Studying the Potassium-Induced G-Quadruplex DNA Folding Process Using Microscale Thermophoresis

Area of Science:

• Biochemistry
• Molecular Biology
• Biophysics

Background:

• Guanine quadruplexes (G4s) are formed by G-rich DNA sequences, stabilized by cations like potassium (K+).
• G4s play critical roles in DNA replication, recombination, transcription, and telomere maintenance.
• Understanding G4 folding pathways and ion interactions is essential for elucidating their cellular functions, but remains incomplete.

Purpose of the Study:

• To investigate Guanine quadruplex-potassium ion (G4-K+) interactions and folding pathways.
• To characterize the binding parameters and identify energetically favorable folding/unfolding pathways for G4s.
• To provide a framework for studying DNA-ion interactions experimentally.

Main Methods:

• Utilized microscale thermophoresis (MST) to monitor simultaneous changes in charge and size during G4-K+ interactions.
• Measured and calculated basic binding parameters for G4-K+ interactions.
• Analyzed equilibrium dissociation constants for ten potential folding intermediates.

Main Results:

• Clearly distinguished and precisely fitted two K+ binding states for the human telomeric G4 (hTG4).
• Quantified fundamental binding parameters governing G4-K+ interactions.
• Proposed energetically favorable folding/unfolding pathways based on analyzed intermediate dissociation constants.

Conclusions:

• The study provides novel insights into G4-K+ interactions and G4 folding mechanisms.
• Identified specific binding states and pathways, advancing the understanding of G4 structure-function relationships.
• Demonstrates the utility of MST for studying DNA-ion interactions and G4 folding dynamics.