Specific Signal Enhancement on an RNA-Protein Interface by Dynamic Nuclear Polarization

Area of Science:

• Biochemistry
• Structural Biology
• Nuclear Magnetic Resonance (NMR) Spectroscopy

Background:

• Efficient structure determination of large biomolecules using solid-state NMR requires high sensitivity and specificity.
• Ribonucleoprotein (RNP) complexes present challenges due to their size and complexity.

Purpose of the Study:

• To develop an approach that enhances both sensitivity and specificity in solid-state NMR for RNP complexes.
• To site-specifically enhance NMR signals at the protein-RNA binding interface using Dynamic Nuclear Polarization (DNP).

Main Methods:

• Utilized sparse isotope labeling techniques for selective labeling of protein methyl groups with Carbon-13 (¹³C).
• Exploited the molecular dynamics of ¹³C-labeled methyl groups to drive heteronuclear cross-relaxation.
• Applied DNP to transfer hyperpolarization across the protein-RNA interface.

Main Results:

• Demonstrated site-specific polarization transfer from protein methyl groups to the RNA in an L7Ae-box C/D RNP complex.
• Identified a single methyl-nucleotide contact as the primary source of polarization transfer.
• Showcased the ability of DNP to significantly boost NMR spectral sensitivity and specificity.

Conclusions:

• The presented DNP-based approach effectively enhances NMR signal detection at specific biomolecular interfaces.
• This method offers a powerful tool for the structure determination of large RNP complexes.
• Site-specific hyperpolarization transfer improves the efficiency and accuracy of solid-state NMR studies.