Cloning of Transglutaminase Gene from Streptomyces platensis YK-2 and Its High Expression in Streptomyces Strains

The microbial transglutaminase (TGase) gene, stgA, was cloned from Streptomyces platensis YK-2, which was newly isolated from a forest soil sample collected in Daegu, Korea. The gene was expressed in several Streptomyces strains including the original strain as the host. The stgA consisted of an open reading frame of 1,257 bp encoding a putative signal peptide of 29 amino acids, a pro-domain of 57 amino acids, and a mature TGase of 332 amino acids, and also had the putative active site of TGase, YGCVG. For expression of the stgA gene, a high expression vector was constructed via the insertion of the entire stgA gene including its putative ribosomal binding site into pSET152ET, located immediately downstream of a strong constitutive ermE* promoter, and was introduced into several Streptomyces strains. The successful high expression and secretion of the correct StgA from streptomycetes were confirmed by electrophoretic sodium dodecyl sulfate polyacrylamide gel electrophoresis and N-terminal amino acid analysis.