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Sharma E, Lal MK, Gulati A, Gulati A. Biochemical Characterization of γ-Glutamyl Transpeptidase from Bacillus altitudinis IHB B1644 and Its Application in the Synthesis of l-Theanine. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:5592-5599. [PMID: 36999937 DOI: 10.1021/acs.jafc.3c00295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
An extracellular γ-glutamyl transpeptidase (GGT) produced from Bacillus altitudinis IHB B1644 was purified to homogeneity employing ion-exchange chromatography. GGT comprised two subunits of 40 and 22 kDa determined by SDS-PAGE. The maximum enzyme activity was optimal at pH 9 and 37 °C. The purified enzyme was stable from pH 5-10 and <50 °C. Steady-state kinetic studies revealed a Km value of 0.538 mM against γ-GpNA. For substrate specificity, GGT showed highest affinity for l-methionine. The inhibitors' effect demonstrated that serine or threonine and tryptophan residues are essential for enzyme activity. l-Theanine production was optimized by employing a one-variable-at-a-time approach with 60-65% conversion rate. The final reaction consisted of 20 mM l-glutamine, 200 mM ethylamine hydrochloride, and 10 U mL-1 enzyme concentration at 37 °C in Tris-Cl (50 mM, pH 9) for 5 h. l-Theanine was purified using a Dowex 50W X 8 hydrogen form resin and confirmed by HPLC and 1H NMR spectroscopies.
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Affiliation(s)
- Eshita Sharma
- Dietetics & Nutrition Technology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, Himachal Pradesh, India
- Department of Molecular Biology and Biochemistry, Guru Nanak Dev University, Amritsar 143005, Punjab, India
| | - Milan Kumar Lal
- Division of Crop Physiology, Biochemistry & Post Harvest Technology, ICAR-Central Potato Research Institute, Shimla 171001, India
| | - Arvind Gulati
- CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, Himachal Pradesh, India
| | - Ashu Gulati
- Dietetics & Nutrition Technology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, Himachal Pradesh, India
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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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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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4
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Saini M, Kalra S, Kaushik JK, Gupta R. Functional characterization of the extra sequence in the large subunit of γ-glutamyl transpeptidase from Bacillus atrophaeus: Role in autoprocessing and activity. Process Biochem 2021. [DOI: 10.1016/j.procbio.2021.05.004] [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: 11/25/2022]
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5
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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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Magnetic Cross-Linked Enzyme Aggregates of a Transpeptidase-Specialized Variant (N450D) of Bacillus licheniformis γ-Glutamyl Transpeptidase: An Efficient and Stable Biocatalyst for l-Theanine Synthesis. Catalysts 2021. [DOI: 10.3390/catal11020243] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
γ-Glutamyl transpeptidase (GGT) catalyzes the transfer of glutathione’s γ-glutamyl group and related γ-glutamyl amides to water, amino acids or peptides, and utilizes a conserved Thr residue to process its own polypeptide chain into a large and a small subunit that then assemble to produce a catalytically competent enzyme. In this study, the magnetic cross-linked enzyme aggregates (mCLEAs) of a transpeptidase-specialized variant (N450D) of Bacillus licheniformis GGT were successfully prepared with optimized process parameters viz.1.25:1 (v/v) of isopropanol to N450D (0.3 mg/mL) ratio/0.02:1 (w/w) of enzyme to 3-aminopropyl triethoxysilane (APTES)-coated magnetic nanoparticle ratio/20 mM of glutaraldehyde. The prepared magnetic nanoparticles and immobilized enzyme (N450D-mCLEAs) were characterized by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, field-emission scanning electron microscope integrated with energy dispersive X-ray spectroscopy (FESEM/EDS), and superparamagnetic analysis. As compared with free enzyme, N450D-mCLEAs displayed significantly higher heat resistance at temperatures of 55 and 60 °C, and had a greater stability over a storage period of one month. The immobilized enzyme could also be reused for 10 consecutive biocatalytic cycles with no significant reduction in the percent yield of l-theanine. Conclusively, this immobilization strategy surely provides a meaningful glance of developing N450D-mediated biocatalysis for the production of physiologically important γ-glutamyl compounds.
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Enhanced extracellular gamma glutamyl transpeptidase production by overexpressing of PrsA lipoproteins and improving its mRNA stability in Bacillus subtilis and application in biosynthesis of L-theanine. J Biotechnol 2019; 302:85-91. [DOI: 10.1016/j.jbiotec.2019.06.302] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 06/22/2019] [Accepted: 06/25/2019] [Indexed: 11/21/2022]
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8
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Functional role of the conserved glycine residues, Gly481 and Gly482, of the γ-glutamyltranspeptidase from Bacillus licheniformis. Int J Biol Macromol 2017; 109:1182-1188. [PMID: 29162462 DOI: 10.1016/j.ijbiomac.2017.11.116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 11/16/2017] [Accepted: 11/17/2017] [Indexed: 01/17/2023]
Abstract
Six mutants bearing single amino acid substitutions in the small subunit of Bacillus licheniformis γ-glutamyltranspeptudase (BlGGT) have been constructed by site-directed mutagenesis. The resultant enzymes were overexpressed in Escherichia coli and purified by affinity chromatography for biochemical and biophysical characterizations. Replacing Gly481 by either Ala or Glu did affect both autocatalytic processing and catalytic activity of the enzyme, but the substitution of this residue to arginine resulted in an unprocessed enzyme with insignificant catalytic activity. The replacement of another conserved glycine residue, Gly482, by either Ala or Glu caused a significant change in the functional integrity of the enzyme. Moreover, the mutation of Gly482 to arginine led to a marked reduction in the autocatalytic processing. Structural analyses revealed that the fluorescence and circular dichroism properties of mutant proteins were basically consistent with those of BlGGT. However, guanidine hydrochloride (GdnHCl)-induced transitions of most mutants were profoundly reduced in comparison with that of wild-type enzyme. Molecular modeling suggests that the conserved Gly481 and Gly482 residues of BlGGT are located at critical positions to create an environment suitable for both autoprocessing and catalytic reactions.
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Saini M, Bindal S, Gupta R. Heterologous expression of γ-glutamyl transpeptidase from Bacillus atrophaeus GS-16 and its application in the synthesis of γ- d -glutamyl- l -tryptophan, a known immunomodulatory peptide. Enzyme Microb Technol 2017; 99:67-76. [DOI: 10.1016/j.enzmictec.2017.01.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 12/02/2016] [Accepted: 01/05/2017] [Indexed: 10/20/2022]
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10
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Bindal S, Sharma S, Singh TP, Gupta R. Evolving transpeptidase and hydrolytic variants of γ-glutamyl transpeptidase from Bacillus licheniformis by targeted mutations of conserved residue Arg109 and their biotechnological relevance. J Biotechnol 2017; 249:82-90. [PMID: 28365292 DOI: 10.1016/j.jbiotec.2017.03.034] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 03/28/2017] [Accepted: 03/28/2017] [Indexed: 01/04/2023]
Abstract
γ-Glutamyl transpeptidase (GGT) catalyzes the transfer of the γ-glutamyl moiety from donor compounds such as l-glutamine (Gln) and glutathione (GSH) to an acceptor. During the biosynthesis of various γ-glutamyl-containing compounds using GGT enzyme, auto-transpeptidation reaction leads to the formation of unwanted byproducts. Therefore, in order to alter the auto-transpeptidase activity of the GGT enzyme, the binding affinity of Gln should be modified. Structural studies of the Bacillus licheniformis GGT (BlGT) complexed with the glutamic acid has shown that glutamic acid has strong ionic interactions through its α-carboxlic group with the guanidine moiety of Arg109. This interaction appears to be an important contributor for the binding affinity of Gln. In view of this, six mutants of Bacillus licheniformis ER15 GGT (BlGGT) viz. Arg109Lys, Arg109Ser, Arg109Met, Arg109Leu, Arg109Glu and Arg109Phe were prepared. As seen from the structure of BlGT, the mutation of Arg109 to Lys109 may reduce the affinity for Gln to some extent, whereas the other mutations are expected to lower the affinity much more. Biophysical characterization and functional studies revealed that Arg109Lys mutant has increased transpeptidation activity and catalytic efficiency than the other mutants. The Arg109Lys mutant showed high conversion rates for l-theanine synthesis as well. Moreover, the Arg109Met mutant showed increased hydrolytic activity as it completely altered the binding of Gln at the active site. Also, the salt stability of the enzyme was significantly improved on replacing Arg109 by Met109 which is required for hydrolytic applications of GGTs in food industries.
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Affiliation(s)
- Shruti Bindal
- Department of Microbiology, University of Delhi South Campus, New Delhi 110021, India
| | - Sujata Sharma
- Department of Biophysics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India
| | - Tej P Singh
- Department of Biophysics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India
| | - Rani Gupta
- Department of Microbiology, University of Delhi South Campus, New Delhi 110021, India.
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11
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Site-directed mutagenesis of a conserved Asn450 residue of Bacillus licheniformis γ-glutamyltranspeptidase. Int J Biol Macromol 2016; 91:416-25. [DOI: 10.1016/j.ijbiomac.2016.05.101] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 05/27/2016] [Accepted: 05/28/2016] [Indexed: 12/29/2022]
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12
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Walter F, Grenz S, Ortseifen V, Persicke M, Kalinowski J. Corynebacterium glutamicum ggtB encodes a functional γ-glutamyl transpeptidase with γ-glutamyl dipeptide synthetic and hydrolytic activity. J Biotechnol 2015; 232:99-109. [PMID: 26528625 DOI: 10.1016/j.jbiotec.2015.10.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 10/19/2015] [Accepted: 10/22/2015] [Indexed: 12/20/2022]
Abstract
In this work the role of γ-glutamyl transpeptidase in the metabolism of γ-glutamyl dipeptides produced by Corynebacterium glutamicum ATCC 13032 was studied. The enzyme is encoded by the gene ggtB (cg1090) and synthesized as a 657 amino acids long preprotein. Gamma-glutamyl transpeptidase activity was found to be associated with intact cells of C. glutamicum and was abolished upon deletion of ggtB. Bioinformatic analysis indicated that the enzyme is a lipoprotein and is attached to the outer side of the cytoplasmic membrane. Biochemical parameters of recombinant GgtB were determined using the chromogenic substrate γ-glutamyl-p-nitroanilide. Highest activity of the enzyme was measured in sodium bicarbonate buffer at pH 9.6 and 45°C. The KM value was 123μM. GgtB catalyzed the concentration-dependent synthesis and hydrolysis of γ-glutamyl dipeptides and showed strong glutaminase activity. The intracellular concentrations of five γ-glutamyl dipeptides (γ-Glu-Glu, γ-Glu-Gln, γ-Glu-Val, γ-Glu-Leu, γ-Glu-Met) were determined by HPLC-MS and ranged from 0.15 to 0.4mg/g CDW after exponential growth in minimal media. Although deletion and overexpression of ggtB had significant effects on intracellular dipeptide concentrations, it was neither essential for biosynthesis nor catabolism of these dipeptides in vivo.
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Affiliation(s)
- Frederik Walter
- Center for Biotechnology, Bielefeld University, Universitätsstraße 27, 33615 Bielefeld, Germany
| | - Sebastian Grenz
- Center for Biotechnology, Bielefeld University, Universitätsstraße 27, 33615 Bielefeld, Germany
| | - Vera Ortseifen
- Center for Biotechnology, Bielefeld University, Universitätsstraße 27, 33615 Bielefeld, Germany
| | - Marcus Persicke
- Center for Biotechnology, Bielefeld University, Universitätsstraße 27, 33615 Bielefeld, Germany
| | - Jörn Kalinowski
- Center for Biotechnology, Bielefeld University, Universitätsstraße 27, 33615 Bielefeld, Germany.
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13
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Pica A, Chi MC, Chen YY, d'Ischia M, Lin LL, Merlino A. The maturation mechanism of γ-glutamyl transpeptidases: Insights from the crystal structure of a precursor mimic of the enzyme from Bacillus licheniformis and from site-directed mutagenesis studies. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1864:195-203. [PMID: 26536828 DOI: 10.1016/j.bbapap.2015.10.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 10/26/2015] [Accepted: 10/28/2015] [Indexed: 01/20/2023]
Abstract
γ-Glutamyl transpeptidases (γ-GTs) are members of N-terminal nucleophile hydrolase superfamily. They are synthetized as single-chain precursors, which are then cleaved to form mature enzymes. Basic aspects of autocatalytic processing of these pro-enzymes are still unknown. Here we describe the X-ray structure of the precursor mimic of Bacillus licheniformis γ-GT (BlGT), obtained by mutating catalytically important threonine to alanine (T399A-BlGT), and report results of autoprocessing of mutants of His401, Thr415, Thr417, Glu419 and Arg571. Data suggest that Thr417 is in a competent position to activate the catalytic threonine (Thr399) for nucleophilic attack of the scissile peptide bond and that Thr415 plays a major role in assisting the process. On the basis of these new structural results, a possible mechanism of autoprocessing is proposed. This mechanism, which guesses the existence of a six-membered transition state involving one carbonyl and two hydroxyl groups, is in agreement with all the available experimental data collected on γ-GTs from different species and with our new Ala-scanning mutagenesis data.
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Affiliation(s)
- Andrea Pica
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia, Naples I-80126, Italy; Istituto di Biostrutture e Bioimmagini, CNR, Via Mezzocannone, 16, Naples 80133, Italy
| | - Meng-Chun Chi
- Department of Applied Chemistry, National Chiayi University, 300 Syuefu Road, Chiayi City 60004, Taiwan
| | - Yi-Yu Chen
- Department of Applied Chemistry, National Chiayi University, 300 Syuefu Road, Chiayi City 60004, Taiwan
| | - Marco d'Ischia
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia, Naples I-80126, Italy
| | - Long-Liu Lin
- Department of Applied Chemistry, National Chiayi University, 300 Syuefu Road, Chiayi City 60004, Taiwan
| | - Antonello Merlino
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia, Naples I-80126, Italy; Istituto di Biostrutture e Bioimmagini, CNR, Via Mezzocannone, 16, Naples 80133, Italy.
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Prihanto AA, Nonomura Y, Takagi K, Naohara R, Umekawa M, Wakayama M. Novel properties of γ-glutamyltransferase from Pseudomonas syringae with β-aspartyltransferase activity. Biotechnol Lett 2015; 37:2255-63. [DOI: 10.1007/s10529-015-1906-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 06/29/2015] [Indexed: 01/08/2023]
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15
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Gamma-glutamyl transpeptidase from two plant growth promoting rhizosphere fluorescent pseudomonads. Antonie van Leeuwenhoek 2013; 105:45-56. [DOI: 10.1007/s10482-013-0051-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Accepted: 10/04/2013] [Indexed: 12/31/2022]
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16
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Liu Y, Yuan Y, Lei XY, Yang H, Ibrahim S, Huang W. Purification and characterisation of two enzymes related to endogenous formaldehyde in Lentinula edodes. Food Chem 2013; 138:2174-9. [DOI: 10.1016/j.foodchem.2012.12.038] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 12/04/2012] [Accepted: 12/12/2012] [Indexed: 11/30/2022]
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17
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Lin LL, Merlino A. Heterogeneous nucleation helps the search for initial crystallization conditions of γ-glutamyl transpeptidase from Bacillus licheniformis. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013; 69:669-72. [PMID: 23722850 DOI: 10.1107/s1744309113012165] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 05/03/2013] [Indexed: 11/10/2022]
Abstract
Here, the crystallization and preliminary X-ray diffraction studies of Bacillus licheniformis γ-glutamyl transpeptidase (BlGT) are reported. The serendipitous finding of heterogeneous nucleants in the initial experiments provided the first crystallization conditions for the protein. Crystals were grown by hanging-drop vapour diffusion using a precipitant solution consisting of 20%(w/v) PEG 3350, 0.2 M magnesium chloride hexahydrate, 0.1 M Tris-HCl pH 8.2. The protein crystallized in the orthorhombic space group P2(1)2(1)2(1), with one heterodimer per asymmetric unit and unit-cell parameters a = 60.90, b = 61.97, c = 148.24 Å. The BlGT crystals diffracted to 2.95 Å resolution.
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Affiliation(s)
- Long Liu Lin
- Department of Applied Chemistry, National Chiayi University, 300 Syuefu Road, Chiayi City 60004, Taiwan
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18
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Castellano I, Merlino A. Gamma-Glutamyl Transpeptidases: Structure and Function. GAMMA-GLUTAMYL TRANSPEPTIDASES 2013. [DOI: 10.1007/978-3-0348-0682-4_1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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19
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Rajput R, Verma VV, Chaudhary V, Gupta R. A hydrolytic γ-glutamyl transpeptidase from thermo-acidophilic archaeon Picrophilus torridus: binding pocket mutagenesis and transpeptidation. Extremophiles 2012; 17:29-41. [PMID: 23104165 DOI: 10.1007/s00792-012-0490-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 10/09/2012] [Indexed: 11/26/2022]
Abstract
γ-Glutamyl transpeptidase of a thermo-acidophilic archaeon Picrophilus torridus was cloned and expressed using E. coli Rosetta-pET 51b(+) expression system. The enzyme was expressed at 37 °C/200 rpm with γ-GT production of 1.99 U/mg protein after 3 h of IPTG induction. It was improved nearby 10-fold corresponding to 18.92 U/mg protein in the presence of 2 % hexadecane. The enzyme was purified by Ni(2+)-NTA with a purification fold of 3.6 and recovery of 61 %. It was synthesized as a precursor heterodimeric protein of 47 kDa with two subunits of 30 kDa and 17 kDa, respectively, as revealed by SDS-PAGE and western blot. The enzyme possesses hydrolase activity with optima at pH 7.0 and 55 °C. It was thermostable with a t (1/2) of 1 h at 50 °C and 30 min at 60 °C, and retained 100 % activity at 45 °C even after 24 h. It was inhibited by azaserine and DON and PMSF. Ptγ-GT shared 37 % sequence identity and 53 % homology with an extremophile γ-GT from Thermoplasma acidophilum. Functional residues identified by in silico approaches were further validated by site-directed mutagenesis where Tyr327 mutated by Asn327 introduced significant transpeptidase activity.
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Affiliation(s)
- Rinky Rajput
- Department of Microbiology, University of Delhi, South Campus, New Delhi, 110021, India
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Castellano I, Merlino A. γ-Glutamyltranspeptidases: sequence, structure, biochemical properties, and biotechnological applications. Cell Mol Life Sci 2012; 69:3381-94. [PMID: 22527720 PMCID: PMC11115026 DOI: 10.1007/s00018-012-0988-3] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 03/27/2012] [Accepted: 03/29/2012] [Indexed: 12/12/2022]
Abstract
γ-Glutamyltranspeptidases (γ-GTs) are ubiquitous enzymes that catalyze the hydrolysis of γ-glutamyl bonds in glutathione and glutamine and the transfer of the released γ-glutamyl group to amino acids or short peptides. These enzymes are involved in glutathione metabolism and play critical roles in antioxidant defense, detoxification, and inflammation processes. Moreover, γ-GTs have been recently found to be involved in many physiological disorders, such as Parkinson's disease and diabetes. In this review, the main biochemical and structural properties of γ-GTs isolated from different sources, as well as their conformational stability and mechanism of catalysis, are described and examined with the aim of contributing to the discussion on their structure-function relationships. Possible applications of γ-glutamyltranspeptidases in different fields of biotechnology and medicine are also discussed.
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Affiliation(s)
- Immacolata Castellano
- Institute of Protein Biochemistry, CNR, via Pietro Castellino 111, 80131 Naples, Italy
- Present Address: Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy
| | - Antonello Merlino
- Department of Chemical Sciences, University of Naples ‘Federico II’, Complesso Universitario di Monte Sant’Angelo, via cintia, 80126 Naples, Italy
- Institute of Biostructures and Bioimages, CNR, via Mezzocannone 16, 80100 Naples, Italy
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Chi MC, Chen YY, Lo HF, Lin LL. Experimental evidence for the involvement of amino acid residue Glu398 in the autocatalytic processing of Bacillus licheniformis γ-glutamyltranspeptidase. FEBS Open Bio 2012; 2:298-304. [PMID: 23772362 PMCID: PMC3678132 DOI: 10.1016/j.fob.2012.09.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Revised: 09/25/2012] [Accepted: 09/25/2012] [Indexed: 11/18/2022] Open
Abstract
The role of glutamate 398 in the autocatalytic processing of Bacillus licheniformis γ-glutamyltranspeptidase (BlGGT) was explored by site-directed mutagenesis. This glutamate was substituted by either alanine, aspartate, arginine or glutamine and the expressed mutant enzymes were purified to apparent homogeneity with metal-affinity chromatography. SDS–PAGE analysis showed that E398A, E398D and E398K were unable to process themselves into a large and a small subunit. However, E398Q was not only able to process itself, but also had a catalytic activity comparable to that of BlGGT. As compared with the wild-type enzyme, no significant change in circular dichroism spectra was observed for the mutant proteins. Thermal unfolding of BlGGT, E398A, E398D, E398K and E398Q followed the two-state unfolding process with a transition point (Tm) of 47.7–69.4 °C. Tryptophan fluorescence spectra of the mutant enzymes were different from the wild-type protein in terms of fluorescence intensity. Native BlGGT started to unfold beyond ∼1.92 M guanidine hydrochloride (GdnHCl) and reached an unfolded intermediate, [GdnHCl]0.5, N–U, at 3.07 M equivalent to free energy change (ΔGN−UH2O) of 14.53 kcal/mol for the N → U process, whereas the denaturation midpoints for the mutant enzymes were 1.31–2.99 M equivalent to ΔGN−UH2O of 3.29–12.05 kcal/mol. Taken together, these results strongly suggest that the explored glutamate residue is indeed important for the autocatalytic processing of BlGGT.
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Affiliation(s)
- Meng-Chun Chi
- Department of Applied Chemistry, National Chiayi University, Taiwan
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Enzymatic characterization of Bacillus licheniformis γ-glutamyltranspeptidase fused with N-terminally truncated forms of Bacillus sp. TS-23 α-amylase. Enzyme Microb Technol 2012; 51:86-94. [DOI: 10.1016/j.enzmictec.2012.04.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 04/18/2012] [Accepted: 04/21/2012] [Indexed: 11/17/2022]
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