TRIPLEX FORMING ABILITY OF A C-MYC PROMOTER ELEMENT PREDICTS PROMOTERSTRENGTH

Most transcription factors are believed to bind promoter elements in t he B-DNA conformation, wherein linear sequence determines specificity. However, there are promoter elements that can form complex structures such as intramolecular triplexes, and these structures may participat e in the activity of these promoter elements. We have previously shown that a c-myc promoter element, termed the nuclease-sensitive element or NSE, can form tandem intramolecular triplexes of the H-DNA type and has a repeating sequence motif (ACCCTCCCC)4. The NSE was mutated and examined for transcriptional activity and for intra- and intermolecula r triplex forming ability. The transcriptional activity of mutant NSEs can be predicted by the element's ability to form H-DNA and not by re peat number, position, or the number of mutant base pairs. DNA may the refore be a dynamic participant in the transcription of the c-myc gene . (C) 1994 Academic Press, Inc.