Inhibition of RNA polymerase II transcription by oligonucleotide-RecA protein filaments targeted to promoter sequences.

In the presence of RecA protein, which plays a major role in genetic recombination in Escherichia coli, an oligodeoxyribonucleotide can find its homologous counterpart in double-stranded DNA and form triple-stranded structures. A triple-stranded structure formed by an oligonucleotide with a sequence overlapping essential regulatory elements of a viral promoter, such as TATA or GC boxes, inhibited in vitro transcription driven by RNA polymerase II. An oligonucleotide with eight nucleotides homologous to its target suppressed RNA polymerase II activity in HeLa cell extracts. This procedure offers a potential alternative to the usual mutational analysis of transcriptional promoters.