Efficient DNA Photo Modulation by PNA-Rose Bengal Conjugates

Yossi Shemesh, Pharmacy School, HUJI, Jerusalem, Israel
Eylon Yavin, Pharmacy School, HUJI, Jerusalem, Israel

Design and discovery of chemical agents capable of sequence specific DNA modification is a challenge with a wide potential for the development of gene knockdown and gene repair technologies in molecular biology and medicine. Previous work in our lab, showed an efficient light induced plasmid cleavage by the combination of L-tryptophan (Trp) and a Thiazole orange (TO) conjugated to the N-terminus of a PNA (peptide nucleic acid) sequence. Mechanistic examinations suggested that singlet oxygen generated by the dye is not strong enough to damage the DNA directly, but can oxidize the Trp to an endoperoxide leading to DNA (plasmid) cleavage. In this work, we improved the system further by changing the photo-sensitizer to Rose Bengal (RB), which is known in the literature as potent singlet oxygen generator, used often in the research for photodynamic therapy (PDT) systems.

Interestingly, the new PNA conjugates present different mechanism of DNA damage; after irradiation, the generation of high concentrations of singlet oxygen lead to crosslinking as corroborated by slow migrating bands on a native polyacrlylamide gel. As RB emits in the Visible-NIR region it is a potential dye to be used in conjugation to PNA for site-specific DNA and RNA modulation in an in-vivo setting.