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Opperdoes FR, Záhonová K, Škodová-Sveráková I, Bučková B, Chmelová Ľ, Lukeš J, Yurchenko V. In silico prediction of the metabolism of Blastocrithidia nonstop, a trypanosomatid with non-canonical genetic code. BMC Genomics 2024; 25:184. [PMID: 38365628 PMCID: PMC10874023 DOI: 10.1186/s12864-024-10094-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Accepted: 02/06/2024] [Indexed: 02/18/2024] Open
Abstract
BACKGROUND Almost all extant organisms use the same, so-called canonical, genetic code with departures from it being very rare. Even more exceptional are the instances when a eukaryote with non-canonical code can be easily cultivated and has its whole genome and transcriptome sequenced. This is the case of Blastocrithidia nonstop, a trypanosomatid flagellate that reassigned all three stop codons to encode amino acids. RESULTS We in silico predicted the metabolism of B. nonstop and compared it with that of the well-studied human parasites Trypanosoma brucei and Leishmania major. The mapped mitochondrial, glycosomal and cytosolic metabolism contains all typical features of these diverse and important parasites. We also provided experimental validation for some of the predicted observations, concerning, specifically presence of glycosomes, cellular respiration, and assembly of the respiratory complexes. CONCLUSIONS In an unusual comparison of metabolism between a parasitic protist with a massively altered genetic code and its close relatives that rely on a canonical code we showed that the dramatic differences on the level of nucleic acids do not seem to be reflected in the metabolisms. Moreover, although the genome of B. nonstop is extremely AT-rich, we could not find any alterations of its pyrimidine synthesis pathway when compared to other trypanosomatids. Hence, we conclude that the dramatic alteration of the genetic code of B. nonstop has no significant repercussions on the metabolism of this flagellate.
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Affiliation(s)
- Fred R Opperdoes
- de Duve Institute, Université catholique de Louvain, Brussels, Belgium
| | - Kristína Záhonová
- Life Science Research Centre, Faculty of Science, University of Ostrava, Ostrava, Czechia
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czechia
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czechia
- Division of Infectious Diseases, Department of Medicine, University of Alberta, Edmonton, Canada
| | - Ingrid Škodová-Sveráková
- Life Science Research Centre, Faculty of Science, University of Ostrava, Ostrava, Czechia
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czechia
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
| | - Barbora Bučková
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
| | - Ľubomíra Chmelová
- Life Science Research Centre, Faculty of Science, University of Ostrava, Ostrava, Czechia
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czechia
- Faculty of Science, University of South Bohemia, České Budějovice, Czechia
| | - Vyacheslav Yurchenko
- Life Science Research Centre, Faculty of Science, University of Ostrava, Ostrava, Czechia.
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Kumar A, Wu G, Wu Z, Kumar N, Liu Z. Improved catalytic properties of a serine hydroxymethyl transferase from Idiomarina loihiensis by site directed mutagenesis. Int J Biol Macromol 2018; 117:1216-1223. [PMID: 29727646 DOI: 10.1016/j.ijbiomac.2018.05.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 04/05/2018] [Accepted: 05/01/2018] [Indexed: 11/17/2022]
Abstract
A novel glyA gene was screened from a marine bacterium, Idiomarina loihiensis encoding a thermo-stable serine hydroxymethyl transferase (SHMT; 418 AA; 45.4 kDa). The activities of wild type (WT) and mutants were analyzed against d-phenylserine using pyrodoxal-5-phosphate (PLP) as cofactor under optimized conditions. Based on homology modelling and molecular docking, several residues were found that may be able to improve the activity of WT-SHMT. Site directed mutagenesis was conducted. The activity and thermostability of the wild type SHMT was improved by two variants H61G and G132P, which showed a noteworthy change in the thermo-stability and activity as compared to WT. To investigate the mechanism of activity of mutants, we combined two residues into one mutant DUAL. WT showed the optimum activity at 50 °C, whereas H61G, G132P and DUAL had the temperature optima of 55, 60 and 60 °C, respectively. These mutants G132P, H61G and DUAL were quite stable at 45 and 55 °C as compared to WT. Dual mutant was relatively more stable at all tested pH(s) while WT loses its activity in alkaline pH(s). Kinetics studies indicated the 1.52, 2.42 and 4.54 folds increase in the kcat value of H61G, G132P and Dual mutants as compared to WT respectively. The molecular docking indicated that hydrophobic interactions are more prominent than hydrogen-bonding and had more influence on ligand binding and active site cavity. The molecular dynamics showed the changed RMSD values for ligand and formation of new hydrogen bonds, hydrophobic interaction which considerably increased the activity and thermo-stability of the mutant proteins as compared to WT. Thus, increased stabilities at higher temperatures and activities can be attributed to new hydrogen bonding, altered active site geometry and increased ligand interactions.
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Affiliation(s)
- Ashok Kumar
- College of Life Science and Technology, State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430 070, China; Department of Biotechnology and Bioinformatics, Jaypee University of Information Technology, Waknaghat, Solan, 172 234, Himachal Pradesh, India
| | - Gaobing Wu
- College of Life Science and Technology, State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430 070, China
| | - Zuo Wu
- College of Life Science and Technology, State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430 070, China
| | - Narendra Kumar
- Department of Biotechnology and Bioinformatics, Jaypee University of Information Technology, Waknaghat, Solan, 172 234, Himachal Pradesh, India
| | - Ziduo Liu
- College of Life Science and Technology, State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430 070, China.
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Nyíri K, Vértessy BG. Perturbation of genome integrity to fight pathogenic microorganisms. Biochim Biophys Acta Gen Subj 2016; 1861:3593-3612. [PMID: 27217086 DOI: 10.1016/j.bbagen.2016.05.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 05/05/2016] [Accepted: 05/18/2016] [Indexed: 10/21/2022]
Abstract
BACKGROUND Resistance against antibiotics is unfortunately still a major biomedical challenge for a wide range of pathogens responsible for potentially fatal diseases. SCOPE OF REVIEW In this study, we aim at providing a critical assessment of the recent advances in design and use of drugs targeting genome integrity by perturbation of thymidylate biosynthesis. MAJOR CONCLUSION We find that research efforts from several independent laboratories resulted in chemically highly distinct classes of inhibitors of key enzymes within the routes of thymidylate biosynthesis. The present article covers numerous studies describing perturbation of this metabolic pathway in some of the most challenging pathogens like Mycobacterium tuberculosis, Plasmodium falciparum, and Staphylococcus aureus. GENERAL SIGNIFICANCE Our comparative analysis allows a thorough summary of the current approaches to target thymidylate biosynthesis enzymes and also include an outlook suggesting novel ways of inhibitory strategies. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo.
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Affiliation(s)
- Kinga Nyíri
- Dept. Biotechnology, Budapest University of Technology and Economics, 4 Szent Gellért tér, Budapest HU 1111, Hungary; Institute of Enzymology, RCNS, Hungarian Academy of Sciences, 2 Magyar tudósok körútja, Budapest HU 1117, Hungary.
| | - Beáta G Vértessy
- Dept. Biotechnology, Budapest University of Technology and Economics, 4 Szent Gellért tér, Budapest HU 1111, Hungary; Institute of Enzymology, RCNS, Hungarian Academy of Sciences, 2 Magyar tudósok körútja, Budapest HU 1117, Hungary.
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4
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Pinthong C, Maenpuen S, Amornwatcharapong W, Yuthavong Y, Leartsakulpanich U, Chaiyen P. Distinct biochemical properties of human serine hydroxymethyltransferase compared with thePlasmodiumenzyme: implications for selective inhibition. FEBS J 2014; 281:2570-83. [DOI: 10.1111/febs.12803] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 03/25/2014] [Accepted: 03/31/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Chatchadaporn Pinthong
- Department of Biochemistry and Center of Excellence in Protein Structure and Function; Mahidol University; Bangkok Thailand
| | | | - Watcharee Amornwatcharapong
- Department of Biochemistry and Center of Excellence in Protein Structure and Function; Mahidol University; Bangkok Thailand
| | - Yongyuth Yuthavong
- National Center for Genetic Engineering and Biotechnology; National Science and Technology Development Agency; Pathumthani Thailand
| | - Ubolsree Leartsakulpanich
- National Center for Genetic Engineering and Biotechnology; National Science and Technology Development Agency; Pathumthani Thailand
| | - Pimchai Chaiyen
- Department of Biochemistry and Center of Excellence in Protein Structure and Function; Mahidol University; Bangkok Thailand
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Zhang Y, Sun K, Sandoval FJ, Santiago K, Roje S. One-carbon metabolism in plants: characterization of a plastid serine hydroxymethyltransferase. Biochem J 2010; 430:97-105. [PMID: 20518745 DOI: 10.1042/bj20100566] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
SHMT (serine hydroxymethyltransferase; EC 2.1.2.1) catalyses reversible hydroxymethyl group transfer from serine to H4PteGlun (tetrahydrofolate), yielding glycine and 5,10-methylenetetrahydrofolate. In plastids, SHMTs are thought to catalytically direct the hydroxymethyl moiety of serine into the metabolic network of H4PteGlun-bound one-carbon units. Genes encoding putative plastid SHMTs were found in the genomes of various plant species. SHMT activity was detected in chloroplasts in pea (Pisum sativum) and barley (Hordeum vulgare), suggesting that plastid SHMTs exist in all flowering plants. The Arabidopsis thaliana genome encodes one putative plastid SHMT (AtSHMT3). Its cDNA was cloned by reverse transcription-PCR and the encoded recombinant protein was produced in Escherichia coli. Evidence that AtSHMT3 is targeted to plastids was found by confocal microscopy of A. thaliana protoplasts transformed with proteins fused to enhanced green fluorescent protein. Characterization of recombinant AtSHMT3 revealed that substrate affinity for and the catalytic efficiency of H4PteGlu1-8 increase with n, and that H4PteGlu1-8 inhibit AtSHMT3. 5-Methyltetrahydrofolate and 5-formyltetrahydrofolate with one and five glutamate residues inhibited AtSHMT3-catalysed hydroxymethyl group transfer from serine to H4PteGlu6, with the pentaglutamylated inhibitors being more effective. Calculations revealed inhibition with 5-methyltetrahydrofolate or 5-formyltetrahydrofolate resulting in little reduction in AtSHMT3 activity under folate concentrations estimated for plastids.
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Affiliation(s)
- Yi Zhang
- Washington State University, Pullman, 99164, USA
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Maenpuen S, Sopitthummakhun K, Yuthavong Y, Chaiyen P, Leartsakulpanich U. Characterization of Plasmodium falciparum serine hydroxymethyltransferase-A potential antimalarial target. Mol Biochem Parasitol 2009; 168:63-73. [PMID: 19591881 DOI: 10.1016/j.molbiopara.2009.06.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2009] [Revised: 06/02/2009] [Accepted: 06/25/2009] [Indexed: 10/20/2022]
Abstract
Serine hydroxymethyltransferase (SHMT) is a ubiquitous enzyme required for folate recycling and dTMP synthesis. A cDNA encoding Plasmodium falciparum (Pf) SHMT was expressed as a hexa-histidine tagged protein in Escherichia coli BL21-CodonPlus (DE3)-RIL. The protein was purified and the process yielded 3.6 mg protein/l cell culture. Recombinant His(6)-tagged PfSHMT exhibits a visible spectrum characteristic of pyridoxal-5'-phosphate enzyme and catalyzes the reversible conversion of l-serine and tetrahydrofolate (H(4)folate) to glycine and 5,10-methylenetetrahydrofolate (CH(2)-H(4)folate). Steady-state kinetics study indicates that His(6)-tagged PfSHMT catalyzes the reaction by a ternary-complex mechanism. The sequence of substrate binding to the enzyme was also examined by glycine product inhibition. A striking property that is unique for His(6)-tagged PfSHMT is the ability to use D-serine as a substrate in the folate-dependent serine-glycine conversion. Kinetic data in combination with expression result support the proposal of SHMT reaction being a regulatory step for dTMP cycle. This finding suggests that PfSHMT can be a potential target for antimalarial chemotherapy.
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Affiliation(s)
- Somchart Maenpuen
- Department of Biochemistry and Center for Excellence in Protein Structure & Function, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok, Thailand
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Vatsyayan R, Roy U. Molecular cloning and biochemical characterization of Leishmania donovani serine hydroxymethyltransferase. Protein Expr Purif 2006; 52:433-40. [PMID: 17142057 DOI: 10.1016/j.pep.2006.10.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2006] [Revised: 10/16/2006] [Accepted: 10/18/2006] [Indexed: 10/24/2022]
Abstract
Serine hydroxymethyltransferase (SHMT) catalyzes the inter conversion of serine and tetrahydrofolate (H(4)-folate) to form glycine and 5,10-methylene H(4)-folate and generates one-carbon fragments for the synthesis of nucleotides, methionine, thymidylate, choline, etc. In spite of being an indispensable enzyme of the thymidylate cycle, SHMT in Leishmania donovani remains uncharacterized. The study of L. donovani SHMT (ldSHMT) becomes important as this gene is preferentially expressed in the amastigote stage of parasite, which resides in human macrophages. Here we report cloning, expression and purification of a catalytically active ldSHMT. The homogeneity of recombinant protein was analyzed by denaturing gel electrophoresis and protein was found to be 95% pure having yield of 1mg/l. The recombinant protein is a tetramer of 216kDa as evidenced by gel filtration chromatography and uses serine and tetrahydrofolate as substrates with Km of 1.6 and 2.4mM, respectively. Further biochemical studies revealed that pH optimum of ldSHMT is 7.8 and enzyme is thermally stable up to 45 degrees C. ldSHMT was found sensitive towards denaturants as manifested by loss of enzyme activity at the concentration of 1M urea or 0.25M guanidine hydrochloride. This is the first report of purification and characterization of recombinant SHMT from any protozoan source. Studies on recombinant ldSHMT will help in evaluating this enzyme as potential drug target.
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Affiliation(s)
- Rit Vatsyayan
- Biochemistry Division, Central Drug Research Institute, Lucknow 226001, India
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Mukherjee M, Sievers SA, Brown MT, Johnson PJ. Identification and biochemical characterization of serine hydroxymethyl transferase in the hydrogenosome of Trichomonas vaginalis. EUKARYOTIC CELL 2006; 5:2072-8. [PMID: 16980404 PMCID: PMC1694819 DOI: 10.1128/ec.00249-06] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Serine hydroxymethyl transferase (SHMT) is a pyridoxal phosphate (PLP)-dependent enzyme that catalyzes the reversible conversion of serine and tetrahydrofolate to glycine and methylenetetrahydrofolate. We have identified a single gene encoding SHMT in the genome of Trichomonas vaginalis, an amitochondriate, deep-branching unicellular protist. The protein possesses a putative N-terminal hydrogenosomal presequence and was shown to localize to hydrogensomes by immunofluorescence analysis, providing evidence of amino acid metabolism in this unusual organelle. In contrast to the tetrameric SHMT that exists in the mammalian host, we found that the T. vaginalis SHMT is a homodimer, as found in prokaryotes. All examined SHMT contain an 8-amino-acid conserved sequence, VTTTTHKT, containing the active-site lysyl residue (Lys 251 in TvSHMT) that forms an internal aldimine with PLP. We mutated this Lys residue to Arg and Gln and examined structural and catalytic properties of the wild-type and mutant enzymes in comparison to that reported for the mammalian protein. The oligomeric structure of the mutant K251R and K251Q TvSHMT was not affected, in contrast to that observed for comparable mutations in the mammalian enzyme. Likewise, contrary to that observed for mammalian SHMT, the catalytic activity of K251R TvSHMT was unaffected in the presence of PLP. The K251Q TvSHMT, however, was found to be inactive. These studies indicate that the active site of the parasite enzyme is distinct from its prokaryotic and eukaryotic counterparts and identify TvSHMT as a potential drug target.
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Affiliation(s)
- Mandira Mukherjee
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, 609 Charles E. Young Drive East, Los Angeles, CA 90095-1489, USA
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Gagnon D, Foucher A, Girard I, Ouellette M. Stage specific gene expression and cellular localization of two isoforms of the serine hydroxymethyltransferase in the protozoan parasite Leishmania. Mol Biochem Parasitol 2006; 150:63-71. [PMID: 16876889 DOI: 10.1016/j.molbiopara.2006.06.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Revised: 06/22/2006] [Accepted: 06/23/2006] [Indexed: 11/20/2022]
Abstract
Serine hydroxymethyltransferase (SHMT) catalyses the reversible conversion of serine and tetrahydrofolate to glycine and methylene-tetrahydrofolate. The recent completion of the genome sequence of Leishmania major revealed the presence of two genes coding for two isoforms of this protein. In silico analysis showed that one isoform had an extension at its N-terminus and was predicted to localize to the mitochondrion. The situation is different in other kinetoplastid parasites with only one SHMT encoding gene in Trypanosoma cruzi and no SHMT encoding gene in Trypanosoma brucei. The two L. major SHMT genes were cloned in frame with the green fluorescent protein and the resulting fusion proteins showed differential localization: the short form (SHMT-S) was found in the cytosol while the long one (SHMT-L) was found in an organelle that has hallmarks of the parasite mitochondrion. Indeed, SHMT-L had a similar cellular fractionation pattern as the mitochondrial HSP60 as determined by digitonin fractionation. Both SHMT-S and SHMT-L genes were expressed preferentially in the amastigote stage of the parasite and the RNA levels of SHMT-L could be modulated by glycine, serine, and folate. Overexpression of SHMT-S increased resistance to the antifolate methotrexate and to a lower level to the inhibitor thiosemicarbazide in a rich folate containing medium. These findings suggest that folate metabolism is compartmentalised in Leishmania and that SHMT RNA levels are responsive to environmental conditions.
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Affiliation(s)
- Dominic Gagnon
- Centre de Recherche en Infectiologie du Centre de recherche du CHUL, Division de Microbiologie, Faculté de Médecine, Université Laval, Québec, Canada
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Chaturvedi S, Bhakuni V. Unusual structural, functional, and stability properties of serine hydroxymethyltransferase from Mycobacterium tuberculosis. J Biol Chem 2003; 278:40793-805. [PMID: 12913008 DOI: 10.1074/jbc.m306192200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
From the genome analysis of the Mycobacterium tuberculosis two putative genes namely GlyA and GlyA2 have been proposed to encode for the enzyme serine hydroxymethyltransferase. We have cloned, overexpressed, and purified to homogeneity their respective protein products, serine hydroxymethyltransferase, SHM1 and SHM2. The recombinant SHM1 and SHM2 exist as homodimers of molecular mass about 90 kDa under physiological conditions, however, SHM2 has more compact conformation and higher thermal stability than SHM1. The most interesting structural observation was that the SHM1 contains 1 mol of pyridoxal 5'-phosphate (PLP)/mol of enzyme dimer. This is the first report of such a unique stoichiometry of PLP and enzyme dimer for SHMT. The SHM2 contains 2 mol of PLP/mol of enzyme dimer, which is the usual stoichiometry reported for SHMT. Functionally both the recombinant enzymes showed catalysis of reversible interconversion of serine and glycine and aldol cleavage of a 3-hydroxyamino acid. However, unlike SHMT from other sources both SHM1 and SHM2 do not undergo half-transamination reaction with d-alanine resulting in formation of apoenzyme but l-cysteine removed the prosthetic group, PLP, from both the recombinant enzymes leaving the respective inactive apoenzymes. Comparative structural studies on the two enzymes showed that the SHM1 is resistant to alkaline denaturation up to pH 10.5, whereas the native SHM2 dimer dissociates into monomer at pH 9. Urea- and guanidinium chloride-induced two-step unfolding of SHM1 and SHM2 with the first step being dissociation of dimer into apomonomer at low denaturant concentrations followed by unfolding of the stabilized monomer at higher denaturant concentrations.
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Affiliation(s)
- Sarita Chaturvedi
- Division of Molecular and Structural Biology, Central Drug Research Institute, Lucknow 226 001, India
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Ouellette M, Drummelsmith J, El-Fadili A, Kündig C, Richard D, Roy G. Pterin transport and metabolism in Leishmania and related trypanosomatid parasites. Int J Parasitol 2002; 32:385-98. [PMID: 11849635 DOI: 10.1016/s0020-7519(01)00346-0] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The folate metabolic pathway has been exploited successfully for the development of antimicrobial and antineoplasic agents. Inhibitors of this pathway, however, are not useful against Leishmania and other trypanosomatids. Work on the mechanism of methotrexate resistance in Leishmania has dramatically increased our understanding of folate and pterin metabolism in this organism. The metabolic and cellular functions of the reduced form of folates and pterins are beginning to be established and this work has led to several unexpected findings. Moreover, the currently ongoing sequencing efforts on trypanosomatid genomes are suggesting the presence of several gene products that are likely to require folates and pterins. A number of the properties of folate and pterin metabolism are unique suggesting that these pathways are valid and worthwhile targets for drug development.
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Affiliation(s)
- Marc Ouellette
- Centre de recherche en Infectiologie du CHUL, 2705, boul. Laurier, QC, Sainte-Foy, Canada GIV 4G2.
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Capelluto DG, Hellman U, Cazzulo JJ, Cannata JJ. Purification and some properties of serine hydroxymethyltransferase from Trypanosoma cruzi. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:712-9. [PMID: 10651807 DOI: 10.1046/j.1432-1327.2000.01047.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A single form of serine hydroxymethyltransferase (SHMT) was detected in epimastigotes of Trypanosoma cruzi, in contrast to the three isoforms of the enzyme characterized from another trypanosomatid, Crithidia fasciculata [Capelluto D.G.S., Hellman U., Cazzulo J.J. & Cannata J.J.B. (1999) Mol. Biochem. Parasitol. 98, 187-201]. The T. cruzi SHMT was found to be highly unstable in crude extracts. In the presence of the cysteine proteinase inhibitors N-alpha-p-tosyl-L-lysine chloromethyl ketone and Ltrans-3-carboxyoxiran-2-carbonyl-L-leucylagmatine, however, the enzyme could be purified to homogeneity. Digitonin treatment of intact cells suggested that the enzyme is cytosolic. T. cruzi SHMT presents a monomeric structure shown by the apparent molecular masses of 69 kDa (native) and 55 kDa (subunit) determined by Sephadex G-200 gel filtration and SDS/PAGE, respectively. This is in contrast to the tetrameric SHMTs described in C. fasciculata and other eukaryotes. The enzyme was pyridoxal phosphate-dependent after L-cysteine and hydroxylamine treatments and it was strongly inhibited by the substrate analog folate, which was competitive towards tetrahydrofolate and noncompetitive towards L-serine. Partial sequencing of tryptic internal peptides of the enzyme indicate considerable similarity with other SHMTs, particularly from those of plant origin.
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Affiliation(s)
- D G Capelluto
- Centro de Investigaciones Bioenergéticas, Facultad de Medicina-CONICET, Universidad de Buenos Aires, Argentina
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