EFFECT OF DNA-BINDING DRUGS ON EARLY GROWTH-RESPONSE FACTOR-I AND TATA BOX-BINDING PROTEIN COMPLEX-FORMATION WITH THE HERPES-SIMPLEX VIRUS LATENCY PROMOTER

Adjacent binding sites for early growth response factor-1 (EGR1) and T ATA box-binding protein (TBP) were identified on the herpes simplex vi rus latency promoter in previous work. The binding of EGR1 to the GC-r ich region prevented TBP binding to the AT-rich region. With the simul taneous addition of both EGR1 and TBP, the intercalator nogalamycin pr evented EGR1 complex formation, resulting in a dose-dependent increase of the TBP DNA complex. The minor groove binder chromomycin A(3) inhi bited EGR1 complex formation but resulted in a smaller increase of the TBP complex. In contrast, an alkylating intercalator hedamycin strong ly inhibited binding of both proteins. The ability of these GC-binding drugs to prevent EGR1 DNA complex formation was in the following orde r: hedamycin > nogalamycin > chro momycin A(3), and the specificity wa s nogalamycin > chromomycin A(3) > hedamycin, With transcription facto r IIA (TFIIA) in the assay, TBP was able to bind the promoter whereas formation of the EGR1 DNA complex was reduced. An AT minor groove-bind ing drug, distamycin A(3) disrupted the TBP TFIIA DNA complex and rest ored the EGR1 DNA complex. We conclude that the binding motif and sequ ence preference of DNA-interactive drugs are manifested in their abili ty to inhibit the transcription factor-DNA complexes.