Nucleobase and Linker Modification for Triple-Helical Recognition of Pyrimidines in RNA Using Peptide Nucleic Acids

Area of Science:

• Chemical Biology
• Molecular Biology
• Biochemistry

Background:

• Triple-helical recognition of double-stranded RNA is crucial for various biological processes.
• Hoogsteen hydrogen bonding is essential for this recognition, but pyrimidine bases pose a challenge due to limited hydrogen bonding capabilities.

Purpose of the Study:

• To investigate modifications in peptide nucleic acid (PNA) structures to improve triple-helical recognition of RNA.
• To optimize the formation of specific triplets (X•C-G and Y•U-A) by exploring heterocyclic nucleobases and linker modifications.

Main Methods:

• Utilized molecular modeling to predict binding interactions.
• Employed biophysical techniques, including UV melting and isothermal titration calorimetry, to assess binding affinity and selectivity.

Main Results:

• Five-membered heterocyclic nucleobases did not enhance pyrimidine recognition in triple-helical structures.
• Increasing the linker length by four atoms in the PNA backbone significantly improved binding affinity and selectivity.
• A complex relationship exists between heterocyclic nucleobase choice and linker length in PNA.

Conclusions:

• Modifying linker length in PNA is a more effective strategy than using simple heterocycles for improving pyrimidine recognition in triple-helical RNA binding.
• Further optimization of PNA structures, particularly through extended linkers and advanced heterocyclic bases, holds promise for achieving specific RNA triple-helical recognition.