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Robescu MS, Alcántara AR, Calvio C, Morelli CF, Speranza G, Ubiali D, Bavaro T. l-Theanine Goes Greener: A Highly Efficient Bioprocess Catalyzed by the Immobilized γ-Glutamyl Transferase from Bacillus subtilis. CHEMSUSCHEM 2023; 16:e202202108. [PMID: 36655933 DOI: 10.1002/cssc.202202108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 01/18/2023] [Indexed: 06/17/2023]
Abstract
l-Theanine (l-Th) was synthesized by simply mixing the reactants (l-glutamine and ethylamine in water) at 25 °C and Bacillus subtilis γ-glutamyl transferase (BsGGT) covalently immobilized on glyoxyl-agarose according to a methodology previously reported by our research group; neither buffers, nor other additives were needed. Ratio of l-glutamine (donor) to ethylamine (acceptor), pH, enzymatic units (IU), and reaction time were optimized (molar ratio of donor/acceptor=1 : 8, pH 11.6, 1 IU mL-1 , 6 h), furnishing l-Th in 93 % isolated yield (485 mg, 32.3 g L-1 ) and high purity (99 %), after a simple filtration of the immobilized biocatalyst, distillation of the volatiles (unreacted ethylamine) and direct lyophilization. Immobilized BsGGT was re-used (four reaction cycles) with 100 % activity retention. This enzymatic synthesis represents a straightforward, fast, high-yielding, and easily scalable approach to l-Th preparation, besides having a favorable green chemistry metrics.
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Affiliation(s)
- Marina S Robescu
- Department of Drug Sciences, University of Pavia, viale Taramelli 12, Pavia, Italy
| | - Andrés R Alcántara
- Department of Chemistry in Pharmaceutical Sciences, Complutense University of Madrid, Plaza de Ramon y Cajal s/n, Madrid, Spain
| | - Cinzia Calvio
- Department of Biology and Biotechnology, University of Pavia, via Ferrata 1, Pavia, Italy
| | - Carlo F Morelli
- Department of Chemistry, University of Milan, via Golgi 19, Milano, Italy
| | - Giovanna Speranza
- Department of Chemistry, University of Milan, via Golgi 19, Milano, Italy
| | - Daniela Ubiali
- Department of Drug Sciences, University of Pavia, viale Taramelli 12, Pavia, Italy
| | - Teodora Bavaro
- Department of Drug Sciences, University of Pavia, viale Taramelli 12, Pavia, Italy
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2
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Senba H, Nishikawa A, Kimura Y, Tanaka S, Matsumoto JI, Doi M, Takenaka S. Improvement in salt-tolerance of Aspergillus oryzae γ-glutamyl transpeptidase via protein chimerization with Aspergillus sydowii homolog. Enzyme Microb Technol 2023; 167:110240. [PMID: 37084614 DOI: 10.1016/j.enzmictec.2023.110240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 04/09/2023] [Accepted: 04/10/2023] [Indexed: 04/23/2023]
Abstract
γ-Glutamyl transpeptidase is one of the key enzymes involved in glutamate production during high-salt fermentation of soy sauce and miso by koji mold, Aspergillus oryzae. However, the activity of γ-glutamyl transpeptidase from A. oryzae (AOggtA) is markedly reduced in the presence of NaCl, thus classifying it as a non-salt-tolerant enzyme. In contrast, the homologous protein from the xerophilic mold, A. sydowii (ASggtA) maintains its activity under high-salt conditions. Therefore, in this study, a chimeric enzyme, ASAOggtA, was designed and engineered to improve salt-tolerance in AOggtA by swapping the N-terminal region, based on sequence and structure comparisons between salt-tolerant ASggtA and non-salt-tolerant AOggtA. The parental AOggtA and ASggtA and their chimera, ASAOggtA, were heterologously expressed in A. oryzae and purified. The chimeric enzyme inherited the superior activity and stability from each of the two parent enzymes. ASAOggtA showed > 2-fold greater tolerance than AOggtA in the presence of 18% NaCl. In addition, the chimera showed a broader range of pH stability and greater thermostability than ASggtA. AOggtA and ASAOggtA were sy over the range pH 3.0 to pH 10.5. Thermal stability was found to be in the order AOggtA (57.5 °C, t1/2 = 32.5 min) > ASAOggtA (55 °C, t1/2 = 20.5 min) > ASggtA (50 °C, t1/2 = 12.5 min). The catalytic and structural characteristics indicated that non-salt-tolerant AOggtA would not undergo irreversible structural changes in the presence of NaCl, but rather a temporary conformational change, which might result in reducing the substrate binding and catalytic activity, on the basis of kinetic properties. In addition, the chimeric enzyme showed hydrolytic activity toward L-glutamine that was as high as that of AOggtA. The newly-designed chimeric ASAOggtA might have potential applications in high-salt fermentation, such as miso and shoyu, to increase the content of the umami-flavor amino acid, L-glutamate.
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Affiliation(s)
- Hironori Senba
- Division of Agrobioscience, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan; Ozeki Corp, Gen Res Lab, 4-9 Imazu, Nishinomiya, Hyogo 6638227, Japan
| | - Arisa Nishikawa
- Division of Agrobioscience, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Yukihiro Kimura
- Division of Agrobioscience, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Shinichi Tanaka
- Marutomo Co., Ltd, 1696 Kominato, Iyo, Ehime 799-3192, Japan
| | | | - Mikiharu Doi
- Marutomo Co., Ltd, 1696 Kominato, Iyo, Ehime 799-3192, Japan
| | - Shinji Takenaka
- Division of Agrobioscience, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan.
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Robescu M, Annunziata F, Somma V, Calvio C, Morelli CF, Speranza G, Tamborini L, Ubiali D, Pinto A, Bavaro T. From Batch to Continuous Flow Bioprocessing: Use of an Immobilized γ-Glutamyl Transferase from B. subtilis for the Synthesis of Biologically Active Peptide Derivatives. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:13692-13699. [PMID: 36149987 PMCID: PMC9614966 DOI: 10.1021/acs.jafc.2c03702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
γ-Glutamyl-peptides are frequently endowed with biological activities. In this work, "kokumi peptides" such as γ-glutamyl-methionine (1) and γ-glutamyl-(S)-allyl-cysteine (2), as well as the neuroprotective γ-glutamyl-taurine (3) and the antioxidant ophthalmic acid (4), were synthesized through an enzymatic transpeptidation reaction catalyzed by the γ-glutamyl transferase from Bacillus subtilis (BsGGT) using glutamine as the γ-glutamyl donor. BsGGT was covalently immobilized on glyoxyl-agarose resulting in high protein immobilization yield and activity recovery (>95%). Compounds 1-4 were obtained in moderate yields (19-40%, 5-10 g/L) with a variable purity depending on the presence of the main byproduct (γ-glutamyl-glutamine, 0-16%). To achieve process intensification and better control of side reactions, the synthesis of 2 was moved from batch to continuous flow. The specific productivity was 1.5 times higher than that in batch synthesis (13.7 μmol/min*g), but it was not accompanied by a paralleled improvement of the impurity profile.
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Affiliation(s)
- Marina
S. Robescu
- Department
of Drug Sciences, University of Pavia, viale Taramelli 12, Pavia 27100, Italy
| | - Francesca Annunziata
- Department
of Pharmaceutical Sciences, University of
Milano, via Mangiagalli 25, Milano 20122, Italy
| | - Valeria Somma
- Department
of Chemistry, University of Milano, via Golgi 19, Milano 20122, Italy
| | - Cinzia Calvio
- Department
of Biology and Biotechnology “L. Spallanzani”, University of Pavia, via Ferrata 1, Pavia 27100, Italy
| | - Carlo F. Morelli
- Department
of Chemistry, University of Milano, via Golgi 19, Milano 20122, Italy
| | - Giovanna Speranza
- Department
of Chemistry, University of Milano, via Golgi 19, Milano 20122, Italy
| | - Lucia Tamborini
- Department
of Pharmaceutical Sciences, University of
Milano, via Mangiagalli 25, Milano 20122, Italy
| | - Daniela Ubiali
- Department
of Drug Sciences, University of Pavia, viale Taramelli 12, Pavia 27100, Italy
| | - Andrea Pinto
- Department
of Food, Environmental and Nutritional Sciences, University of Milano, via Celoria 2, Milano 20133, Italy
| | - Teodora Bavaro
- Department
of Drug Sciences, University of Pavia, viale Taramelli 12, Pavia 27100, Italy
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Sharma E, Lal MK, Gulati A, Gulati A. Heterologous expression, on-column refolding and characterization of gamma-glutamyl transpeptidase gene from Bacillus altitudinis IHB B1644: A microbial bioresource from Western Himalayas. Process Biochem 2022. [DOI: 10.1016/j.procbio.2022.02.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Cho HB, Ahn JH, Yang HG, Lee J, Park WJ, Kim YW. Effects of pH and NaCl on hydrolysis and transpeptidation activities of a salt-tolerant γ-glutamyltranspeptidase from Bacillus amyloliquefaciens S0904. Food Sci Biotechnol 2021; 30:853-860. [PMID: 34249391 DOI: 10.1007/s10068-021-00928-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/10/2021] [Accepted: 06/08/2021] [Indexed: 11/30/2022] Open
Abstract
Bacillus amyloliquefaciens S0904 was selected as a hyperproducer of a glutamine-hydrolyzing enzyme which was identified as a γ-glutamyltranspeptidase catalyzing both hydrolysis and transpeptidation of glutamyl substrates. The signal peptide-truncated recombinant enzyme (rBAGGT) showed two-fold enhanced specific activity for hydrolysis and optimum pH shift to pH 7 from pH 6 compared with the wild type. The hydrolysis activity of rBAGGT was tolerant against NaCl up to 2.5 M, whereas the transpeptidation activity decreased by NaCl. At pH 6, the addition of 1.5 M NaCl not only enhanced the hydrolysis activity but also inhibited the transpeptidation activity to be ignorable. By contrast, at pH 9 in the absence of NaCl, the alkaline pH-favored transpeptidation activity was 99% of the maximum with only 15% of the maximum hydrolysis activity. In conclusion, the hydrolysis and transpeptidation activities of the recombinant BAGGT is controllable by changing pH and whether or not to add NaCl. Supplementary Information The online version contains supplementary material available at 10.1007/s10068-021-00928-6.
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Affiliation(s)
- Hye-Bin Cho
- Department of Food and Biotechnology, Korea University, Sejong, 30019 Republic of Korea
| | - Jun-Ho Ahn
- Department of Food and Biotechnology, Korea University, Sejong, 30019 Republic of Korea
| | - Hyeon-Gyu Yang
- Department of Food and Biotechnology, Korea University, Sejong, 30019 Republic of Korea
| | - Jaeick Lee
- Department of Food and Biotechnology, Korea University, Sejong, 30019 Republic of Korea
| | - Wu-Jin Park
- R&D Center, Nongshim Co., Seoul, 07057 Republic of Korea
| | - Young-Wan Kim
- Department of Food and Biotechnology, Korea University, Sejong, 30019 Republic of Korea
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Saini M, Kashyap A, Bindal S, Saini K, Gupta R. Bacterial Gamma-Glutamyl Transpeptidase, an Emerging Biocatalyst: Insights Into Structure-Function Relationship and Its Biotechnological Applications. Front Microbiol 2021; 12:641251. [PMID: 33897647 PMCID: PMC8062742 DOI: 10.3389/fmicb.2021.641251] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 02/15/2021] [Indexed: 12/16/2022] Open
Abstract
Gamma-glutamyl transpeptidase (GGT) enzyme is ubiquitously present in all life forms and plays a variety of roles in diverse organisms. Higher eukaryotes mainly utilize GGT for glutathione degradation, and mammalian GGTs have implications in many physiological disorders also. GGTs from unicellular prokaryotes serve different physiological functions in Gram-positive and Gram-negative bacteria. In the present review, the physiological significance of bacterial GGTs has been discussed categorizing GGTs from Gram-negative bacteria like Escherichia coli as glutathione degraders and from pathogenic species like Helicobacter pylori as virulence factors. Gram-positive bacilli, however, are considered separately as poly-γ-glutamic acid (PGA) degraders. The structure-function relationship of the GGT is also discussed mainly focusing on the crystallization of bacterial GGTs along with functional characterization of conserved regions by site-directed mutagenesis that unravels molecular aspects of autoprocessing and catalysis. Only a few crystal structures have been deciphered so far. Further, different reports on heterologous expression of bacterial GGTs in E. coli and Bacillus subtilis as hosts have been presented in a table pointing toward the lack of fermentation studies for large-scale production. Physicochemical properties of bacterial GGTs have also been described, followed by a detailed discussion on various applications of bacterial GGTs in different biotechnological sectors. This review emphasizes the potential of bacterial GGTs as an industrial biocatalyst relevant to the current switch toward green chemistry.
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Affiliation(s)
| | | | | | | | - Rani Gupta
- Department of Microbiology, University of Delhi South Campus, New Delhi, India
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Li Z, Zhu R, Liu Y, Li J, Gao H, Hu N. γ-Glutamyltranspeptidase from Bacillus amyloliquefaciens: transpeptidation activity enhancement and L-theanine production. Enzyme Microb Technol 2020; 140:109644. [PMID: 32912696 DOI: 10.1016/j.enzmictec.2020.109644] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 08/01/2020] [Accepted: 08/04/2020] [Indexed: 12/11/2022]
Abstract
L-theanine, a unique amino acid in green tea with health benefits, can be enzymatically synthesized by γ-glutamyltranspeptidase (γ-GT; EC 2.3.2.2). Here, a salt-tolerant γ-glutamyltranspeptidase from a marine bacterium Bacillus amyloliquefaciens was expressed in Escherichia. coli BL21 (DE3) and was shown to be optimally active at 55 °C, pH 8.5 and alkali stable. A mutant, with higher transpeptidation activity, was obtained following two rounds of directed evolution using error-prone PCR and site-saturation mutagenesis. The mutation increased the ratio of transpeptidation to hydrolysis from 1.6 to 35.6. Additionally, Kinetic analysis exhibited 17.5% decrease of Km, 13.0-fold increase of Kcat, and 16.3-fold increase of Kcat/Km in mutant V319A/S437 G versus the wild-type. The 3-D modelling analysis revealed a tighter binding pocket in mutant V319A/S437 G. The frequency of hydrogen bond between donor substrate and two residues in the catalytic pocket (Gly437 and Thr375) was enhanced, which stabilized the ligand binding and thus improved the catalytic efficiency. The optimal conditions for the biocatalytic synthesis were determined as pH 10.0, 20 μg mL-1BaGT, 200 mM L-glutamine, 2 M ethylamine, and a reaction time of 5 h. The V319A/S437 G mutant was shown to increase the percentage yield of L-theanine from 58% to 83%. These results indicate the great potential of V319A/S437 G in L-theanine production after further study.
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Affiliation(s)
- Zelong Li
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, China.
| | - Runtao Zhu
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, China.
| | - Yongqi Liu
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, China.
| | - Jiaqi Li
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, China.
| | - Haofeng Gao
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, China.
| | - Nan Hu
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, China.
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Mutational Analysis of a Highly Conserved PLSSMXP Sequence in the Small Subunit of Bacillus licheniformis γ-Glutamyltranspeptidase. Biomolecules 2019; 9:biom9090508. [PMID: 31546955 PMCID: PMC6769717 DOI: 10.3390/biom9090508] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 09/18/2019] [Accepted: 09/19/2019] [Indexed: 01/13/2023] Open
Abstract
A highly conserved 458PLSSMXP464 sequence in the small subunit (S-subunit) of an industrially important Bacillus licheniformis γ-glutamyltranspeptidase (BlGGT) was identified by sequence alignment. Molecular structures of the precursor mimic and the mature form of BlGGT clearly reveal that this peptide sequence is in close spatial proximity to the self-processing and catalytic sites of the enzyme. To probe the role of this conserved sequence, ten mutant enzymes of BlGGT were created through a series of deletion and alanine-scanning mutagenesis. SDS-PAGE and densitometric analyses showed that the intrinsic ability of BlGGT to undergo autocatalytic processing was detrimentally affected by the deletion-associated mutations. However, loss of self-activating capacity was not obviously observed in most of the Ala-replacement mutants. The Ala-replacement mutants had a specific activity comparable to or greater than that of the wild-type enzyme; conversely, all deletion mutants completely lost their enzymatic activity. As compared with BlGGT, S460A and S461S showed greatly enhanced kcat/Km values by 2.73- and 2.67-fold, respectively. The intrinsic tryptophan fluorescence and circular dichroism spectral profiles of Ala-replacement and deletion mutants were typically similar to those of BlGGT. However, heat and guanidine hydrochloride-induced unfolding transitions of the deletion-associated mutant proteins were severely reduced as compared with the wild-type enzyme. The predictive mutant models suggest that the microenvironments required for both self-activation and catalytic reaction of BlGGT can be altered upon mutations.
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