Surface plasmon resonance study of PNA interactions with double-stranded DNA

Area of Science:

• Biochemistry
• Molecular Biology
• Biophysics

Background:

• Peptide nucleic acid (PNA) is a DNA analogue with a unique N-(2-aminoethyl)glycine backbone (aegPNA).
• PNA can bind to single-stranded nucleic acids and form higher-order complexes with double-stranded DNA (dsDNA) in a sequence-specific manner.
• Understanding PNA-dsDNA interactions is crucial for developing novel nucleic acid-based technologies.

Purpose of the Study:

• To report the first application of surface plasmon resonance (SPR) for studying PNA binding to dsDNA.
• To develop and validate SPR protocols for analyzing PNA-dsDNA interactions, including binding rules and conditions.
• To investigate the binding modes, kinetics, and efficiency of different PNA backbones with dsDNA.

Main Methods:

• Development of SPR protocols to study PNA binding to immobilized dsDNA.
• Verification of sequence rules and binding conditions (pH, ionic strength) for aegPNA-dsDNA interactions.
• Real-time SPR measurements to determine hybridization efficiency, binding direction, binding modes (triplex, duplex invasion), and kinetics.

Main Results:

• SPR protocols successfully characterized aegPNA binding to dsDNA, correlating well with solution-phase data.
• Hybridization efficiency, binding directionality, and sequence-dependent binding modes (triplex formation, duplex invasion) were ascertained.
• A conformationally rigid acpcPNA derivative was found unable to form higher-order complexes with dsDNA via triplex formation or duplex invasion.

Conclusions:

• SPR is a powerful technique for studying higher-order nucleic acid complexes, providing real-time kinetic and mechanistic insights.
• The developed SPR methods offer a robust platform for characterizing PNA-dsDNA interactions.
• The findings highlight the influence of PNA backbone structure on dsDNA binding complex formation.