Sequence Selective Recognition of Double-Stranded RNA at Physiologically Relevant Conditions Using PNA-Peptide Conjugates

Conjugation of short peptide nucleic acids (PNA) with tetralysine peptides strongly enhanced triple helical binding to RNA at physiologically relevant conditions. The PNA hexamers and heptamers carrying cationic nucleobase and tetralysine modifications displayed high binding affinity for complementary double-stranded RNA without compromising sequence selectivity. The PNA-peptide conjugates had unique preference for binding double-stranded RNA, while having little, if any, affinity for double-stranded DNA. The cationic PNAs were efficiently taken up by HEK293 cells, whereas little uptake was observed for unmodified PNA.