Thioflavin T as an efficient inducer and selective fluorescent sensor for the human telomeric G-quadruplex DNA

Area of Science:

• Biochemistry
• Molecular Biology
• Chemical Biology

Background:

• G-quadruplexes are non-canonical DNA structures found in telomeres and gene promoters, implicated in various cellular processes.
• Developing specific sensors for G-quadruplexes is crucial for understanding their biological roles and for therapeutic applications.

Purpose of the Study:

• To investigate Thioflavin T (ThT) as a dual-action molecule for inducing and sensing G-quadruplex DNA.
• To evaluate the specificity of ThT for human telomeric G-quadruplexes over other DNA forms.

Main Methods:

• Utilized Thioflavin T (ThT), a water-soluble fluorogenic dye, to interact with 22AG human telomeric DNA.
• Monitored fluorescence emission changes upon ThT binding and G-quadruplex formation under varying salt and buffer conditions.
• Investigated structural transitions of G-quadruplexes using potassium ion (K+) induction and analyzed thermal stabilization (ΔT(m)) by ThT.

Main Results:

• ThT exclusively induced G-quadruplex folding in 22AG DNA, exhibiting a significant fluorescence light-up with up to 2100-fold emission enhancement.
• Demonstrated a switch from parallel to antiparallel G-quadruplex structures upon K+ addition, with ThT stabilizing the antiparallel form.
• ThT showed high specificity for G-quadruplexes compared to single/double-stranded DNA, with less than 250-fold enhancement for non-quadruplex forms.

Conclusions:

• Thioflavin T serves as a novel and effective inducer and fluorescent sensor for human telomeric G-quadruplexes.
• The findings support the development of ThT-based dyes for selective telomeric DNA detection in diagnostics and therapeutics.
• This study highlights the potential of ThT for ion-sensing applications and understanding G-quadruplex structural dynamics.