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Publication Abstract from PubMed

A four-repeat human telomere DNA sequence without the 3'-end guanine, d[TAGGG(TTAGGG)2 TTAGG] (htel1-DeltaG23) has been found to adopt two distinct two G-quartet antiparallel basket-type G-quadruplexes, TD and KDH(+) in presence of KCl. NMR, CD, and UV spectroscopy have demonstrated that topology of KDH(+) form is distinctive with unique protonated T18A20(+) G5 base triple and other capping structural elements that provide novel insight into structural polymorphism and heterogeneity of G-quadruplexes in general. Specific stacking interactions amongst two G-quartets flanking base triples and base pairs in TD and KDH(+) forms are reflected in 10 K higher thermal stability of KDH(+) . Populations of TD and KDH(+) forms are controlled by pH. The (de)protonation of A20 is the key for pH driven structural transformation of htel1-DeltaG23. Reversibility offers possibilities for its utilization as a conformational switch within different compartments of living cell enabling specific ligand and protein interactions.

Reversible pH Switch of Two-Quartet G-Quadruplexes Formed by Human Telomere.,Galer P, Wang B, Sket P, Plavec J Angew Chem Int Ed Engl. 2016 Feb 5;55(6):1993-7. doi: 10.1002/anie.201507569., Epub 2016 Jan 6. PMID:26836334^[1]

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