Download MendeleyIndoloquinoline Ligands Favor Intercalation at Quadruplex-Duplex Interfaces.
Vianney, Y.M., Weisz, K.(2022) Chemistry 28: e202103718-e202103718
- PubMed: 34905232
- DOI: https://doi.org/10.1002/chem.202103718
- Primary Citation of Related Structures:
7PNE, 7PNG - PubMed Abstract:
Quadruplex-duplex (Q-D) junctions are increasingly considered promising targets for medicinal and technological applications. Here, a Q-D hybrid with a hairpin-type snapback loop coaxially stacked onto the quadruplex 3'-outer tetrad was designed and employed as a target structure for the indoloquinoline ligand SYUIQ-5. NMR spectral analysis demonstrated high-affinity binding of the ligand at the quadruplex-duplex interface with association constants determined by isothermal titration calorimetry of about 10 7 M -1 and large exothermicities ΔH° of -14 kcal/mol in a 120 mM K + buffer at 40 °C. Determination of the ligand-bound hybrid structure revealed intercalation of SYUIQ-5 between 3'-outer tetrad and the neighboring CG base pair, maximizing π-π stacking as well as electrostatic interactions with guanine carbonyl groups in close vicinity to the positively charged protonated quinoline nitrogen of the tetracyclic indoloquinoline. Exhibiting considerable flexibility, the SYUIQ-5 sidechain resides in the duplex minor groove. Based on comparative binding studies with the non-substituted N5-methylated indoloquinoline cryptolepine, the sidechain is suggested to confer additional affinity and to fix the alignment of the intercalated indoloquinoline aromatic core. However, selectivity for the Q-D junction mostly relies on the geometry and charge distribution of the indoloquinoline ring system. The presented results are expected to provide valuable guidelines for the design of ligands specifically targeting Q-D interfaces.
Organizational Affiliation:
Institute of Biochemistry, Universität Greifswald, Felix-Hausdorff-Str. 4, 17489, Greifswald, Germany.
