文献类型： 外文期刊

作者： Xue, Qingwang ¹ ; Lv, Yanqin ¹ ; Xu, Shuling ¹ ; Zhang, Yuanfu ¹ ; Wang, Lei ¹ ; Li, Rui ¹ ; Yue, Qiaoli ¹ ; Li, Haibo ¹ ; G ¹ ;

作者机构： 1.Liaocheng Univ, Dept Chem, Liaocheng 252059, Shandong, Peoples R China

2.Shandong Acad Agr Sci, Shandong Prov Key Lab Test Technol Food Qual & Sa, Jinan 250100, Peoples R China

3.Tianjin Univ Sci & Technol, Key Lab Food Nutr & Safety, Minist Educ China, Tianjin 300457, Peoples R China

关键词： Fluorescence assay;Methyltransferase;Label-free;EXPA;Supramolecular ZnPPIX/G-quadruplex

期刊名称：BIOSENSORS & BIOELECTRONICS （ 影响因子：10.618； 五年影响因子：9.323 ）

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收录情况： SCI

摘要： Site-specific identification of DNA methylation and assay of MTase activity are imperative for determining specific cancer types, provide insights into the mechanism of gene repression, and develop novel drugs to treat methylation-related diseases. Herein, we developed a highly sensitive fluorescence assay of DNA methyltransferase by methylation-sensitive cleavage-based primer generation exponential isothermal amplification (PG-EXPA) coupled with supramolecular fluorescent Zinc(II)-protoporphyrin IX (ZnPPIX)/G-quadruplex. In the presence of DNA adenine methylation (Dam) MTase, the methylation-responsive sequence of hairpin probe is methylated and cleaved by the methylation-sensitive restriction endonuclease Dpn I. The cleaved hairpin probe then functions as a signal primer to initiate the exponential isothermal amplification reaction (EXPAR) by hybridizing with a unimolecular DNA containing three functional domains as the amplification template, producing a large number of G-quadruplex nanostructures by utilizing polymerases and nicking enzymes as mechanical activators. The G-quadruplex nanostructures act as host for ZnPPIX that lead to supramolecular complexes ZnPPIX/G-quadruplex, which provides optical labels for amplified fluorescence detection of Dam MTase. While in the absence of Dam MTase, neither methylation/cleavage nor PG-EXPA reaction can be initiated and no fluorescence signal is observed. The proposed method exhibits a wide dynamic range from 0.0002 to 20 U/mL and an extremely low detection limit of 8.6 x 10(-5) U/mL, which is superior to most conventional approaches for the MTase assay. Owing to the specific site recognition of MTase toward its substrate, the proposed sensing system was able to readily discriminate Dam MTase from other MTase such as M.SssI and even detect the target in a complex biological matrix. Furthermore, the application of the proposed sensing strategy for screening Dam MTase inhibitors was also demonstrated with satisfactory results. This novel method not only provides a promising platform for monitoring activity and inhibition of DNA MTases, but also shows great potentials in biological process researches, drugs discovery and clinical diagnostics. (C) 2014 Elsevier B.V. All rights reserved.