Fluorescence detection of potassium ion using the G-quadruplex structure

Area of Science:

• Biochemistry
• Molecular Biology
• Chemical Biology

Background:

• Oligonucleotides, such as human telomere DNA and thrombin binding aptamer (TBA), can form stable tetraplex structures. These structures are notably influenced by the presence of potassium (K+) ions.
• The structural transitions of these oligonucleotides upon K+ binding have been explored for biosensing applications.

Purpose of the Study:

• To develop and characterize potassium-sensing oligonucleotide (PSO) probes for monitoring potassium ion concentrations.
• To investigate the potential of these probes for fluorescence imaging of potassium gradients in biological systems.
• To explore the detection of human telomere DNA tetraplex polymorphism.

Main Methods:

• Development of PSO probes by conjugating two fluorescent dyes to the termini of specific oligonucleotides.
• Utilizing fluorescence resonance energy transfer (FRET) and excimer emission for signal transduction.
• Employing fluorescence techniques to monitor structural changes upon K+ binding.
• Testing probe selectivity for K+ over sodium (Na+) ions.

Main Results:

• The developed PSO probes demonstrated a high preference for K+ ions over Na+ ions.
• The probes successfully enabled fluorescence-based monitoring of structural changes induced by K+ binding.
• The system showed potential for fluorescence imaging of intracellular potassium concentration gradients.
• Polymorphism in human telomere DNA tetraplex structures could be followed using this method.

Conclusions:

• PSO probes offer a selective and sensitive method for detecting potassium ions.
• These probes are suitable for real-time fluorescence imaging of potassium dynamics in living cells.
• The approach can also be applied to study the structural diversity of DNA tetraplexes, such as those formed by human telomere DNA.