Department of Biochemistry and National Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093, P. R. China.
Anal Chem. 2010 Jan 1;82(1):229-33. doi: 10.1021/ac902198v.
DNA methylation, catalyzed by methylases, plays a critical role in many biological processes, and methylases have been regarded as promising targets for antimicrobial drugs. In this paper, we propose a simple and sensitive colorimetric assay method to detect the activity of methylases so as to monitor DNA methylation using DNA-modified gold nanoparticles (AuNPs) coupled with enzyme-linkage reactions. The duplex DNA molecules modified on the surface of AuNPs are first methylated by DNA adenine methylation (Dam) methyltransferase (MTase) and then cut by methylation-sensitive restriction endonuclease Dpn I. Removal of duplex from the AuNP surfaces by the methylation/cleavage process will destabilize the nanoparticles, resulting in aggregation of AuNPs and a red-to-blue color change. Consequently, the enzyme activity of Dam MTase can be assayed and DNA methylation can be detected. Furthermore, this study may provide a sensitive platform to screen inhibitors for Dam MTase.
DNA 甲基化由甲基转移酶催化，在许多生物过程中发挥着关键作用，甲基转移酶已被视为有前途的抗菌药物靶点。在本文中，我们提出了一种简单灵敏的比色分析方法来检测甲基转移酶的活性，从而使用 DNA 修饰的金纳米粒子（AuNPs）结合酶联反应来监测 DNA 甲基化。首先，用 DNA 腺嘌呤甲基化（Dam）甲基转移酶（MTase）对 AuNPs 表面修饰的双链 DNA 分子进行甲基化，然后用甲基化敏感的限制性内切酶 Dpn I 进行切割。通过甲基化/切割过程从 AuNP 表面去除双链会使纳米粒子不稳定，导致 AuNP 聚集和颜色从红色变为蓝色。因此，可以测定 Dam MTase 的酶活性并检测 DNA 甲基化。此外，该研究可能为筛选 Dam MTase 的抑制剂提供一个敏感的平台。
