Conformational deformability of RNA: a harmonic mode analysis.

Area of Science:

• Biophysics
• Structural Biology
• Computational Biology

Background:

• RNA molecules exhibit complex conformational dynamics crucial for their function.
• Understanding RNA flexibility is key to deciphering its biological roles and interactions.
• Previous studies have explored RNA dynamics, but detailed characterization of sequence and structural variations remains important.

Purpose of the Study:

• To characterize the conformational deformability of RNA with different structural features using harmonic mode analysis.
• To investigate the impact of mismatches, bulges, and specific base pairing arrangements on RNA flexibility.
• To correlate calculated atomic fluctuations with experimental data like Debye-Waller factors.

Main Methods:

• Harmonic mode analysis was employed to calculate atomic and helical coordinate fluctuations.
• Comparison of calculated atomic fluctuations with experimental atomic Debye-Waller factors from X-ray crystallography.
• Analysis of sequence dependence and correlation between motions at adjacent base pair steps.

Main Results:

• Good agreement was found between calculated atomic fluctuations and experimental Debye-Waller factors for regular RNA.
• RNA flexibility showed a small sequence dependence (30-50%) and negative correlation between adjacent base pair motions.
• Single mismatches had minor effects, while tandem G:A pairs and adenine bulges significantly altered local and global flexibility.

Conclusions:

• Harmonic mode analysis effectively characterizes RNA conformational deformability.
• RNA bending is primarily influenced by periodic changes in slide and roll descriptors.
• Specific structural variations like bulges and tandem base pairs can significantly modulate RNA flexibility, impacting its function.