title: DNA methyltransferase activity assay based on visible light-activated photoelectrochemical biosensor.
abstract: DNA methylation has important roles in gene regulation and relates to some diseases, especially cancers. Because DNA methylation is catalyzed by DNA methyltransferases (MTase), it is important to detect the activity of DNA MTase. In this work, we developed a novel visible light-activated photoelectrochemical (PEC) biosensor for DNA MTase activity assay, whereby bismuth oxyiodide (BiOI) nanoflake was synthesized as photoactive electrode material, M. SssI MTase as methylation reagent and methyl binding domain protein (MBD1 protein) as methylation recognition element. After cytosine methylation event occurred at the site of 5'-CG-3', it could be probed by MBD1 protein and this protein could be combined tightly with methylated cytosine, which would lead to a decreased photocurrent due to the hindrance towards electron donor transferring to electrode surface by huge-volume protein. The decreased photocurrent was proportional to M. SssI MTase concentration from 0.1 to 50 unit/mL with the detection limit of 0.035 unit/mL (S/N=3). This detection limit was lower than that in some previous reports. This PEC biosensor showed high selectivity and good reproducibility for M. SssI MTase assay. Moreover, this method was successfully applied also to screen DNA MTase inhibitors, indicating that this PEC biosensor could be an alternative platform in anti-cancer pharmaceuticals discovery.
authors.affiliation: College of Chemistry and Materials Science, Shandong Agricultural University, Daizong Street 61, Taian, Shandong 271018, PR China.
authors.forename: Yunlei
authors.initials: Y
authors.lastname: Zhou
authors.forename: Zhenning
authors.initials: Z
authors.lastname: Xu
authors.forename: Mo
authors.initials: M
authors.lastname: Wang
authors.forename: Bing
authors.initials: B
authors.lastname: Sun
authors.forename: Huanshun
authors.initials: H
authors.lastname: Yin
authors.forename: Shiyun
authors.initials: S
authors.lastname: Ai
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D001729:Bismuth / Q000737:chemistry; D019175:DNA Methylation / Q000235:genetics*; D015254:DNA Modification Methylases / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D008027:Light; D057230:Limit of Detection
chemical_list: D015254:DNA Modification Methylases; D001729:Bismuth
keywords: BiOI; DNA methyltransferase; Methyl binding domain protein; Photoelectrochemical biosensor