1
|
Anufrieva NV, Morozova EA, Revtovich SV, Bazhulina NP, Timofeev V, Tkachev YV, Faleev N, Nikulin AD, Demidkina TV. Serine 339 in the Catalysis of γ- and β-Elimination Reactions. Acta Naturae 2022; 14:50-61. [PMID: 35923564 PMCID: PMC9307983 DOI: 10.32607/actanaturae.11242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 07/21/2021] [Indexed: 11/20/2022] Open
Abstract
Serine 339 of the active site of Citrobacter freundii
methionine γ-lyase (MGL) is a conserved amino acid in most
pyridoxal 5’-phosphate-dependent enzymes of the cystathionine
β-lyase subclass, to which MGL belongs. The reaction mechanism of the
MGL-catalyzed γ-elimination reaction is poorly explored. We replaced
serine 339 with alanine using site-directed mutagenesis. The replacement of
serine 339 with alanine led to a significant (by two orders of magnitude)
decrease in efficiency in the catalysis of the γ- and β-elimination
reactions by the mutant form of the enzyme. The exchange rates of the C-α-
and C-β-protons in the amino acids in complexes consisting of the enzyme
and competitive inhibitors decreased by one-two orders of magnitude. The
spectral characteristics of the mutant form indicated that the replacement did
not lead to significant changes in the conformation and tautomerism of MGL
internal aldimine. We crystallized the holoenzyme and determined its spatial
structure at 1.7 E resolution. The replacement of serine 339 with alanine did
not affect the overall course of the polypeptide chain of the MGL subunit and
the tetrameric enzyme structure. An analysis of the obtained kinetic and
spectral data, as well as the known spatial structures of C. freundii
MGL, indicates that serine 339 is necessary for efficient catalysis of
γ- and β-elimination reactions at the stage of C-α-proton
abstraction from the external aldimine, the γ-elimination reaction at the
stages of coenzyme C4’-atom protonation, and C-β-proton abstraction
from a ketimine intermediate.
Collapse
Affiliation(s)
- N. V. Anufrieva
- Engelhardt Institute of Molecular Biology of the Russian Academy of Sciences, Moscow, 119991 Russia
| | - E. A. Morozova
- Engelhardt Institute of Molecular Biology of the Russian Academy of Sciences, Moscow, 119991 Russia
| | - S. V. Revtovich
- Engelhardt Institute of Molecular Biology of the Russian Academy of Sciences, Moscow, 119991 Russia
| | - N. P. Bazhulina
- Engelhardt Institute of Molecular Biology of the Russian Academy of Sciences, Moscow, 119991 Russia
| | - V.P. Timofeev
- Engelhardt Institute of Molecular Biology of the Russian Academy of Sciences, Moscow, 119991 Russia
| | - Ya. V. Tkachev
- Engelhardt Institute of Molecular Biology of the Russian Academy of Sciences, Moscow, 119991 Russia
| | - N.G. Faleev
- Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences, Moscow, 119991 Russia
| | - A. D. Nikulin
- Institute of Protein Research of the Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia
| | - T. V. Demidkina
- Engelhardt Institute of Molecular Biology of the Russian Academy of Sciences, Moscow, 119991 Russia
| |
Collapse
|
2
|
Zhu WY, Niu K, Liu P, Fan YH, Liu ZQ, Zheng YG. Identification and Characterization of an O-Succinyl-L-Homoserine Sulfhydrylase From Thioalkalivibrio sulfidiphilus. Front Chem 2021; 9:672414. [PMID: 33937207 PMCID: PMC8080516 DOI: 10.3389/fchem.2021.672414] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 03/23/2021] [Indexed: 11/13/2022] Open
Abstract
L-methionine is an important natural amino acid with broad application prospects. A novel gene encoding the enzyme with the ability to catalyze O-succinyl-L-homoserine (OSH) to L-methionine was screened and characterized. The recombinant O-succinyl-L-homoserine sulfhydrylase from Thioalkalivibrio sulfidiphilus (tsOSHS) exhibited maximum activity at 35°C and pH 6.5. OSHS displayed an excellent thermostability with a half-life of 21.72 h at 30°C. Furthermore, the activity of OSHS increased 115% after Fe2+ added. L-methionine was obtained with a total yield reaching 42.63 g/L under the concentration of O-succinyl-L-homoserine 400 mM (87.6 g/L). These results indicated that OSHS is a potential candidate for applying in the large-scale bioproduction of L-methionine.
Collapse
Affiliation(s)
- Wen-Yuan Zhu
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, China.,Key Laboratory of Bioorganic Synthesis of Zhejiang, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Kun Niu
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, China.,Key Laboratory of Bioorganic Synthesis of Zhejiang, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Peng Liu
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, China.,Key Laboratory of Bioorganic Synthesis of Zhejiang, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Yu-Hang Fan
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, China.,Key Laboratory of Bioorganic Synthesis of Zhejiang, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Zhi-Qiang Liu
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, China.,Key Laboratory of Bioorganic Synthesis of Zhejiang, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Yu-Guo Zheng
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, China.,Key Laboratory of Bioorganic Synthesis of Zhejiang, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| |
Collapse
|
3
|
Wei Y, Gao J, Liu D, Li Y, Liu W. Adaptational changes in physiological and transcriptional responses of Bifidobacterium longum involved in acid stress resistance after successive batch cultures. Microb Cell Fact 2019; 18:156. [PMID: 31514746 PMCID: PMC6743126 DOI: 10.1186/s12934-019-1206-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 09/04/2019] [Indexed: 12/13/2022] Open
Abstract
Bifidobacterium inhabiting the human and animal intestinal tract is known for its health-promoting effect. Tolerance to acid stress is crucial for bifidobacteria to survive and then exert their beneficial effects in the gut. A long-term adaptation in successive batch cultures was used as evolutionary engineering strategy to improve acid stress tolerance in an industrial probiotic strain, B. longum JDM301. Its derivative, JDM301AR showed higher resistance to several stress conditions, including acid stress than the parental strain, JDM301. To better understand bifidobacterial acid stress response, the changes of fatty acid (FA) in cell membrane of these two strains were determined. A shift in the production of FA in cell membrane, characterized by increased C14:0 was found, when JDM301AR was exposed to low-pH environment. It was implied that the increased production of C14:0 is associated with the acquisition of acid-tolerant phenotype for JDM301AR. High-throughput RNA-sequencing was performed to analyze the changes of gene expression profile after acid-exposure. The transcriptional profiles of JDM301AR and JDM301 under normal condition and acid stress were compared to reveal the different acid response between them. A total of 5 genes involved in FA metabolism were upregulated and no downregulated genes were found in response to acid stress in JDM301AR. The up-regulated BLJ_0565 and BLJ_1105 may play important roles in the modification of membrane FA composition of JDM301AR after acid exposure. Overall, these results suggested that successive batch cultures induced the acid stress tolerance of B. longum involved in transcriptional and physiological responses, including modification of cell wall and cell membrane, metabolism of amino acid and neutralization of internal pH by strengthening NH3 production and transport.
Collapse
Affiliation(s)
- Yanxia Wei
- Jiangsu Key Laboratory of Immunity and Metabolism, Laboratory of Infection and Immunity, Department of Pathogenic Biology and Immunology/School of Stomatology, Xuzhou Medical University, Xuzhou, 22104, Jiangsu, China.
| | - Jing Gao
- Jiangsu Key Laboratory of Immunity and Metabolism, Laboratory of Infection and Immunity, Department of Pathogenic Biology and Immunology/School of Stomatology, Xuzhou Medical University, Xuzhou, 22104, Jiangsu, China
| | - Dianbin Liu
- Jiangsu Key Laboratory of Immunity and Metabolism, Laboratory of Infection and Immunity, Department of Pathogenic Biology and Immunology/School of Stomatology, Xuzhou Medical University, Xuzhou, 22104, Jiangsu, China
| | - Yang Li
- Jiangsu Key Laboratory of Immunity and Metabolism, Laboratory of Infection and Immunity, Department of Pathogenic Biology and Immunology/School of Stomatology, Xuzhou Medical University, Xuzhou, 22104, Jiangsu, China
| | - Wenli Liu
- Jiangsu Key Laboratory of Immunity and Metabolism, Laboratory of Infection and Immunity, Department of Pathogenic Biology and Immunology/School of Stomatology, Xuzhou Medical University, Xuzhou, 22104, Jiangsu, China
| |
Collapse
|
4
|
Sato D, Shiba T, Mizuno S, Kawamura A, Hanada S, Yamada T, Shinozaki M, Yanagitani M, Tamura T, Inagaki K, Harada S. The hyperthermophilic cystathionine γ-synthase from the aerobic crenarchaeon Sulfolobus tokodaii: expression, purification, crystallization and structural insights. Acta Crystallogr F Struct Biol Commun 2017; 73:152-158. [PMID: 28291751 PMCID: PMC5349309 DOI: 10.1107/s2053230x17002011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 02/07/2017] [Indexed: 11/10/2022] Open
Abstract
Cystathionine γ-synthase (CGS; EC 2.5.1.48), a pyridoxal 5'-phosphate (PLP)-dependent enzyme, catalyzes the formation of cystathionine from an L-homoserine derivative and L-cysteine in the first step of the transsulfuration pathway. Recombinant CGS from the thermoacidophilic archaeon Sulfolobus tokodaii (StCGS) was overexpressed in Escherichia coli and purified to homogeneity by heat treatment followed by hydroxyapatite and gel-filtration column chromatography. The purified enzyme shows higher enzymatic activity at 353 K under basic pH conditions compared with that at 293 K. Crystallization trials yielded three crystal forms from different temperature and pH conditions. Form I crystals (space group P21; unit-cell parameters a = 58.4, b = 149.3, c = 90.2 Å, β = 108.9°) were obtained at 293 K under acidic pH conditions using 2-methyl-2,4-pentanediol as a precipitant, whereas under basic pH conditions the enzyme crystallized in form II at 293 K (space group C2221; unit-cell parameters a = 117.7, b = 117.8, c = 251.3 Å) and in form II' at 313 K (space group C2221; unit-cell parameters a = 107.5, b = 127.7, c = 251.1 Å) using polyethylene glycol 3350 as a precipitant. X-ray diffraction data were collected to 2.2, 2.9 and 2.7 Å resolution for forms I, II and II', respectively. Structural analysis of these crystal forms shows that the orientation of the bound PLP in form II is significantly different from that in form II', suggesting that the change in orientation of PLP with temperature plays a role in the thermophilic enzymatic activity of StCGS.
Collapse
Affiliation(s)
- Dan Sato
- Department of Applied Biology, Kyoto Institute of Technology, Gosho Kaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Tomoo Shiba
- Department of Applied Biology, Kyoto Institute of Technology, Gosho Kaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Sae Mizuno
- Department of Applied Biology, Kyoto Institute of Technology, Gosho Kaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Ayaka Kawamura
- Department of Applied Biology, Kyoto Institute of Technology, Gosho Kaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Shoko Hanada
- Department of Applied Biology, Kyoto Institute of Technology, Gosho Kaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Tetsuya Yamada
- Department of Biofunctional Chemistry, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama 700-8530, Japan
| | - Mai Shinozaki
- Department of Biofunctional Chemistry, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama 700-8530, Japan
| | - Masahiko Yanagitani
- Department of Biofunctional Chemistry, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama 700-8530, Japan
| | - Takashi Tamura
- Department of Biofunctional Chemistry, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama 700-8530, Japan
| | - Kenji Inagaki
- Department of Biofunctional Chemistry, Okayama University, Tsushima-naka 1-1-1, Kita-ku, Okayama 700-8530, Japan
| | - Shigeharu Harada
- Department of Applied Biology, Kyoto Institute of Technology, Gosho Kaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| |
Collapse
|
5
|
Anufrieva NV, Faleev NG, Morozova EA, Bazhulina NP, Revtovich SV, Timofeev VP, Tkachev YV, Nikulin AD, Demidkina TV. The role of active site tyrosine 58 in Citrobacter freundii methionine γ-lyase. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:1220-8. [PMID: 25584856 DOI: 10.1016/j.bbapap.2014.12.027] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 12/29/2014] [Accepted: 12/30/2014] [Indexed: 10/24/2022]
Abstract
In the spatial structure of methionine γ-lyase (MGL, EC 4.4.1.11) from Citrobacter freundii, Tyr58 is located at H-bonding distance to the oxygen atom of the phosphate "handle" of pyridoxal 5'-phosphate (PLP). It was replaced for phenylalanine by site-directed mutagenesis. The X-ray structure of the mutant enzyme was determined at 1.96Å resolution. Comparison of spatial structures and absorption spectra of wild-type and mutant holoenzymes demonstrated that the replacement did not result in essential changes of the conformation of the active site Tyr58Phe MGL. The Kd value of PLP for Tyr58Phe MGL proved to be comparable to the Kd value for the wild-type enzyme. The replacement led to a decrease of catalytic efficiencies in both γ- and β-elimination reactions of about two orders of magnitude as compared to those for the wild-type enzyme. The rates of exchange of C-α- and C-β- protons of inhibitors in D2O catalyzed by the mutant form are comparable with those for the wild-type enzyme. Spectral data on the complexes of the mutant form with the substrates and inhibitors showed that the replacement led to a change of rate the limiting step of the physiological reaction. The results allowed us to conclude that Tyr58 is involved in an optimal positioning of the active site Lys210 at some stages of γ- and β-elimination reactions. This article is part of a Special Issue entitled: Cofactor-dependent proteins: evolution, chemical diversity and bio-applications.
Collapse
Affiliation(s)
- Natalya V Anufrieva
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, ul. Vavilova 32, Moscow 119991, Russia
| | - Nicolai G Faleev
- A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, ul. Vavilova 28, Moscow 117813, Russia
| | - Elena A Morozova
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, ul. Vavilova 32, Moscow 119991, Russia
| | - Natalia P Bazhulina
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, ul. Vavilova 32, Moscow 119991, Russia
| | - Svetlana V Revtovich
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, ul. Vavilova 32, Moscow 119991, Russia
| | - Vladimir P Timofeev
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, ul. Vavilova 32, Moscow 119991, Russia
| | - Yaroslav V Tkachev
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, ul. Vavilova 32, Moscow 119991, Russia
| | - Alexei D Nikulin
- Institute of Protein Research, Russian Academy of Sciences, ul. Institutskaya 4, Pushchino, Moscow Region 142290, Russia
| | - Tatyana V Demidkina
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, ul. Vavilova 32, Moscow 119991, Russia.
| |
Collapse
|
6
|
Astegno A, Allegrini A, Piccoli S, Giorgetti A, Dominici P. Role of active-site residues Tyr55 and Tyr114 in catalysis and substrate specificity of Corynebacterium diphtheriae C-S lyase. Proteins 2014; 83:78-90. [PMID: 25354840 DOI: 10.1002/prot.24707] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 09/29/2014] [Accepted: 10/18/2014] [Indexed: 11/07/2022]
Abstract
In recent years, there has been increased interest in bacterial methionine biosynthesis enzymes as antimicrobial targets because of their pivotal role in cell metabolism. C-S lyase from Corynebacterium diphtheriae is a pyridoxal 5'-phosphate-dependent enzyme in the transsulfuration pathway that catalyzes the α,β-elimination of sulfur-containing amino acids, such as L-cystathionine, to generate ammonia, pyruvate, and homocysteine, the immediate precursor of L-methionine. In order to gain deeper insight into the functional and dynamic properties of the enzyme, mutants of two highly conserved active-site residues, Y55F and Y114F, were characterized by UV-visible absorbance, fluorescence, and CD spectroscopy in the absence and presence of substrates and substrate analogs, as well as by steady-state kinetic studies. Substitution of Tyr55 with Phe apparently causes a 130-fold decrease in K(d)(PLP) at pH 8.5 providing evidence that Tyr55 plays a role in cofactor binding. Moreover, spectral data show that the mutant accumulates the external aldimine intermediate suggesting that the absence of interaction between the hydroxyl moiety and PLP-binding residue Lys222 causes a decrease in the rate of substrate deprotonation. Mutation of Tyr114 with Phe slightly influences hydrolysis of L-cystathionine, and causes a change in substrate specificity towards L-serine and O-acetyl-L-serine compared to the wild type enzyme. These findings, together with computational data, provide useful insights in the substrate specificity of C-S lyase, which seems to be regulated by active-site architecture and by the specific conformation in which substrates are bound, and will aid in development of inhibitors.
Collapse
Affiliation(s)
- Alessandra Astegno
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, Verona, Italy
| | | | | | | | | |
Collapse
|
7
|
A role for glutamate-333 of Saccharomyces cerevisiae cystathionine γ-lyase as a determinant of specificity. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1844:465-72. [PMID: 24291053 DOI: 10.1016/j.bbapap.2013.11.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 11/17/2013] [Accepted: 11/21/2013] [Indexed: 11/21/2022]
Abstract
Cystathionine γ-lyase (CGL) catalyzes the hydrolysis of l-cystathionine (l-Cth), producing l-cysteine (l-Cys), α-ketobutyrate and ammonia, in the second step of the reverse transsulfuration pathway, which converts l-homocysteine (l-Hcys) to l-Cys. Site-directed variants substituting residues E48 and E333 with alanine, aspartate and glutamine were characterized to probe the roles of these acidic residues, conserved in fungal and mammalian CGL sequences, in the active-site of CGL from Saccharomyces cerevisiae (yCGL). The pH optimum of variants containing the alanine or glutamine substitutions of E333 is increased by 0.4-1.2 pH units, likely due to repositioning of the cofactor and modification of the pKa of the pyridinium nitrogen. The pH profile of yCGL-E48A/E333A resembles that of Escherichia coli cystathionine β-lyase. The effect of substituting E48, E333 or both residues is the 1.3-3, 26-58 and 124-568-fold reduction, respectively, of the catalytic efficiency of l-Cth hydrolysis. The Km(l-Cth) of E333 substitution variants is increased ~17-fold, while Km(l-OAS) is within 2.5-fold of the wild-type enzyme, indicating that residue E333 interacts with the distal amine moiety of l-Cth, which is not present in the alternative substrate O-acetyl-l-serine. The catalytic efficiency of yCGL for α,γ-elimination of O-succinyl-l-homoserine (kcat/Km(l-OSHS)=7±2), which possesses a distal carboxylate, but lacks an amino group, is 300-fold lower than that of the physiological l-Cth substrate (kcat/Km(l-Cth)=2100±100) and 260-fold higher than that of l-Hcys (kcat/Km(l-Hcys)=0.027±0.005), which lacks both distal polar moieties. The results of this study suggest that the glutamate residue at position 333 is a determinant of specificity.
Collapse
|
8
|
Jaworski AF, Aitken SM. Exploration of the six tryptophan residues of Escherichia coli cystathionine β-lyase as probes of enzyme conformational change. Arch Biochem Biophys 2013; 538:138-44. [DOI: 10.1016/j.abb.2013.07.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 07/06/2013] [Accepted: 07/08/2013] [Indexed: 10/26/2022]
|
9
|
Exploration of structure–function relationships in Escherichia coli cystathionine γ-synthase and cystathionine β-lyase via chimeric constructs and site-specific substitutions. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:1044-53. [DOI: 10.1016/j.bbapap.2013.02.036] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 02/25/2013] [Accepted: 02/26/2013] [Indexed: 11/23/2022]
|
10
|
Morneau DJK, Jaworski AF, Aitken SM. Identification of cystathionine γ-synthase and threonine synthase from Cicer arietinum and Lens culinaris. Biochem Cell Biol 2013; 91:95-101. [PMID: 23527638 DOI: 10.1139/bcb-2012-0096] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
In plants, cystathionine γ-synthase (CGS) and threonine synthase (TS) compete for the branch-point metabolite O-phospho-L-homoserine. These enzymes are potential targets for metabolic engineering studies, aiming to alter the flux through the competing methionine and threonine biosynthetic pathways, with the goal of increasing methionine production. Although CGS and TS have been characterized in the model organisms Escherichia coli and Arabidopsis thaliana, little information is available on these enzymes in other, particularly plant, species. The functional CGS and TS coding sequences from the grain legumes Cicer arietinum (chickpea) and Lens culinaris (lentil) identified in this study share approximately 80% amino acid sequence identity with the corresponding sequences from Glycine max. At least 7 active-site residues of grain legume CGS and TS are conserved in the model bacterial enzymes, including the catalytic base. Putative processing sites that remove the targeting sequence and result in functional TS were identified in the target species.
Collapse
|