| Title | Heterologous expression and enzymatic characterization of γ-glutamyltranspeptidase from Bacillus amyloliquefaciens |
|---|---|
| Author | Jung-Min Lee1, Jaejung Lee1,2, Gyeong-Hwa Nam1, Byung-Sam Son1, Myoung-Uoon Jang1, So-Won Lee2, Byung-Serk Hurh2, and Tae-Jip Kim1* |
| Address | 1Division of Animal, Horticultural and Food Sciences, Graduate School of Chungbuk National University, Cheongju 28644, Republic of Korea, 2Sempio Fermentation Research Center, Sempio Foods Company, Cheongju 28156, Republic of Korea |
| Bibliography | Journal of Microbiology, 55(2),147-152, 2017, |
| DOI | 10.1007/s12275-017-6638-6 |
| Key Words | γ-glutamyltranpeptidase, Bacillus amyloliquefaciens, heterologous expression, enzymatic characterization |
| Abstract | γ-Glutamyltranspeptidase (GGT) catalyzes the cleavage of γ- glutamyl compounds and the transfer of γ-glutamyl moiety to water or to amino acid/peptide acceptors. GGT can be utilized for the generation of γ-glutamyl peptides or glutamic acid, which are used as food taste enhancers. In the present study, Bacillus amyloliquefaciens SMB469 with high GGT activity was isolated from Doenjang, a traditional fermented soy food of Korea. The gene encoding GGT from B. amyloliquefaciens SMB469 (BaGGT469) was cloned from the isolate, and heterologously expressed in E. coli and B. subtilis. For comparison, three additional GGT genes were cloned from B. subtilis 168, B. licheniformis DSM 13, and B. amyloliquefaciens FZB42. The BaGGT469 protein was composed of 591 amino acids. The final protein comprises two separate polypeptide chains of 45.7 and 19.7 kDa, generated via autocatalytic cleavage. The specific activity of BaGGT469 was determined to be 17.8 U/mg with γ-L-glutamyl-p-nitroanilide as the substrate and diglycine as the acceptor. GGTs from B. amyloliquefaciens showed 1.4- and 1.7-fold higher transpeptidase activities than those from B. subtilis and B. licheniformis, respectively. Especially, recombinant B. subtilis expressing BaGGT469 demonstrated 11- and 23-fold higher GGT activity than recombinant E. coli and the native B. amyloliquefaciens, respectively, did. These results suggest that BaGGT469 can be utilized for the enzymatic production of various γ- glutamyl compounds. |