Analysis of RNA flexibility by scanning force spectroscopy

Area of Science:

• Biophysics
• Molecular Biology
• Materials Science

Background:

• Understanding the mechanical properties of nucleic acids is crucial for molecular biology.
• Scanning force spectroscopy (SFS) offers a high-resolution method to probe single-molecule mechanics.
• Previous studies have characterized DNA's mechanical behavior, but RNA's properties are less understood.

Purpose of the Study:

• To compare the mechanical properties of double-stranded RNA (dsRNA) with double-stranded DNA (dsDNA) using SFS.
• To investigate the force-induced conformational transitions and stretching behavior of RNA.
• To explore the potential of SFS for analyzing RNA secondary structures.

Main Methods:

• Utilized scanning force spectroscopy to apply controlled forces to single RNA and DNA molecules.
• Measured force-distance curves to identify conformational changes and stretching.
• Analyzed the plateau force and S-factor (extension before melting) for both nucleic acid types.

Main Results:

• Identified a force-induced conformational transition in dsRNA, analogous to DNA's B-S transition, with force dependent on G+C content.
• Observed a higher and more variable S-factor for RNA (1.0 +/- 0.2) compared to DNA (0.7 +/- 0.2).
• Force spectroscopy on single-stranded RNA revealed diverse force-distance curves, indicating the stretching and disruption of various secondary structures.

Conclusions:

• dsRNA exhibits distinct mechanical stretching behavior compared to dsDNA, influenced by its sequence composition.
• SFS is a valuable technique for characterizing nucleic acid mechanics and has potential for detailed analysis of RNA secondary structures.
• Further instrumental improvements could enable precise mapping of RNA secondary structures using SFS.