A bacterial DNA quadruplex with exceptional K+ selectivity and unique structural polymorphism
A bacterial DNA quadruplex with exceptional K+ selectivity and unique structural polymorphism
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DOI：
10.1039/c4sc00440j
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发表时间：
2014-01-01
期刊：
影响因子：
8.4
通讯作者：
Hartig, Joerg S.
中科院分区：
文献类型：
--
作者：
Rehm, Charlotte;Holder, Isabelle T.;Hartig, Joerg S.
富含G的序列d[(G(4)CT)(3)G(4)]是最近发现的与梅毒螺旋体抗原变异相关的潜在四链形成序列。我们发现这个基序在真细菌基因组中丰富。结合CD光谱、EPR光谱、分析超速离心法和EMSA，我们证明了d[(G(4)CT)(3)G(4)]在迄今研究的许多G-四链形成序列中显示出独特的特征。据我们所知，d[(G(4)CT)(3)G(4)]对K+具有前所未有的选择性，即使高浓度的Na+也不能诱导明显的G-四链体形成。随着K+浓度的增加，从反平行的单分子结构到四聚体的平行构象发生了显著的连续和完整的转变。此外，我们还考察了阳离子选择性、四链环组成和长度以及G链长度对四链转化率的影响。
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.