Efficient pH-independent sequence-specific DNA binding by pseudoisocytosine-containing bis-PNA

Area of Science:

• Synthetic chemistry
• Molecular biology
• Biochemistry

Background:

• Peptide nucleic acids (PNAs) are DNA analogs with potential in diagnostics and therapeutics.
• Developing PNAs with improved DNA binding affinity and stability is crucial for their applications.

Purpose of the Study:

• To synthesize and characterize novel bis-PNA molecules.
• To evaluate the DNA binding properties and thermal stability of these bis-PNAs.
• To compare the efficacy of bis-PNAs with monomeric PNAs in targeting DNA.

Main Methods:

• Continuous synthesis of bis-PNAs using a flexible linker of 8-amino-3,6-dioxaoctanoic acid units.
• Formation of triple-stranded complexes with complementary oligonucleotides.
• Thermal melting studies to assess complex stability and hysteresis.
• pH-dependent and independent DNA binding assays.
• Evaluation of strand invasion into double-stranded DNA.

Main Results:

• Successfully synthesized bis-PNAs with defined sequences and flexible linkers.
• Bis-PNAs formed triple-stranded complexes with higher thermal stability compared to monomeric PNAs.
• Minimal hysteresis was observed in the thermal melting transitions.
• pH-independent DNA binding was achieved when pseudoisocytosine (J) was incorporated into the Hoogsteen strand.
• Bis-PNAs demonstrated superior performance over monomeric PNAs in targeting double-stranded DNA via strand invasion.

Conclusions:

• Bis-PNAs represent a promising class of nucleic acid analogs with enhanced DNA binding properties.
• The flexible linker and specific base modifications contribute to improved thermal stability and pH-independent binding.
• Bis-PNAs show potential for more effective targeting of double-stranded DNA compared to their monomeric counterparts.