Related Experiment Video
Updated: May 22, 2026
05:32
In Vitro Chemical Mapping of G-Quadruplex DNA Structures by Bis-3-Chloropiperidines
Published on: May 12, 2023
Binding and NMR structural studies on indoloquinoline-oligonucleotide conjugates targeting duplex DNA
Andrea Eick1, Fanny Riechert-Krause, Klaus Weisz
1Institute of Biochemistry, Ernst-Moritz-Arndt University Greifswald , Felix-Hausdorff-Strasse 4, D-17487 Greifswald, Germany.
Bioconjugate Chemistry
|May 11, 2012
Summary
The study shows that 11-phenyl-indolo[3,2-b]quinoline (PIQ) stabilizes DNA triple helices, with effectiveness depending on pH and the DNA sequence at the junction. Optimal stabilization occurs with TAT triplets under acidic conditions.
Area of Science:
- Molecular Biology
- Biochemistry
- Structural Biology
Background:
- DNA triple helix formation is a key structure in genetic regulation and therapeutic applications.
- Small molecules can be designed to bind and stabilize specific DNA structures.
- Understanding ligand-DNA interactions is crucial for developing novel DNA-targeting agents.
Purpose of the Study:
- To investigate the stabilization of parallel DNA triple helices by an 11-phenyl-indolo[3,2-b]quinoline (PIQ) derivative.
- To determine the influence of pH and the 5'-triplex-duplex junction sequence on PIQ binding and stabilization.
- To elucidate the structural basis of PIQ intercalation and its interactions within the DNA triple helix.
Main Methods:
- Synthesis of PIQ-tethered oligonucleotides.
- DNA triple helix formation and melting experiments.
- Nuclear Magnetic Resonance (NMR) spectroscopy for structural analysis.
- Molecular modeling based on NMR data.
Main Results:
- PIQ effectively stabilizes parallel DNA triple helices.
- Stabilization is highly dependent on pH, with optimal performance at low pH.
- The terminal base triad at the 5'-junction significantly impacts PIQ binding affinity, favoring TAT over CGC.
- NMR studies confirmed PIQ intercalation at the junction, revealing two coexisting species and detailed interactions with DNA.
Conclusions:
- PIQ is a potent stabilizer of DNA triple helices, with binding modulated by pH and DNA sequence.
- The observed preference for TAT over CGC triplets is attributed to protonation states and charge interactions.
- Structural insights reveal PIQ's intercalation mechanism and extensive interactions within the DNA target, offering a basis for rational drug design.
Related Concept Videos
01:28Inhibitors of Bacterial DNA Synthesis
Bacterial pathogens depend on precise and efficient DNA replication to sustain infection. Two type II topoisomerases—DNA gyrase and topoisomerase IV—are critical to this process, as they resolve DNA supercoiling and unlink chromosomes during replication. Fluoroquinolones, synthetic derivatives of quinolones, exploit this mechanism by stabilizing the transient DNA–enzyme cleavage complex, preventing strand religation, and causing lethal double-strand breaks. These antibiotics are selectively...
01:03Single-Strand DNA Binding Proteins
For successful DNA replication, the unwinding of double-stranded DNA must be accompanied by stabilization and protection of the separated single strands of the DNA. This crucial task is performed by single-strand DNA-binding (SSB) proteins. They bind to the DNA in a sequence-independent manner, which means that the nitrogenous bases of the DNA need not be present in a specific order for binding of SSB proteins to it. The binding of SSB proteins straightens single-stranded DNA (ssDNA) and makes...