FIG. 5.

Single-stranded 20rG and 29-dG oligonucleotides bind RNA polymerase II and inhibit transcription in the absence of other general transcription factors. (A) The 20rG and 29-dG oligonucleotides bind directly to RNA polymerase II. A ³²P-labeled 20rG oligonucleotide (0.5 pmol) and, where indicated, unlabeled oligonucleotides (1, 5, and 50 pmol) were incubated with RNA polymerase II (35 ng). The reaction in lane 1 lacked RNA polymerase. (B) The 20rG and 29-dG oligonucleotides inhibit transcription from a poly(dA-dT) · poly(dA-dT) template DNA. RNA polymerase II was added to reaction mixtures containing poly(dA-dT), ATP, UTP, and inhibitor oligonucleotides (250 nM). Transcription proceeded for 20 min. The nonspecific transcript is shown. (C) The 20rG oligonucleotide inhibits promoter-independent transcription with an IC₅₀ of 2.3 nM. Reactions were performed as described above. The nonspecific product was quantitated and plotted as shown.