Molecular insights into the mechanism of substrate recognition of Streptomyces transglutaminases

Abstract

The microbial TGase from Streptomyces mobaraensis has used in various food industries. However, the detailed substrate specificities of TGases from the Streptomyces species toward the natural peptides remains to be unclear. In this study, we conducted the comparison of two different TGases from Streptomyces mobaranensis (SMTG) and Streptomyces cinnamoneus (SCTG). To clarify the region associated with the characteristics of enzymes, we constructed a chimeric enzyme of CM, of which is consisted of N-terminal half of SCTG and C-terminal half of SMTG. To reveal the differences in the substrate specificity between SCTG and SMTG toward natural peptides, we investigated the time dependence of TGase activity on the productivity of cross-linking peptide with tryptic casein and lysine by using LC-MS. We identified two peptides of “VLPVPQK” and “AVPYPQR” as substrates for both of the TGases.