Induced topological changes in DNA complexes: influence of DNA sequences and small molecule structures

Area of Science:

• Biochemistry
• Molecular Biology
• Drug Discovery

Background:

• Heterocyclic diamidines possess antiparasitic properties.
• Their precise mechanism of action, particularly concerning DNA interaction, remains largely unknown.
• Topological alterations of DNA structures are hypothesized to be involved.

Purpose of the Study:

• To develop a screening method for assessing the topological effects of heterocyclic diamidines on DNA.
• To investigate how these compounds interact with specific DNA minor groove sequences.
• To elucidate the relationship between compound structure and DNA topological changes.

Main Methods:

• Development of a polyacrylamide gel electrophoresis (PAGE)-based screening assay.
• Evaluation of topological effects on four distinct DNA minor groove target sequences (AAAAA, TTTAA, AAATT, ATATA).
• Assessment of 13 heterocyclic diamidine compounds with varying structures.

Main Results:

• Compound binding effects are sequence-dependent, with similar trends observed for intrinsically bent (AAAAA, AAATT) and straight (TTTAA, ATATA) sequences.
• All tested compounds reduced the mobility of the ATATA sequence, indicating decreased minor groove width and bending.
• Intrinsically bent sequences showed smaller mobility changes, suggesting compound-induced alterations in bending or minor groove width.

Conclusions:

• The study established a novel PAGE-based method to screen for DNA topological changes induced by heterocyclic diamidines.
• Findings demonstrate that these compounds induce sequence-specific topological alterations in DNA minor grooves.
• The results provide a foundation for understanding the antiparasitic mechanism of heterocyclic diamidines and for structure-activity relationship studies.