A model system for investigating lineshape/structure correlations in RNA site-directed spin labeling

Area of Science:

• Biochemistry and Molecular Biology
• Structural Biology
• Biophysics

Background:

• Site-directed spin labeling (SDSL) provides insights into RNA structure and dynamics at the nucleotide level via electron paramagnetic resonance (EPR) spectroscopy.
• A systematic library correlating spectral lineshapes with known RNA structures is needed for efficient structure identification.

Purpose of the Study:

• To establish the foundational elements for the first RNA SDSL library.
• To enable lineshape-based structure identification across various RNA sites.

Main Methods:

• Engineered specific secondary structure elements into a model RNA.
• Utilized a novel avidin-tethering method to minimize spectral interference from uniform RNA tumbling.
• Obtained nitroxide lineshapes characteristic of distinct structural elements.

Main Results:

• Demonstrated spectral divergence, where different RNA elements yield distinctive lineshapes.
• Showcased spectral convergence, indicating similar lineshapes for identical elements in varied contexts.
• Validated the two key features essential for a predictive SDSL library.

Conclusions:

• The developed methodology provides a robust foundation for building a comprehensive RNA SDSL library.
• This approach facilitates accurate RNA structure and dynamics determination at the individual nucleotide level.
• The findings pave the way for advanced RNA structural studies using SDSL.