hand, the antibiotic CC-1065 bends the helix axis towards the minor groove upon covalent attachment into that groove [10,11]. Other antitumour drugs such as ditercalinium and bizelesin can recognize and straighten out bent DNA [12,13] …”