RNA adapts its flexibility to efficiently fold and resist unfolding

Area of Science:

• Biophysics
• Molecular Biology
• Nanotechnology

Background:

• Biopolymer structural dynamics are crucial for cellular functions.
• Experimental methods to resolve biomolecular structure interconversions are limited.
• Understanding RNA folding pathways is essential for deciphering biological mechanisms.

Purpose of the Study:

• To investigate the complete set of structural rearrangements in the UUCG stem-loop RNA.
• To resolve RNA interconversions between functionally relevant structures at the single-molecule level.
• To elucidate the mechanisms underlying RNA folding pathways and stability.

Main Methods:

• Utilized a nano-electronic device for single-molecule analysis.
• Achieved microsecond time resolution to capture rapid structural changes.
• Studied the ultra-stable UUCG stem-loop RNA.

Main Results:

• Identified at least four distinct conformations of the UUCG stem-loop.
• Discovered two folding pathways leading to two unique folded structures.
• Demonstrated that RNA can adaptively select folding pathways by modulating flexibility, enhancing stability and resistance to unfolding.

Conclusions:

• The UUCG stem-loop employs a mechanism of stabilization through compensatory changes in flexibility.
• This adaptive pathway selection enables rapid folding and resistance to unfolding.
• The findings suggest a generalizable strategy for biopolymer stabilization applicable to all biopolymers.