Impact of bPNA Backbone Structural Constraints and Composition on Triplex Hybridization with DNA

Area of Science:

• Biochemistry
• Molecular Biology
• Synthetic Chemistry

Background:

• Peptide nucleic acids (PNAs) are DNA mimics with potential in diagnostics and therapeutics.
• Bifacial PNAs (bPNA) offer unique structural properties for DNA binding.
• Understanding factors influencing bPNA-DNA hybrid stability is crucial for their application.

Purpose of the Study:

• To investigate the impact of bPNA amino acid composition and backbone modifications on DNA binding affinity and hybrid stability.
• To explore strategies for preorganizing bPNA structures to enhance DNA binding.
• To establish structure-stability relationships in bPNA-DNA interactions.

Main Methods:

• Synthesis of bPNA backbone variants with varying melamine (M) base content (4M and 6M).
• Creation of T-rich DNA sequences for forming thymine-melamine-thymine (TMT) base-triples.
• Structural preorganization of bPNAs using double-click covalent stapling and incorporation of fluorinated prolines.
• Analysis of bPNA-DNA hybrid stability through biophysical methods.

Main Results:

• Hybrid stability in 6M bPNA-DNA was linked to amino acid secondary structure propensities.
• Covalent stapling generally improved hybrid stability in 4M bPNAs, but amino acid composition had a greater effect.
• Incorporation of fluoroprolines significantly enhanced bPNA-DNA hybrid stability beyond other modifications.

Conclusions:

• bPNA-DNA hybrid stability is tunable through strategic modification of the bPNA backbone and amino acid sequence.
• Structural preorganization, particularly with fluorinated prolines, offers a powerful approach to enhance bPNA-DNA interactions.
• These findings provide a foundation for designing novel bPNA-based molecules with tailored DNA binding properties.