Selective recognition of oncogene promoter G-quadruplexes by Mg2+.
Mg(2+) is one of the most important cations in cells, affecting the structures and functions of the proteins and nucleic acids. It should be noted that Mg(2+) is indispensable in DNA transcription, where G-quadruplex is believed to be actively involved. Therefore, it is important to investigate the influence of Mg(2+) on G-quadruplex. Here we studied the effect of Mg(2+) on G-quadruplex DNA with CD, FRET, EMSA, and PCR-stop assay. We found that various G-quadruplexes could be differentiated through simultaneous addition of both K(+) and Mg(2+), which could be used for selective identification of G-quadruplexes in promoter oncogene but not in telomere. Mg(2+) at physiological relevant concentration not only greatly enhanced the thermostability of oncogene G-quadruplexes but also efficiently protected them from unfolding by their complementary strands, which revealed the great impact of Mg(2+) on the equilibrium between promoter G-quadruplex and duplex DNA. The PCR-stop assay further confirmed that Mg(2+) could affect gene transcription by stabilizing promoter G-quadruplex. The above studies were carried out for various G-quadruplexes of varying sequences in promoter oncogenes and telomeric region. Our results suggest that Mg(2+) may be a key regulator for G-quadruplexes of oncogene promoter, which can subsequently affect the expression of related genes.
Yan
Yi-Yong
YY
School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, PR China.
Lin
Jing
J
Ou
Tian-Miao
TM
Tan
Jia-Heng
JH
Li
Ding
D
Gu
Lian-Quan
LQ
Huang
Zhi-Shu
ZS
D001483:Base Sequence; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D031541:Fluorescence Resonance Energy Transfer; D054856:G-Quadruplexes; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008274:Magnesium / Q000378:metabolism* / Q000494:pharmacology; D009857:Oncogenes; D011401:Promoter Regions, Genetic
D004247:DNA; D008274:Magnesium