Unique Structural Features of Interconverting Monomeric and Dimeric G-Quadruplexes Adopted by a Sequence from the Intron of the N-myc Gene

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• 作者：Marko Trajkovski ; Mateus Webba da Silva ; Janez Plavec
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：March 7, 2012
• 年：2012
• 卷：134
• 期：9
• 页码：4132-4141
• 全文大小：470K
• 年卷期：v.134,no.9(March 7, 2012)
• ISSN：1520-5126

文摘

A multidimensional heteronuclear NMR study has demonstrated that a guanine-rich DNA oligonucleotide originating from the N-myc gene folds into G-quadruplex structures in the presence of K⁺, NH₄⁺, and Na⁺ ions. A monomeric G-quadruplex formed in K⁺ ion containing solution exhibits three G-quartets and flexible propeller-type loops. The 3D structure with three single nucleotide loops represents a missing element in structures of parallel G-quadruplexes. The structural features together with the high temperature stability are suggestive of the specific biological role of G-quadruplex formation within the intron of the N-myc gene. An increase in K⁺ ion and oligonucleotide concentrations resulted in transformation of the monomeric G-quadruplex into a dimeric form. The dimeric G-quadruplex exhibits six stacked G-quartets, parallel strand orientations, and propeller-type loops. A link between the third and the fourth G-quartets consists of two adenine residues that are flipped out to facilitate consecutive stacking of six G-quartets.