Transcription activation by a PNA-Peptide chimera in a mammalian cell extract

Synthetic activators that mimic the ability of native transcription factors to recruit the RNA polymerase holoenzyme to specific promoters could, in principle, be constructed by joining a sequence-specific DNA binding moiety with a molecule able to bind the holoenzyme. We report here that a peptide nucleic acid (PNA)-peptide chimera is capable of activating transcription in vitro in a HeLa nuclear extract. Specifically, a promoter-targeted PNA alone acts as a strong inhibitor of basal transcription in a HeLa nuclear extract, presumably due to structural modification of the promoter. However, the fusion of a Gal80-binding peptide to the PNA, but not control peptides, reactivates transcription. The Gal80-binding peptide was selected solely on the basis of its ability to bind the yeast repressor.