Terminal deoxynucleotidyl transferase induced activators to unlock the trans-cleavage of CRISPR/Cpf 1 (TdT-IU- CRISPR/Cpf 1): An ultrasensitive biosensor for Dam MTase activity detection

DNA adenine methylation methyltransferase (Dam MTase) plays an important role in gene expression and cell development, and involves in some development of tumors. There are many methods to detect Dam MTase activity, yet they have some shortcomings such as high cost, limited detection limit and complicated operation. Here, a new fast and simple multiple amplification strategy based on terminal deoxynucleotidyl transferase induced activators to unlock the collateral cleavage activities (trans-cleavage) of CRISPR/Cpf 1 (TdT-IU-CRISPR/Cpf 1) was firstly established. Based on this, a new fluorescent biosensor for Dam MTase activity detection was proposed. Importantly, the proposed biosensor does not require strict control over the temperature changes, and has ultrasensitive detection with limit of detection as low as 1.26 x 10(-3) U/mL. Moreover, the novel biosensor can not only be applied for screening the inhibitors for Dam MTase activity, but also can detect its activity in complex biological samples. The newly established multiple amplification strategy TdT-IU-CRISPR/Cpf 1 and the proposed biosensor for Dam MTase activity will be of great significance in biomedical testing and clinical diagnostics.