DNA recognition and induced genome modification by a hydroxymethyl-γ tail-clamp peptide nucleic acid
Stanley N. Oyaghire, Elias Quijano, Julián Perera, Hanna K. Mandl, W. Mark Saltzman, Raman Bahal, Peter M. Glazer
Abstract
Peptide nucleic acids (PNAs) can target and stimulate recombination reactions in genomic DNA. We have reported that γPNA oligomers possessing the diethylene glycol γ-substituent show improved efficacy over unmodified PNAs in stimulating recombination-induced gene modification. However, this structural modification poses a challenge because of the inherent racemization risk in O-alkylation of the precursory serine side chain. To circumvent this risk and improve γPNA accessibility, we explore the utility of γPNA oligomers possessing the hydroxymethyl-γ moiety for gene-editing applications. We demonstrate that a γPNA oligomer possessing the hydroxymethyl modification, despite weaker preorganization, retains the ability to form a hybrid with the double-stranded DNA target of comparable stability and with higher affinity than that of the diethylene glycol-γPNA. When formulated into poly(lactic-co-glycolic acid) nanoparticles, the hydroxymethyl-γPNA stimulates higher frequencies (≥1.5-fold) of gene modification than the diethylene glycol γPNA in mouse bone marrow cells.