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Joshi V, Jander G. Arabidopsis methionine gamma-lyase is regulated according to isoleucine biosynthesis needs but plays a subordinate role to threonine deaminase. PLANT PHYSIOLOGY 2009; 151:367-78. [PMID: 19571310 PMCID: PMC2735994 DOI: 10.1104/pp.109.138651] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Accepted: 06/22/2009] [Indexed: 05/19/2023]
Abstract
The canonical pathway for isoleucine biosynthesis in plants begins with the conversion of threonine to 2-ketobutyrate by threonine deaminase (OMR1). However, demonstration of methionine gamma-lyase (MGL) activity in Arabidopsis (Arabidopsis thaliana) suggested that production of 2-ketobutyrate from methionine can also lead to isoleucine biosynthesis. Rescue of the isoleucine deficit in a threonine deaminase mutant by MGL overexpression, as well as decreased transcription of endogenous Arabidopsis MGL in a feedback-insensitive threonine deaminase mutant background, shows that these two enzymes have overlapping functions in amino acid biosynthesis. In mgl mutant flowers and seeds, methionine levels are significantly increased and incorporation of [(13)C]Met into isoleucine is decreased, but isoleucine levels are unaffected. Accumulation of free isoleucine and other branched-chain amino acids is greatly elevated in response to drought stress in Arabidopsis. Gene expression analyses, amino acid phenotypes, and labeled precursor feeding experiments demonstrate that MGL activity is up-regulated by osmotic stress but likely plays a less prominent role in isoleucine biosynthesis than threonine deaminase. The observation that MGL makes a significant contribution to methionine degradation, particularly in reproductive tissue, suggests practical applications for silencing the expression of MGL in crop plants and thereby increasing the abundance of methionine, a limiting essential amino acid.
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Affiliation(s)
- Vijay Joshi
- Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, New York 14853, USA
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Heterologous production of methionine-gamma-lyase from Brevibacterium linens in Lactococcus lactis and formation of volatile sulfur compounds. Appl Environ Microbiol 2009; 75:2326-32. [PMID: 19251895 DOI: 10.1128/aem.02417-08] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The conversion of methionine to volatile sulfur compounds (VSCs) is of great importance in flavor formation during cheese ripening and is the focus of biotechnological approaches toward flavor improvement. A synthetic mgl gene encoding methionine-gamma-lyase (MGL) from Brevibacterium linens BL2 was cloned into a Lactococcus lactis expression plasmid under the control of the nisin-inducible promoter PnisA. When expressed in L. lactis and purified as a recombinant protein, MGL was shown to degrade L-methionine as well as other sulfur-containing compounds such as L-cysteine, L-cystathionine, and L-cystine. Overproduction of MGL in recombinant L. lactis also resulted in an increase in the degradation of these compounds compared to the wild-type strain. Importantly, gas chromatography-mass spectrometry analysis identified considerably higher formation of methanethiol (and its oxidized derivatives dimethyl disulfide and dimethyl trisulfide) in reactions containing either purified protein, whole cells, or cell extracts from the heterologous L. lactis strain. This is the first report of production of MGL from B. linens in L. lactis. Given their significance in cheese flavor development, the use of lactic acid bacteria with enhanced VSC-producing abilities could be an efficient way to enhance cheese flavor development.
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Sato D, Karaki T, Shimizu A, Kamei K, Harada S, Nozaki T. Crystallization and preliminary X-ray analysis of L-methionine gamma-lyase 1 from Entamoeba histolytica. Acta Crystallogr Sect F Struct Biol Cryst Commun 2008; 64:697-9. [PMID: 18678935 PMCID: PMC2494978 DOI: 10.1107/s1744309108018691] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2008] [Accepted: 06/20/2008] [Indexed: 11/10/2022]
Abstract
L-Methionine gamma-lyase (MGL) is a pyridoxal phosphate-dependent enzyme that is involved in the degradation of sulfur-containing amino acids. MGL is an attractive drug target against amoebiasis because the mammalian host of its causative agent Entamoeba histolytica lacks MGL. For the development of anti-amoebic agents based on the structure of MGL, one of two MGL isoenzymes (EhMGL1) was crystallized in the monoclinic space group P2(1), with unit-cell parameters a = 99.12, b = 85.38, c = 115.37 A, beta = 101.82 degrees . The crystals diffract to beyond 2.0 A resolution. The presence of a tetramer in the asymmetric unit (4 x 42.4 kDa) gives a Matthews coefficient of 2.8 A(3) Da(-1) and a solvent content of 56%. The structure was solved by the molecular-replacement method and structure refinement is now in progress.
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Affiliation(s)
- Dan Sato
- Institute for Advanced Biosciences, Keio University, 246-2 Mizukami, Kakuganji, Tsuruoka, Yamagata 997-0052, Japan
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Bürgmann H, Howard EC, Ye W, Sun F, Sun S, Napierala S, Moran MA. Transcriptional response of Silicibacter pomeroyi DSS-3 to dimethylsulfoniopropionate (DMSP). Environ Microbiol 2008; 9:2742-55. [PMID: 17922758 DOI: 10.1111/j.1462-2920.2007.01386.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dimethylsufoniopropionate (DMSP) is an abundant organic sulfur compound in the ocean and an important substrate for marine bacterioplankton. The Roseobacter clade of marine alphaproteobacteria, including Silicibacter pomeroyi strain DSS-3, are known to be involved in DMSP degradation in situ. The fate of DMSP has important implications for the global sulfur cycle, but the genes involved in this process and their regulation are largely unknown. S. pomeroyi is capable of performing two major pathways of DMSP degradation, making it an important model organism. Based on the full genome sequence of this strain we designed an oligonucleotide-based microarray for the detection of transcripts of nearly all genes. The array was used to study the transcriptional response of S. pomeroyi cultures to additions of DMSP compared to the non-sulfur compound acetate in a time series experiment. We identified a number of upregulated genes that could be assigned to potential roles in the metabolism of DMSP. DMSP also affected the transcription of genes for transport and metabolism of peptides, amino acids and polyamines. DMSP concentration may thus also play a role as a chemical signal, indicating phytoplankton abundance and eliciting a regulatory response aimed at making maximum use of available nutrients.
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Affiliation(s)
- Helmut Bürgmann
- Department of Marine Sciences, University of Georgia, Athens, GA 30602-3636, USA.
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55
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Sato D, Yamagata W, Harada S, Nozaki T. Kinetic characterization of methionine γ-lyases from the enteric protozoan parasite Entamoeba histolytica against physiological substrates and trifluoromethionine, a promising lead compound against amoebiasis. FEBS J 2008; 275:548-60. [DOI: 10.1111/j.1742-4658.2007.06221.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
This review describes volatiles released into the air by bacteria growing on defined media. Their occurrence, function, and biosynthesis are discussed, and a total of 308 references are cited. An effort has been made to organize the compounds according to their biosynthetic origin.
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Affiliation(s)
- Stefan Schulz
- Institute of Organic Chemistry, Technical University of Braunschweig, Hagenring 30, 38106, Braunschweig, Germany.
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57
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Goyer A, Collakova E, Shachar-Hill Y, Hanson AD. Functional characterization of a methionine gamma-lyase in Arabidopsis and its implication in an alternative to the reverse trans-sulfuration pathway. PLANT & CELL PHYSIOLOGY 2007; 48:232-42. [PMID: 17169919 DOI: 10.1093/pcp/pcl055] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Methionine gamma-lyase (MGL) catalyzes the degradation of L-methionine to alpha-ketobutyrate, methanethiol and ammonia. The Arabidopsis (Arabidopsis thaliana) genome includes a single gene (At1g64660) encoding a protein (AtMGL) with approximately 35% identity to bacterial and protozoan MGLs. When overexpressed in Escherichia coli, AtMGL allowed growth on L-methionine as sole nitrogen source and conferred a high rate of methanethiol emission. The purified recombinant protein exhibited a spectrum typical of pyridoxal 5'-phosphate enzymes, and had high activity toward l-methionine, L-ethionine, L-homocysteine and seleno-L-methionine, but not L-cysteine. Quantitation of mRNA showed that the AtMGL gene is expressed in aerial organs and roots, and that its expression in leaves was increased 2.5-fold by growth on low sulfate medium. Emission of methanethiol from Arabidopsis plants supplied with 10 mM L-methionine was undetectable (<0.5 nmol min(-1) g(-1) FW), suggesting that AtMGL is not an important source of volatile methanethiol. Knocking out the AtMGL gene significantly increased leaf methionine content (9.2-fold) and leaf and root S-methylmethionine content (4.7- and 7-fold, respectively) under conditions of sulfate starvation, indicating that AtMGL carries a significant flux in vivo. In Arabidopsis plantlets fed L-[(35)S]methionine on a low sulfate medium, label was incorporated into protein-bound cysteine as well as methionine, but incorporation into cysteine was significantly (30%) less in the knockout mutant. These data indicate that plants possess an alternative to the reverse trans-sulfuration pathway (methionine-->homocysteine-->cystathionine-->cysteine) in which methanethiol is an intermediate.
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Affiliation(s)
- Aymeric Goyer
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA.
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Alferov KV, Faleev NG, Demidkina TV, Khurs EN, Morozova EA, Khomutov RM. Biologically active organophosphorous analogues of methionine in reactions catalyzed by L-methionine gamma-lyase. DOKL BIOCHEM BIOPHYS 2006; 407:102-5. [PMID: 16776077 DOI: 10.1134/s1607672906020153] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- K V Alferov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, ul. Vavilova 32, Moscow, 117984 Russia
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Sato D, Yamagata W, Kamei K, Nozaki T, Harada S. Expression, purification and crystallization of L-methionine gamma-lyase 2 from Entamoeba histolytica. Acta Crystallogr Sect F Struct Biol Cryst Commun 2006; 62:1034-6. [PMID: 17012806 PMCID: PMC2225178 DOI: 10.1107/s1744309106036694] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2006] [Accepted: 09/11/2006] [Indexed: 11/10/2022]
Abstract
L-Methionine gamma-lyase (MGL) is considered to be an attractive target for rational drug development because the enzyme is absent in mammalian hosts. To enable structure-based design of drugs targeting MGL, one of the two MGL isoenzymes (EhMGL2) was crystallized in the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 88.89, b = 102.68, c = 169.87 A. The crystal diffracted to a resolution of 2.0 A. The presence of a tetramer in the asymmetric unit (4 x 43.1 kDa) gives a Matthews coefficient of 2.2 A(3) Da(-1). The structure was solved by the molecular-replacement method and structure refinement is now in progress.
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Affiliation(s)
- Dan Sato
- Department of Parasitology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan
| | - Wataru Yamagata
- Graduate School of Science and Technology, Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan
| | - Kaeko Kamei
- Graduate School of Science and Technology, Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan
| | - Tomoyoshi Nozaki
- Department of Parasitology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan
| | - Shigeharu Harada
- Graduate School of Science and Technology, Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan
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Manukhov IV, Mamaeva DV, Morozova EA, Rastorguev SM, Faleev NG, Demidkina TV, Zavilgelsky GB. L-methionine γ-lyase from Citrobacter freundii: Cloning of the gene and kinetic parameters of the enzyme. BIOCHEMISTRY (MOSCOW) 2006; 71:361-9. [PMID: 16615855 DOI: 10.1134/s0006297906040031] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
It is shown for the first time for the Enterobacteriaceae family that a gene encoding L-methionine gamma-lyase (MGL) is present in the genome of Citrobacter freundii. Homogeneous enzyme has been purified from C. freundii cells and its N-terminal sequence has been determined. The hybrid plasmid pUCmgl obtained from the C. freundii genomic library contains an EcoRI insert of about 3000 bp, which ensures the appearance of MGL activity when expressed in Escherichia coli TG1 cells. The nucleotide sequence of the EcoRI fragment contains two open reading frames. The first frame (the megL gene) encodes a protein of 398 amino acid residues that has sequence homology with MGLs from different sources. The second frame encodes a protein with sequence homology with proteins belonging to the family of permeases. To overexpress the megL gene it was cloned into pET-15b vector. Recombinant enzyme has been purified and its kinetic parameters have been determined. It is demonstrated that a presence of a hybrid plasmid pUCmgl, containing the megL gene in the E. coli K12 cells, leads to a decrease in efficiency of EcoKI-restriction. It seems likely that decomposition of L-methionine under the action of MGL leads to a decrease in the intracellular content of S-adenosylmethionine. Expression of the megL gene in the C. freundii genome occurs only upon induction by a significant amount of L-methionine.
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Affiliation(s)
- I V Manukhov
- State Research Institute of Genetics and Selection of Industrial Microorganisms, 117545 Moscow, Russia
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