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Publication Abstract from PubMed

Quadruplex-duplex (QD) junctions, which represent unique structural motifs of both biological and technological significance, have been shown to constitute high-affinity binding sites for various ligands. A QD hybrid construct based on a human telomeric sequence, which harbors a duplex stem-loop in place of a short lateral loop, is structurally characterized by NMR. It folds into two major species with a (3+1) hybrid and a chair-type (2+2) antiparallel quadruplex domain coexisting in a K(+) buffer solution. The antiparallel species is stabilized by an unusual capping structure involving a thymine and protonated adenine base AH(+) of the lateral loop facing the hairpin duplex to form a T.AH(+).G.C quartet with the interfacial G.C base pair at neutral pH. Addition and binding of Phen-DC(3) to the QD hybrid mixture by its partial intercalation at corresponding QD junctions leads to a topological transition with exclusive formation of the (3+1) hybrid fold. In agreement with the available experimental data, such an unprecedented discrimination of QD junctions by a ligand can be rationalized following an induced fit mechanism.

Structural Differences at Quadruplex-Duplex Interfaces Enable Ligand-Induced Topological Transitions.,Vianney YM, Dierks D, Weisz K Adv Sci (Weinh). 2024 Jun;11(24):e2309891. doi: 10.1002/advs.202309891. Epub 2024 , Mar 13. PMID:38477454^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.