Polyamines alter sequence-specific DNA-protein interactions

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Abstract
The polyamines are abundant blogenlc cations implicated in many biological processes. Despite a plethora of evidence on polyamine-induced DNA conforma-tional changes, no thorough study of their effects on the activities of sequence-specific DNA binding proteins has been performed. We describe the In vitro effects of polyamines on the activities of purified, representative DNA-binding proteins, and on complex protein mixtures. Polyamines at physiological concentrations enhance the binding of several proteins to DNA (e.g. USF, TFE3, Ig/EBP, NF-IL6, YY1 and ICP-4, a herpes simplex virus gene regulator), but Inhibit others (e.g. Oct-1). The degree of enhancement correlates with catlonic charge; divalent putrescine is ineffective whereas tetravalent spermine is more potent than trlvalent spermldine. Polyamine effects on USF and ICP-4 result from increased rate of complex formation rather than a decreased rate of dissociation. DNAse I footprint analysis Indicated that polyamines do not alter DNA-proteln contacts. Polyamines also facilitate formation of complexes involving binding of more than one protein on a DNA fragment.