Inhibition of the bovine papillomavirus E2 protein activity by peptide nucleic acid

The bovine papillomavirus type-1 E2 protein is the master regulator of the papillomavirus transcription and replication, the activity of which is regulated through sequence-specific DNA binding. Peptide nucleic acid (PNA) is a nucleic acid analogue, which associates with high affinity to complementary DNA, RNA or PNA, yielding in formation of stable complexes. The potential use of PNA as a sequence-specific inhibitor of the E2 protein activity is studied in this report. We demonstrate that replacement of one or both DNA strands with the complementary PNA reduced drastically the affinity of the BPV-1 E2 protein to its target site in the direct as well as in competitive binding as shown by in vitro gel-shift assays. We demonstrate that PNA could specifically bind to the double stranded E2 binding site by forming the complex with DNA oligonucleotide. In addition, PNA was able to bind specifically to the E2 binding site within the supercoiled plasmid DNA. Such binding of PNA to the E2 binding site within the origin of replication specifically abolished the activity of the E2 protein in the initiation of DNA replication in vivo.