Actinomycin D induced DNase I hypersensitivity and asymmetric structure transmission in a DNA hexadecamer

DNase I cleavage rates and nmr chemical shifts are shown to change for DNA sequences distal to an intercalated actinomycin D molecule in a duplex hexadecamer upon drug binding. Both sets of observations suggest that the source of these changes is a DNA-mediated structural response. The nmr results imply the response is transmitted preferentially in a 5′-to-3′ direction from the drug binding site. An inequivalent response of the two strands to a ligandinduced conformational change immediately suggests a mechanism for distinguishing the sense and antisense strands of DNA.