Overstretching Double-Stranded RNA, Double-Stranded DNA, and RNA-DNA Duplexes.

Area of Science:

• Biophysics
• Molecular Biology
• Biochemistry

Background:

• Nucleic acid duplexes, DNA and RNA, exhibit distinct mechanical properties under force.
• Understanding these properties is crucial for comprehending their biological functions.

Purpose of the Study:

• To compare the overstretching transition of DNA and RNA duplexes using single-molecule force measurements.
• To elucidate the distinct mechanical behavior of double-stranded RNA (dsRNA) during overstretching.

Main Methods:

• Single-molecule force spectroscopy utilizing dual-beam optical trapping interferometry.
• Applied stretching force to DNA and RNA duplexes with beads attached to extremities.

Main Results:

• All four duplexes (DNA and RNA) underwent overstretching with minor variations in plateau forces.
• Double-stranded RNA (dsRNA) displayed a smooth overstretching transition, unlike the sawtooth patterns indicative of strand peeling in other duplexes.
• Theoretical modeling supported the absence of peeling and bubble formation in overstretching dsRNA.

Conclusions:

• dsRNA exhibits a unique overstretching mechanism, termed S-RNA, which avoids single-strand formation.
• This distinct property may facilitate RNA structure assembly and its essential cellular roles.
• The findings highlight fundamental differences in the mechanical behavior of DNA and RNA duplexes.