Abstract:[Background] Transglutaminase (TGase) is an enzyme that catalyzes the acyl transfer reaction, which can catalyze cross-linking reactions between or within various protein molecules, and has important potential value in the food, cosmetics, medicine and other fields. [Objective] Molecular engineering and site-directed mutagenesis were carried out by cloning glutamyl transferase from Streptoverticillium ladakanum B1 to obtain efficient heterologous expression in E. coli. [Methods] The gene of pro and TG from Streptoverticillium ladakanum were cloned into pET-22b to generate co-expression and fusion expression, respectively. Based on these two expression patterns, the first four amino acids of the mature TGase N-terminal were modified by site-directed mutagenesis to detect the effect of different expression patterns and mutation on enzyme activity. [Results] When co-expression of the pro-peptide with TGase, the active form of TGase can be obtained directly, and the specific activity reaches 37.71 U/mg. Based on the fusion expression, the first three amino acid DSD of the N-terminal of TGase were mutated to AAA, and the specific enzyme activity reached 14.04 U/mg, which was 14.05% higher than the original expression pattern. [Conclusion] The co-expression of pro-peptide with TGase can directly produce the active form of TGase. For the fusion expression pattern, the mutation of the appropriate site is beneficial to increase the TGase activity.
