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Ling F, Fan Y, Wang Z, Xie N, Li J, Wang G, Feng J. Combined transcriptome and metabolome analysis reveal key regulatory genes and pathways of feed conversion efficiency of oriental river prawn Macrobrachium nipponense. BMC Genomics 2023; 24:267. [PMID: 37208591 DOI: 10.1186/s12864-023-09317-1] [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: 12/12/2022] [Accepted: 04/17/2023] [Indexed: 05/21/2023] Open
Abstract
BACKGROUND Oriental river prawn Macrobrachium nipponense is an economically important aquaculture species in China, Japan, and Vietnam. In commercial prawn farming, feed cost constitutes about 50 to 65% of the actual variable cost. Improving feed conversion efficiency in prawn culture will not only increase economic benefit, but also save food and protect the environment. The common indicators used for feed conversion efficiency include feed conversion ratio (FCR), feed efficiency ratio (FER), and residual feed intake (RFI). Among these, RFI is much more suitable than FCR and FER during the genetic improvement of feed conversion efficiency for aquaculture species. RESULTS In this study, the transcriptome and metabolome of hepatopancreas and muscle of M. nipponense from high RFI low RFI groups, which identified after culture for 75 days, were characterized using combined transcriptomic and metabolomic analysis. A total of 4540 differentially expressed genes (DEGs) in hepatopancreas, and 3894 DEGs in muscle were identified, respectively. The DEGs in hepatopancreas were mainly enriched in KEGG pathways including the metabolism of xenobiotics by cytochrome P450 (down-regulated), fat digestion and absorption (down-regulated) and aminoacyl-tRNA biosynthesis (up-regulated), etc. The DEGs in muscle were mainly enriched in KEGG pathways including the protein digestion and absorption (down-regulated), glycolysis/gluconeogenesis (down-regulated), and glutathione metabolism (up-regulated), etc. At the transcriptome level, the RFI of M. nipponense was mainly controlled in biological pathways such as the high immune expression and the reduction of nutrients absorption capacity. A total of 445 and 247 differently expressed metabolites (DEMs) were identified in the hepatopancreas and muscle, respectively. At the metabolome level, the RFI of M. nipponense was affected considerably by amino acid and lipid metabolism. CONCLUSIONS M. nipponense from higher and lower RFI groups have various physiological and metabolic capability processes. The down-regulated genes, such as carboxypeptidase A1, 6-phosphofructokinase, long-chain-acyl-CoA dehydrogenase, et. al., in digestion and absorption of nutrients, and the up-regulated metabolites, such as aspirin, lysine, et. al., in response to immunity could be potential candidate factors contributed to RFI variation for M. nipponense. Overall, these results would provide new insights into the molecular mechanism of feed conversion efficiency and assist in selective breeding to improve feed conversion efficiency in M. nipponense.
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Affiliation(s)
- Feiyue Ling
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai, 201306, China
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, 201306, China
| | - Yaoran Fan
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai, 201306, China
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, 201306, China
| | - Zefei Wang
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai, 201306, China
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, 201306, China
| | - Nan Xie
- Hangzhou Academy of Agricultural Sciences, Hangzhou, 310012, China
| | - Jiale Li
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai, 201306, China
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, 201306, China
| | - Guiling Wang
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai, 201306, China.
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, 201306, China.
| | - Jianbin Feng
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai, 201306, China.
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, 201306, China.
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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: 32] [Impact Index Per Article: 8.0] [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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3
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Oliva F, Flores-Canales JC, Pieraccini S, Morelli CF, Sironi M, Schiøtt B. Simulating Multiple Substrate-Binding Events by γ-Glutamyltransferase Using Accelerated Molecular Dynamics. J Phys Chem B 2020; 124:10104-10116. [PMID: 33112625 DOI: 10.1021/acs.jpcb.0c06907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
γ-Glutamyltransferase (GGT) is an enzyme that uses γ-glutamyl compounds as substrates and catalyzes their transfer to a water molecule or an acceptor substrate with varied physiological function in bacteria, plants, and animals. Crystal structures of GGT are known for different species and in different states of the chemical reaction; however, the structural dynamics of the substrate binding to the catalytic site of GGT are unknown. Here, we modeled Escherichia coli GGT's glutamine binding by using a swarm of accelerated molecular dynamics (aMD) simulations. Characterization of multiple binding events identified three structural binding motifs composed of polar residues in the binding pocket that govern glutamine binding into the active site. Simulated open and closed conformations of a lid-loop protecting the binding cavity suggest its role as a gating element by allowing or blocking substrates entry into the binding pocket. Partially open states of the lid-loop are accessible within thermal fluctuations, while the estimated free energy cost of a complete open state is 2.4 kcal/mol. Our results suggest that both specific electrostatic interactions and GGT conformational dynamics dictate the molecular recognition of substrate-GGT complexes.
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Affiliation(s)
- Francesco Oliva
- Dipartimento di Chimica, Università degli studi di Milano, Via Golgi 19, 20133 Milano, Italy
| | - Jose C Flores-Canales
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus, Denmark
| | - Stefano Pieraccini
- Dipartimento di Chimica, Università degli studi di Milano, Via Golgi 19, 20133 Milano, Italy
| | - Carlo F Morelli
- Dipartimento di Chimica, Università degli studi di Milano, Via Golgi 19, 20133 Milano, Italy
| | - Maurizio Sironi
- Dipartimento di Chimica, Università degli studi di Milano, Via Golgi 19, 20133 Milano, Italy
| | - Birgit Schiøtt
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus, Denmark
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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: 0.3] [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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5
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Lisheng X, Guizhen G, Xingtao Z, Mengting W. Enzymatic synthesis of γ-glutamylmethylamide from L-glutamylhydrazine and methylamine catalysed by immobilized recombinant γ-glutamyltranspeptidase. BIOCATAL BIOTRANSFOR 2018. [DOI: 10.1080/10242422.2018.1459577] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Xu Lisheng
- Department of Life and Food Science, Suzhou University, Suzhou, China
| | - Gao Guizhen
- Department of Life and Food Science, Suzhou University, Suzhou, China
| | - Zhang Xingtao
- Department of Life and Food Science, Suzhou University, Suzhou, China
| | - Wang Mengting
- Department of Life and Food Science, Suzhou University, Suzhou, China
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6
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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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7
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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: 0.9] [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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8
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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: 1.6] [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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9
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van der Stel AX, Wösten M. Campylobacter jejuni γ-glutamyltranspeptidase Activity Assay. Bio Protoc 2016. [DOI: 10.21769/bioprotoc.1747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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10
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van der Stel AX, van Mourik A, Łaniewski P, van Putten JPM, Jagusztyn-Krynicka EK, Wösten MMSM. The Campylobacter jejuni RacRS two-component system activates the glutamate synthesis by directly upregulating γ-glutamyltranspeptidase (GGT). Front Microbiol 2015; 6:567. [PMID: 26097472 PMCID: PMC4456614 DOI: 10.3389/fmicb.2015.00567] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 05/24/2015] [Indexed: 11/15/2022] Open
Abstract
The highly conserved enzyme γ-glutamyltranspeptidase (GGT) plays an important role in metabolism of glutathione and glutamine. Yet, the regulation of ggt transcription in prokaryotes is poorly understood. In the human pathogen Campylobacter jejuni, GGT is important as it contributes to persistent colonization of the gut. Here we show that the GGT activity in C. jejuni is dependent on a functional RacRS (reduced ability to colonize) two-component system. Electrophoretic mobility shift and luciferase reporter assays indicate that the response regulator RacR binds to a promoter region ~80 bp upstream of the ggt transcriptional start site, which contains a recently identified RacR DNA binding consensus sequence. RacR needs to be phosphorylated to activate the transcription of the ggt gene, which is the case under low oxygen conditions in presence of alternative electron acceptors. A functional GGT and RacR are needed to allow C. jejuni to grow optimally on glutamine as sole carbon source under RacR inducing conditions. However, when additional carbon sources are present C. jejuni is capable of utilizing glutamine independently of GGT. RacR is the first prokaryotic transcription factor known to directly up-regulate both the cytoplasmic [glutamine-2-oxoglutarate aminotransferase (GOGAT)] as well as the periplasmic (GGT) production of glutamate.
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Affiliation(s)
| | - Andries van Mourik
- Department of Infectious Diseases and Immunology, Utrecht University, Utrecht Netherlands
| | - Paweł Łaniewski
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw Poland
| | - Jos P M van Putten
- Department of Infectious Diseases and Immunology, Utrecht University, Utrecht Netherlands
| | - Elżbieta K Jagusztyn-Krynicka
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw Poland
| | - Marc M S M Wösten
- Department of Infectious Diseases and Immunology, Utrecht University, Utrecht Netherlands
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Lv XB, Lian GY, Wang HR, Song E, Yao H, Wang MH. Long noncoding RNA HOTAIR is a prognostic marker for esophageal squamous cell carcinoma progression and survival. PLoS One 2013; 8:e63516. [PMID: 23717443 DOI: 10.1371/journal.pone] [Citation(s) in RCA: 536] [Impact Index Per Article: 44.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 04/03/2013] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND It is currently unclear whether the expression of HOX transcript antisense RNA (HOTAIR) correlates with the progression of esophageal cancer. The aim of this study was to examine HOTAIR expression in patients with esophageal squamous cell cancer (ESCC) and explore its clinical significance. METHODS Differences in the expression of HOTAIR were examined via in situ hybridization (ISH) and quantitative reverse transcriptase PCR (qRT-PCR). The prognostic significance was evaluated using Kaplan-Meier and Cox regression analyses. Proliferation, colony formation and migration assays were performed in ESCC cell lines to determine the function of HOTAIR in the progression of ESCC in vitro. RESULTS A notably higher level of HOTAIR expression was found in ESCC tissues. High expression levels of HOTAIR in ESCC patients correlated positively with clinical stage, TNM classification, histological differentiation and vital status. HOTAIR expression was found to be an independent prognostic factor in ESCC patients. ESCC patients who expressed high levels of HOTAIR had substantially lower overall 5-year survival rates than HOTAIR-negative patients. In vitro assays of ESCC cell lines demonstrated that HOTAIR mediated the proliferation, colony formation and migratory capacity of ESCC cells. CONCLUSION HOTAIR is a potential biomarker for ESCC prognosis, and the dysregulation of HOTAIR may play an important role in ESCC progression.
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Affiliation(s)
- Xiao-Bin Lv
- Medical Research Center Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
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12
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Rossi M, Bolz C, Revez J, Javed S, El-Najjar N, Anderl F, Hyytiäinen H, Vuorela P, Gerhard M, Hänninen ML. Evidence for conserved function of γ-glutamyltranspeptidase in Helicobacter genus. PLoS One 2012; 7:e30543. [PMID: 22348013 PMCID: PMC3279353 DOI: 10.1371/journal.pone.0030543] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 12/19/2011] [Indexed: 12/14/2022] Open
Abstract
The confounding consequences of Helicobacter bilis infection in experimental mice populations are well recognized, but the role of this bacterium in human diseases is less known. Limited data are available on virulence determinants of this species. In Helicobacter pylori, γ-glutamyltranspeptidase (γGT) contributes to the colonization of the gastric mucosa and to the pathogenesis of peptic ulcer. The role of γGT in H. bilis infections remains unknown. The annotated genome sequence of H. bilis revealed two putative ggt genes and our aim was to characterize these H. bilis γGT paralogues. We performed a phylogenetic analysis to understand the evolution of Helicobacter γGTs and to predict functional activities of these two genes. In addition, both copies of H. bilis γGTs were expressed as recombinant proteins and their biochemical characteristics were analysed. Functional complementation of Esherichia coli deficient in γGT activity and deletion of γGT in H. bilis were performed. Finally, the inhibitory effect of T-cell and gastric cell proliferation by H. bilis γGT was assessed. Our results indicated that one gene is responsible for γGT activity, while the other showed no γGT activity due to lack of autoprocessing. Although both H. bilis and H. pylori γGTs exhibited a similar affinity to L-Glutamine and γ-Glutamyl-p-nitroanilide, the H. bilis γGT was significantly less active. Nevertheless, H. bilis γGT inhibited T-cell proliferation at a similar level to that observed for H. pylori. Finally, we showed a similar suppressive influence of both H. bilis and H. pylori γGTs on AGS cell proliferation mediated by an apoptosis-independent mechanism. Our data suggest a conserved function of γGT in the Helicobacter genus. Since γGT is present only in a few enterohepatic Helicobacter species, its expression appears not to be essential for colonization of the lower gastrointestinal tract, but it could provide metabolic advantages in colonization capability of different niches.
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Affiliation(s)
- Mirko Rossi
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
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Pica A, Russo Krauss I, Castellano I, Rossi M, La Cara F, Graziano G, Sica F, Merlino A. Exploring the unfolding mechanism of γ-glutamyltranspeptidases: the case of the thermophilic enzyme from Geobacillus thermodenitrificans. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1824:571-7. [PMID: 22322192 DOI: 10.1016/j.bbapap.2012.01.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 01/19/2012] [Accepted: 01/23/2012] [Indexed: 10/14/2022]
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 generally synthesized as precursor proteins, which undergo an intra-molecular autocatalytic cleavage yielding a large and a small subunit. In this study, circular dichroism and intrinsic fluorescence measurements have been used to investigate the structural features and the temperature- and guanidinium hydrochloride (GdnHCl)-induced unfolding of the mature form of the γ-GT from Geobacillus thermodenitrificans (GthGT) and that of its T353A mutant, which represents a mimic of the precursor protein. Data indicate that a) the mutant and the mature GthGT have a different secondary structure content and a slightly different exposure of hydrophobic regions, b) the thermal unfolding processes of both GthGT forms occur through a three-state model, characterized by a stable intermediate species, whereas chemical denaturations proceed through a single transition, c) both GthGT forms exhibit remarkable stability against temperature, but they do not display a strong resistance to the denaturing action of GdnHCl. These findings suggest that electrostatic interactions significantly contribute to the protein stability and that both the precursor and the mature form of GthGT assume compact and stable conformations to resist to the extreme temperatures where G. thermodenidrificans lives. Owing to its thermostability and unique catalytic properties, GthGT is an excellent candidate to be used as a glutaminase in food industry.
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Affiliation(s)
- Andrea Pica
- Department of Chemical Sciences, University of Naples, Naples, Italy
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Murty NAR, Tiwary E, Sharma R, Nair N, Gupta R. γ-Glutamyl transpeptidase from Bacillus pumilus KS 12: decoupling autoprocessing from catalysis and molecular characterization of N-terminal region. Enzyme Microb Technol 2011; 50:159-64. [PMID: 22305170 DOI: 10.1016/j.enzmictec.2011.08.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 08/17/2011] [Accepted: 08/23/2011] [Indexed: 11/25/2022]
Abstract
Gamma glutamyl transpeptidase from Bacillus pumilus KS12 (GGTBP) was cloned, expressed in pET-28-E. coli expression system as a heterodimeric enzyme with molecular weights of 45 and 20 kDa for large and small subunit, respectively. It was purified by nickel affinity chromatography with hydrolytic and transpeptidase activity of 1.82 U/mg and 4.35 U/mg, respectively. Sequence analysis revealed that GGTBP was most closely related to Bacillus licheniformis GGT and had all the catalytic residues and nucleophiles for autoprocessing recognized from E. coli. It was optimally active at pH 8 and 60°C. It exhibited pH stability from pH 6-9 and high thermostability with t(1/2) of 15 min at 70°C. It had K(m), V(max) of 0.045 mM, 4.35 μmol/mg/min, respectively. Decoupling of autoprocessing by co-expressing large and small subunit in pET-Duet1-E. coli expression system yielded active enzyme with transpeptidase activity of 5.31 U/mg. Though N-terminal truncations of rGGTBP upto 95 aa did not affect autoprocessing of GGT however activity was lost with truncation beyond 63 aa.
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Affiliation(s)
- N Apurva Ratan Murty
- Department of Microbiology, University of Delhi, South Campus, New Delhi 110021, India
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15
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Role of the conserved Thr399 and Thr417 residues of Bacillus licheniformis gamma-Glutamyltranspeptidase as evaluated by mutational analysis. Curr Microbiol 2009; 59:101-6. [PMID: 19340483 DOI: 10.1007/s00284-009-9403-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Revised: 03/10/2009] [Accepted: 03/10/2009] [Indexed: 10/20/2022]
Abstract
Role of the conserved Thr399 and Thr417 residues of Bacillus licheniformis gamma-glutamyltranspeptidase (BlGGT) was investigated by site-directed mutagenesis. Substitutions of Thr399 and Thr417 of BlGGT with Ser resulted in a dramatic reduction in enzymatic activity. A complete loss of the GGT activity was observed in T399A, T399C, T417A, and T417K mutant enzymes. Furthermore, mutations on these two residues impaired the capability of autocatalytic processing of the enzyme. In vitro maturation experiments showed that BlGGT mutant precursors, pro-T399S, pro-T417S, and pro-T417A, could precede a time-dependent autocatalytic process to generate the 44.9- and 21.7-kDa subunits; however, the processed T417A had no enzymatic activity. Measurement of intrinsic tryptophan fluorescence revealed alteration of the microenvironment of aromatic amino acid residues, while Far-UV circular dichroism spectra were nearly identical for wild-type and mutant enzymes. These results suggest that residues Thr399 and Thr417 are important for BlGGT in the enzymatic maturation and reaction.
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