A bacterial DNA quadruplex with exceptional K + selectivity and unique structural polymorphism

The G-rich sequence d[(G 4 CT) 3 G 4 ] was recently identified as a potential quadruplex-forming sequence associated with loci involved in antigenic variation in the human pathogen Treponema pallidum . We found this motif to be enriched in eubacterial genomes. Employing a combination of CD spectrosc...

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Published in:Chemical science (Cambridge) 2014, Vol.5 (7), p.2809-2818
Main Authors: Rehm, Charlotte, Holder, Isabelle T., Groß, Andreas, Wojciechowski, Filip, Urban, Maximilian, Sinn, Malte, Drescher, Malte, Hartig, Jörg S.
Format: Article
Language:English
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Summary:The G-rich sequence d[(G 4 CT) 3 G 4 ] was recently identified as a potential quadruplex-forming sequence associated with loci involved in antigenic variation in the human pathogen Treponema pallidum . We found this motif to be enriched in eubacterial genomes. Employing a combination of CD spectroscopy, EPR spectroscopy, analytical ultracentrifugation, and EMSA, we demonstrate that d[(G 4 CT) 3 G 4 ] displays unique features among the many G-quadruplex-forming sequences studied so far. To our knowledge d[(G 4 CT) 3 G 4 ] shows a so far unprecedented selectivity for K + with even high concentrations of Na + unable to induce pronounced G-quadruplex formation. A remarkable continuous and complete transition from an anti-parallel, monomolecular structure into a tetrameric, parallel conformation is observed upon increasing K + -concentrations. Furthermore we investigate the effects of cation selectivity, quadruplex loop composition and length as well as G-tract length on quadruplex conversion.
ISSN:2041-6520
2041-6539
DOI:10.1039/C4SC00440J