Boronated Condensed DNA as a Heterochromatic Radiation Target Model

The compound 4-dihydroxyboryl-L-phenylalanine (BPA) has found use in clinical trials of boron neutron capture therapy (BNCT). Here, we have examined the interaction with DNA of an amide-blocked BPA derivative of hexa-L-arginine (Ac-BPA-Arg(6)-NH2). Physical and spectroscopic assays show that this peptide binds to and condenses DNA. The resulting condensates are highly resistant to the effects of nuclease incubation (68-fold) and gamma (38-fold) irradiation. Radioprotection was modeled by Monte Carlo track structure simulations of DNA single strand breaks (SSBs) with TOPAS-nBio. The differences between experimental and simulated SSB yields for uncondensed and condensed DNAs were ca. 2 and 18%, respectively. These observations indicate that the combination of a plasmid DNA target, the BPA-containing peptide, and track structure simulation provides a powerful approach to characterize DNA damage by the high-LET radiation associated with neutron capture on boron.

Automated summary

The study explored the interaction between a new BPA derivative peptide and DNA, which resulted in DNA condensation and high resistance to nucleases and radiation. By using track structure simulations, it was found that the peptide could effectively protect DNA from single strand breaks, providing a powerful approach to characterize DNA damage caused by high-LET radiation associated with boron neutron capture.