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Suzuki M, Date M, Kashiwagi T, Suzuki E, Yokoyama K. Rational design of a disulfide bridge increases the thermostability of microbial transglutaminase. Appl Microbiol Biotechnol 2022; 106:4553-4562. [PMID: 35729274 DOI: 10.1007/s00253-022-12024-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Revised: 06/06/2022] [Accepted: 06/09/2022] [Indexed: 11/02/2022]
Abstract
Microbial transglutaminase (MTG) has numerous industrial applications in the food and pharmaceutical sectors. Unfortunately, the thermostability of MTG is too low to tolerate the desired conditions used in many of these commercial processes. In a previous study, we used protein engineering to improve the thermostability of MTG. Specifically, we generated a T7C/E58C mutant of MTG from Streptomyces mobaraensis that displayed enhanced resistance to thermal inactivation. In this study, a rational structure-based approach was adopted to introduce a disulfide bridge to further increase the thermostability of MTG. In all, four new mutants, each containing a novel disulfide bond, were engineered. Of these four mutants, D3C/G283C showed the most promising thermostability with a significantly higher ∆T50 (defined as the temperature of incubation at which 50% of the initial activity remains) of + 9 °C by comparison to wild-type MTG. Indeed, D3C/G283C combined enhanced thermostability with a 2.1-fold increased half-life at 65 °C compared with the wild-type enzyme. By structure-based rational design, we were able to create an MTG variant which might be useful for expanding the scope of application in food. KEY POINTS: • Microbial transglutaminase (MTG) is an enzyme used in many food applications • The applicability of MTG to various industrial processes other than the food sector is being investigated • Improvement of thermostability was confirmed for the disulfide bridge mutant D3C/G283C.
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Affiliation(s)
- Mototaka Suzuki
- Institute for Innovation, Ajinomoto Co., Inc., 1-1, Suzuki-cho, Kawasaki-shi, Kanagawa, 210-8681, Japan
| | - Masayo Date
- Institute for Innovation, Ajinomoto Co., Inc., 1-1, Suzuki-cho, Kawasaki-shi, Kanagawa, 210-8681, Japan
| | - Tatsuki Kashiwagi
- Institute for Innovation, Ajinomoto Co., Inc., 1-1, Suzuki-cho, Kawasaki-shi, Kanagawa, 210-8681, Japan
| | - Eiichiro Suzuki
- Institute for Innovation, Ajinomoto Co., Inc., 1-1, Suzuki-cho, Kawasaki-shi, Kanagawa, 210-8681, Japan.,Kihara Memorial Yokohama Foundation for the Advancement of Life Sciences Yokohama, Bio Industry Center, 1-6 Suehiro-cho, Tsurumi-ku, Yokohama, 230-0045, Japan
| | - Keiichi Yokoyama
- Institute for Innovation, Ajinomoto Co., Inc., 1-1, Suzuki-cho, Kawasaki-shi, Kanagawa, 210-8681, Japan. .,R&B Planning Department, Ajinomoto Co., Inc, Tokyo, 104-8315, Japan.
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Effect of introducing a disulfide bridge on the thermostability of microbial transglutaminase from Streptomyces mobaraensis. Appl Microbiol Biotechnol 2021; 105:2737-2745. [PMID: 33738551 DOI: 10.1007/s00253-021-11200-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 02/11/2021] [Accepted: 02/24/2021] [Indexed: 10/21/2022]
Abstract
Microbial transglutaminase (MTG) has been used extensively in academic research and the food industry through cross-linking or posttranslational modification of proteins. In our previous paper, the activity-increased MTG mutants were obtained by means of rational mutagenesis and random mutagenesis coupled with the newly developed screening system. In addition, the improvement of heat resistance of MTG is needed to expand further its industrial applications. Here, a structure-based rational enzyme engineering approach was applied to improve the thermostability of MTG by introducing an artificial disulfide bridge. As a result of narrowing down candidates using a rational approach, we successfully engineered a disulfide bridge into the N-terminal region of MTG by substituting Thr-7 and Glu-58 with cysteine. The T7C/E58C mutant was observed to have a de novo disulfide bridge and showed an increased melting temperature (Tm value) of 4.3 °C with retained enzymatic activity. To address the benefit-gained reason, we focused on the Cβ temperature factor of the amino-acid residues that might form a disulfide bridge in MTG. Introducing the disulfide bridge had no remarkable effect on the mutant aiming to stabilize the high temperature factor. On the other hand, the mutation was effective on the relatively stable region. The introduction of a disulfide bridge may therefore be effective to stabilize further the relatively stable part. This finding is considered to be useful for the rational design of mutants aiming at heat resistance of proteins.Key Points• Microbial transglutaminase (MTG) is used as a binder in the food industry.• MTG has the potential for use in the manufacturing of various commercial materials.• Enhanced thermostability was observed for the disulfide bridge mutant, T7C/G58C.
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Goto Y, Adachi M, Muta H, So M. Salt-induced formations of partially folded intermediates and amyloid fibrils suggests a common underlying mechanism. Biophys Rev 2017; 10:493-502. [PMID: 29256120 DOI: 10.1007/s12551-017-0370-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 11/19/2017] [Indexed: 12/26/2022] Open
Abstract
Amyloid fibrils are misfolded forms of proteins and are involved in various diseases. They have been studied extensively with the aim to obtain a comprehensive understanding of protein folding and misfolding and to use this knowledge to develop therapeutic strategies against the associated diseases. Salt conditions are important factors determining the formation and stability of amyloid fibrils. In the 1990s, salt effects were studied extensively to understand the conformational stability of acid-denatured proteins, and the results of these studies revealed the role of electrostatic repulsion in forming the compact intermediate states. In this review, we compare the effects of salts on the compact intermediate states with those on the formation of amyloid fibrils under acidic conditions. The results argue that both protein folding and misfolding are driven by the same forces, although the resultant conformations are distinct because they are monomeric and multimeric reactions, respectively.
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Affiliation(s)
- Yuji Goto
- Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka, 565-0871, Japan.
| | - Masayuki Adachi
- Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka, 565-0871, Japan
| | - Hiroya Muta
- Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka, 565-0871, Japan
| | - Masatomo So
- Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka, 565-0871, Japan
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pH-dependent activation of Streptomyces hygroscopicus transglutaminase mediated by intein. Appl Environ Microbiol 2013; 80:723-9. [PMID: 24242235 DOI: 10.1128/aem.02820-13] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microbial transglutaminase (MTG) from Streptomyces is naturally secreted as a zymogen (pro-MTG), which is then activated by the removal of its N-terminal proregion by additional proteases. Inteins are protein-intervening sequences that catalyze protein splicing without cofactors. In this study, a pH-dependent Synechocystis sp. strain PCC6803 DnaB mini-intein (SDB) was introduced into pro-MTG to simplify its activation process by controlling pH. The recombinant protein (pro-SDB-MTG) was obtained, and the activation process was determined to take 24 h at pH 7 in vitro. To investigate the effect of the first residue in MTG on the activity and the cleavage time, two variants, pro-SDB-MTG(D1S) and pro-SDB-MTG(ΔD1), were expressed, and the activation time was found to be 6 h and 30 h, respectively. The enzymatic property and secondary structure of the recombinant MTG and two variants were similar to those of the wild type, indicating that the insertion of mini-intein did not affect the function of MTG. This insignificant effect was further illustrated by molecular dynamics simulations. This study revealed a controllable and effective strategy to regulate the activation process of pro-MTG mediated by a mini-intein, and it may have great potential for industrial MTG production.
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Rachel NM, Pelletier JN. Biotechnological applications of transglutaminases. Biomolecules 2013; 3:870-88. [PMID: 24970194 PMCID: PMC4030973 DOI: 10.3390/biom3040870] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 10/10/2013] [Accepted: 10/11/2013] [Indexed: 12/28/2022] Open
Abstract
In nature, transglutaminases catalyze the formation of amide bonds between proteins to form insoluble protein aggregates. This specific function has long been exploited in the food and textile industries as a protein cross-linking agent to alter the texture of meat, wool, and leather. In recent years, biotechnological applications of transglutaminases have come to light in areas ranging from material sciences to medicine. There has also been a substantial effort to further investigate the fundamentals of transglutaminases, as many of their characteristics that remain poorly understood. Those studies also work towards the goal of developing transglutaminases as more efficient catalysts. Progress in this area includes structural information and novel chemical and biological assays. Here, we review recent achievements in this area in order to illustrate the versatility of transglutaminases.
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Affiliation(s)
- Natalie M Rachel
- Chimie, Université de Montréal, 2900 Boulevard Edouard-Montpetit, Montréal, Québec, H3T 1J4, Canada.
| | - Joelle N Pelletier
- Chimie, Université de Montréal, 2900 Boulevard Edouard-Montpetit, Montréal, Québec, H3T 1J4, Canada.
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