Introducing novel building blocks to solid-phase peptide synthesis, we readily synthesized long-chain hairpin pyrrole-imidazole (PI) polyamide-chlorambucil conjugates 3 and 4 via the introduction of an amino group into a GABA (γ-turn) contained in 3, to target CAG/CTG repeat sequences, which are associated with various hereditary disorders. A high-resolution denaturing polyacrylamide sequencing gel revealed sequence-specific alkylation both strands at the N3 of adenines or guanines in CAG/CTG repeats by conjugates 3 and 4, with 11 bp recognition. In vitro transcription assays using conjugate 4 revealed that specific alkylation inhibited the progression of RNA polymerase at the alkylating sites. Chiral substitution of the γ-turn with an amino group resulted in higher binding affinity observed in SPR assays. These assays suggest that conjugates 4 with 11 bp recognition has the potential to cause specific DNA damage and transcriptional inhibition at the alkylating sites. © 2014 Elsevier Ltd. All rights reserved.
Asamitsu, S., Kawamoto, Y., Hashiya, F., Hashiya, K., Yamamoto, M., Kizaki, S., … Sugiyama, H. (2014). Sequence-specific DNA alkylation and transcriptional inhibition by long-chain hairpin pyrrole-imidazole polyamide-chlorambucil conjugates targeting CAG/CTG trinucleotide repeats. Bioorganic and Medicinal Chemistry, 22(17), 4646–4657. https://doi.org/10.1016/j.bmc.2014.07.019