Kinetics and mechanism of G-quadruplex formation and conformational switch in a G-quadruplex of PS2.M induced by Pb2+

DNA sequences with guanine repeats can form G-quartets that adopt G-quadruplex structures in the presence of specific metal ions. Using circular dichroism (CD) and ultraviolet-visible (UV–Vis) spectroscopy, we determined the spectral characteristics and the overall conformation of a G-quadruplex of...

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Main Authors:	Liu, Wei, Zhu, Hong, Zheng, Bin, Cheng, Sheng, Fu, Yan, Li, Wei, Lau, Tai-Chu, Liang, Haojun
Format:	Online
Language:	English
Published:	Oxford University Press 2012
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3351173/

id	pubmed-3351173
recordtype	oai_dc
spelling	pubmed-33511732012-05-14 Kinetics and mechanism of G-quadruplex formation and conformational switch in a G-quadruplex of PS2.M induced by Pb2+ Liu, Wei Zhu, Hong Zheng, Bin Cheng, Sheng Fu, Yan Li, Wei Lau, Tai-Chu Liang, Haojun Structural Biology DNA sequences with guanine repeats can form G-quartets that adopt G-quadruplex structures in the presence of specific metal ions. Using circular dichroism (CD) and ultraviolet-visible (UV–Vis) spectroscopy, we determined the spectral characteristics and the overall conformation of a G-quadruplex of PS2.M with an oligonucleotide sequence, d(GTG3TAG3CG3TTG2). UV-melting curves demonstrate that the Pb2+-induced G-quadruplex formed unimolecularly and the highest melting temperature (Tm) is 72°C. The analysis of the UV titration results reveals that the binding stoichiometry of Pb2+ ions to PS2.M is two, suggesting that the Pb2+ ions coordinate between adjacent G-quartets. Binding of ions to G-rich DNA is a complex multiple-pathway process, which is strongly affected by the type of the cations. Kinetic studies suggest that the Pb2+-induced folding of PS2.M to G-quadruplex probably proceeds through a three-step pathway involving two intermediates. Structural transition occurs after adding Pb(NO3)2 to the Na+- or K+-induced G-quadruplexes, which may be attributed to the replacement of Na+ or K+ by Pb2+ ions and the generation of a more compact Pb2+–PS2.M structure. Comparison of the relaxation times shows that the Na+→Pb2+ exchange is more facile than the K+→Pb2+ exchange process, and the mechanisms for these processes are proposed. Oxford University Press 2012-05 2012-01-11 /pmc/articles/PMC3351173/ /pubmed/22241774 http://dx.doi.org/10.1093/nar/gkr1310 Text en © The Author(s) 2012. Published by Oxford University Press. http://creativecommons.org/licenses/by-nc/3.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Liu, Wei Zhu, Hong Zheng, Bin Cheng, Sheng Fu, Yan Li, Wei Lau, Tai-Chu Liang, Haojun
spellingShingle	Liu, Wei Zhu, Hong Zheng, Bin Cheng, Sheng Fu, Yan Li, Wei Lau, Tai-Chu Liang, Haojun Kinetics and mechanism of G-quadruplex formation and conformational switch in a G-quadruplex of PS2.M induced by Pb2+
author_facet	Liu, Wei Zhu, Hong Zheng, Bin Cheng, Sheng Fu, Yan Li, Wei Lau, Tai-Chu Liang, Haojun
author_sort	Liu, Wei
title	Kinetics and mechanism of G-quadruplex formation and conformational switch in a G-quadruplex of PS2.M induced by Pb2+
title_short	Kinetics and mechanism of G-quadruplex formation and conformational switch in a G-quadruplex of PS2.M induced by Pb2+
title_full	Kinetics and mechanism of G-quadruplex formation and conformational switch in a G-quadruplex of PS2.M induced by Pb2+
title_fullStr	Kinetics and mechanism of G-quadruplex formation and conformational switch in a G-quadruplex of PS2.M induced by Pb2+
title_full_unstemmed	Kinetics and mechanism of G-quadruplex formation and conformational switch in a G-quadruplex of PS2.M induced by Pb2+
title_sort	kinetics and mechanism of g-quadruplex formation and conformational switch in a g-quadruplex of ps2.m induced by pb2+
description	DNA sequences with guanine repeats can form G-quartets that adopt G-quadruplex structures in the presence of specific metal ions. Using circular dichroism (CD) and ultraviolet-visible (UV–Vis) spectroscopy, we determined the spectral characteristics and the overall conformation of a G-quadruplex of PS2.M with an oligonucleotide sequence, d(GTG3TAG3CG3TTG2). UV-melting curves demonstrate that the Pb2+-induced G-quadruplex formed unimolecularly and the highest melting temperature (Tm) is 72°C. The analysis of the UV titration results reveals that the binding stoichiometry of Pb2+ ions to PS2.M is two, suggesting that the Pb2+ ions coordinate between adjacent G-quartets. Binding of ions to G-rich DNA is a complex multiple-pathway process, which is strongly affected by the type of the cations. Kinetic studies suggest that the Pb2+-induced folding of PS2.M to G-quadruplex probably proceeds through a three-step pathway involving two intermediates. Structural transition occurs after adding Pb(NO3)2 to the Na+- or K+-induced G-quadruplexes, which may be attributed to the replacement of Na+ or K+ by Pb2+ ions and the generation of a more compact Pb2+–PS2.M structure. Comparison of the relaxation times shows that the Na+→Pb2+ exchange is more facile than the K+→Pb2+ exchange process, and the mechanisms for these processes are proposed.
publisher	Oxford University Press
publishDate	2012
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3351173/
_version_	1611529288751775744

Kinetics and mechanism of G-quadruplex formation and conformational switch in a G-quadruplex of PS2.M induced by Pb2+

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