Abnormal DNA methylation is closely related to the occurrence and development of many diseases. The determination of human DNA methyltransferase activity and the screening of its inhibitors are extreme important for the diagnosis and the treatment of methylation-related diseases in clinic. Most of the current detection methods have the disadvantages of sophisticated design, high cost and low detection limit. By combining T7 promoter-contained DNA probe as the substrate for methyltransferase with CRISPR/Cas13a sensing strategy, a novel fluorescent sensing platform is designed to achieve simple, specific, sensitive detection of bacteria DNA methyltransferase (DNA-(N-6-adenine)-methyltransferase, Dam MTase) and also human methyltransferase (DNA (cytosine-5)-methyltransferase 1, Dnmt1). A hairpin DNA probe designed for Dam MTase and a double strand DNA probe for Dnmt1 are both methylated followed by the methylation-dependent site-specific cleavage, which result a T7 promoter-contained product and a T7 promoter-free one to respectively open and close the transcription and subsequent CRISPR/Cas13a target-initiated cleavage of fluorescence-labeled reporter RNA. In virtue of the specificity of methylation-dependent cleavage of probe, the efficient transcription amplification and CRISPR/Cas13a sequence-specific sensing, this strategy exhibited remarkable specificity and sensitivity, with the limit of detection of 3.10 $\times$ 10⁻⁵ U/mL for Dam MTase. Moreover, Dnmt1 activity in MCF-7 cells was detected and the inhibition of Apt. #9 was evaluated. This strategy for methyltransferase detection is convenient and efficient for inhibitor discovery and early cancer diagnosis.

DNA甲基化异常与许多疾病的发生、发展密切相关。人DNA甲基转移酶活性的测定及其抑制剂的筛选对于临床上甲基化相关疾病的诊断和治疗具有极其重要的意义。目前的检测方法大多存在设计复杂、成本高、检测限低等缺点。通过将含有 T7 启动子的 DNA 探针作为甲基转移酶的底物与 CRISPR/Cas13a 传感策略相结合，设计了一种新型的荧光传感平台，以实现对细菌 DNA 甲基转移酶 (DNA-(N-6-adenine)-甲基转移酶，Dam MTase）和人甲基转移酶（DNA（胞嘧啶-5）-甲基转移酶 1，Dnmt1）。为 Dam MTase 设计的发夹 DNA 探针和为 Dnmt1 设计的双链 DNA 探针均被甲基化，然后进行甲基化依赖性位点特异性切割，从而产生包含 T7 启动子的产物和无 T7 启动子的产物分别打开和关闭荧光标记的报告 RNA 的转录和随后的 CRISPR/Cas13a 靶启动切割。凭借探针甲基化依赖性切割的特异性、高效的转录扩增和CRISPR/Cas13a序列特异性传感，该策略表现出显着的特异性和灵敏度，检测限为3.10 这导致含有 T7 启动子的产物和不含 T7 启动子的产物分别打开和关闭荧光标记的报告 RNA 的转录和随后的 CRISPR/Cas13a 靶标引发的切割。凭借探针甲基化依赖性切割的特异性、高效的转录扩增和CRISPR/Cas13a序列特异性传感，该策略表现出显着的特异性和灵敏度，检测限为3.10 这导致含有 T7 启动子的产物和不含 T7 启动子的产物分别打开和关闭荧光标记的报告 RNA 的转录和随后的 CRISPR/Cas13a 靶标引发的切割。凭借探针甲基化依赖性切割的特异性、高效的转录扩增和CRISPR/Cas13a序列特异性传感，该策略表现出显着的特异性和灵敏度，检测限为3.10$\times$Dam MTase 为10 ^-5 U/mL。此外，检测到 MCF-7 细胞中的 Dnmt1 活性和 Apt 的抑制作用。#9 进行了评估。这种甲基转移酶检测策略对于发现抑制剂和早期癌症诊断来说是方便有效的。