Novel three-dimensional 1H-13C-31P triple resonance experiments for sequential backbone correlations in nucleic acids

Area of Science:

• Biochemistry
• Structural Biology
• Nuclear Magnetic Resonance Spectroscopy

Background:

• Backbone-driven assignment methods using covalent connectivities are crucial for protein spectral assignments.
• Nucleic acid spectral assignments can benefit from 1H-13C-31P correlations, with related Heteronuclear Correlation (HCP) experiments recently developed for RNA.

Purpose of the Study:

• To present three-dimensional extensions of 1H-31P Heteronuclear Correlation (Het-Cor) and Heteronuclear Total Correlation Spectroscopy (Het-TOCSY) experiments.
• To complement existing HCP experiments for RNA spectral assignments and dihedral angle constraint extraction.
• To leverage 1H-31P couplings for improved spectral resolution and RNA structure determination.

Main Methods:

• Development and application of three-dimensional Het-Cor (P,H-COSY-H,C-HMQC) and Het-TOCSY (P,H-TOCSY-H,C-HMQC) experiments.
• Utilizing 1H-31P couplings, distinct from 13C-31P couplings, to generate cross peaks.
• Employing semiquantitative estimates of 1H-31P and 13C-31P couplings.

Main Results:

• The presented experiments provide complementary tools for spectral assignments in RNA.
• The use of 1H-31P couplings leads to cross peaks in different spectral regions, aiding in the resolution of spectral overlap.
• Semiquantitative coupling estimates yield valuable dihedral angle constraints for RNA structure determination.

Conclusions:

• The developed 3D Het-Cor and Het-TOCSY experiments enhance spectral assignment strategies for RNA.
• These NMR techniques improve spectral resolution and provide crucial data for accurate RNA structure determination.
• The methods facilitate the extraction of dihedral angle constraints, advancing the field of nucleic acid structural biology.