Abstract: Mycobacterium tuberculosis, the pathogen of tuberculosis, is one of the deadliest pathogens of infectious diseases, however the epidemic situation of COVID-19 in 2019 dealt a heavy blow to the prevention and treatment of tuberculosis. Therefore, the in-depth study of Mycobacterium tuberculosis is of great significance. The study of genomics shows that DNA-3-methyladenine glycosylase I TagA from Mycobacterium tuberculosis (MtbTagA) recognizes and removes damaged alkylated bases in order to maintain normal replication, transcription and translation of the genome, whereas the type of binding substrate, catalytic mechanism and structural basis are not clear. In this study, MtbTagA was heterologous expressed in E. coli, and the high purity protein was obtained by nickel medium affinity chromatography, anion exchange chromatography and gel filtration chromatography. Dynamic light scattering (DLS) experiments showed that MtbTagA protein was distributed as a monomer in solution and could bind to substrate 3-methyladenine (3MA) and hypoxanthine (Hx) and change its aggregation state. The flake crystals were selected and optimized by further crystallization, and the diffraction data with a resolution of 7 Å were obtained. It provides a reference for further study on the biochemical properties and structure of DNA glycosylase protein.
Key words: DNA glycosylase; TagA; Mycobacterium tuberculosis; dynamic light scattering; crystallization
（Acta Laser Biology Sinica, 2021, 30(4): 325-332）