Identifying hydrogen bond alignments in multistranded DNA architectures by NMR

Area of Science:

• Structural Biology
• Biophysical Chemistry
• Nuclear Magnetic Resonance (NMR) Spectroscopy

Background:

• Trans-hydrogen-bond scalar coupling constants significantly advance NMR studies of nucleic acids.
• Direct determination of N-H...N and N-H...O=C hydrogen bonds is crucial for understanding DNA structure.
• Multistranded DNA architectures with mismatched base pairing present significant identification challenges.

Purpose of the Study:

• To present novel NMR pulse sequences for addressing challenges in identifying hydrogen bonds in complex DNA.
• To demonstrate the utility of these methods for analyzing intricate hydrogen-bonded networks.

Main Methods:

• Utilized a combination of (2h)J(NN)-, (4h)J(NN)-, and (3h)J(NC)-based spectroscopy.
• Developed and applied a suite of specialized NMR pulse sequences.
• Investigated hydrogen bond identification in quadruplex DNA structures.

Main Results:

• Successfully identified N-H...N and N-H...O=C hydrogen bonds using the developed NMR techniques.
• Demonstrated the application of these methods in two quadruplex DNA structures.
• Characterized hydrogen bonds within triad, tetrad, and hexad motifs, including mismatched base pairs (Watson-Crick, G.G, sheared G.A).

Conclusions:

• The developed NMR pulse sequences effectively overcome technical and spectroscopic challenges in analyzing complex DNA.
• These methods provide a powerful tool for precise hydrogen bond determination in intricate nucleic acid structures.
• Enables detailed structural insights into quadruplex DNA containing various base pairing motifs.