Molecular Cloning and Overexpression of the Transglutaminase Gene from Streptomyces mobaraensis

Transglutaminase-catalyzed reactions can be used widely to modify the functional properties of food proteins, biopharmaceuticals and in tissue engineering. Streptomyces mobaraensis is important for industrial fermentation because of its rapid, low-cost growth and easy cultivation. We cloned the transglutaminase (TGase) gene from S. mobaraensis; the gene was 1224-bp (65.22% G+C), encoding 407 amino acids. Then, expression vector pL99-T was constructed by cloning the TGase gene into plasmid pL99. pL99-T was introduced into S. mobaraensis using conjugation and protoplast transformation method, respectively. We observed TGase activity of 8.68 U/mL in the transformant SMP-12, 5.88-fold that of the original strain (1.26 U/mL); moreover, the expression of TGase protein was higher in the transformant than in the original strain. These results suggest that directed overexpression of TGase can effectively enhance the TGase activity and protein production by S. mobaraensis. This method of enhanced expression of active TGase in S. mobaraensis may be valuable for industrial applications.