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Yadav J, Singh H, Pal SK, Das S, Srivastava VK, Jyoti A, Sharma V, Kumar S, Kaushik S. Exploring the molecular interaction of Pheniramine with Enterococcus faecalis Homoserine Kinase: In-silico and in vitro studies. J Mol Recognit 2022; 35:e2979. [PMID: 35642097 DOI: 10.1002/jmr.2979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 05/03/2022] [Accepted: 05/26/2022] [Indexed: 11/07/2022]
Abstract
Infections caused by the bacteria Enterococcus faecalis (also known as E. faecalis) are common in hospitals. This bacterium is resistant to a wide range of medicines and causes a variety of nosocomial infections. An increase in the number of infections caused by multidrug-resistant (MDR) bacteria is causing substantial economic and health issues around the world. Consequently, new therapeutic techniques to tackle the growing threat of E. faecalis infections must be developed as soon as possible. In this regard, we have targeted a protein that is regarded to be critical for the survival of bacteria in this experiment. Homoserine kinase (HSK) is a threonine metabolism enzyme that belongs to the GHMP kinase superfamily. It is a crucial enzyme in threonine metabolism. This enzyme is responsible for a critical step in the threonine biosynthesis pathway. Given the important function that E. faecalis Homoserine Kinase (ESK) plays in bacterial metabolism, we proposed that E. faecalis HSK be cloned, overexpressed, purified, and subjected to structural analyses using homology modelling. In addition, we have reported on the model's molecular docking and Molecular Dynamic Stimulation (MD Stimulation) investigations to validate the results of the docking experiments. The results were promising. In silico investigations came up with the conclusion: pheniramine has good binding affinity for the E. faecalis HSK.
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Affiliation(s)
- Jyoti Yadav
- Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur, India
| | - Harpreet Singh
- Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur, India
| | - Sudhir Kumar Pal
- Centre for Bioseparation Technology, VIT University, Vellore, India
| | - Satyajeet Das
- Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur, India
| | | | - Anupam Jyoti
- Department of Biotechnology, University Institute of Biotechnology, Chandigarh University, Chandigarh, India
| | - Vinay Sharma
- Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur, India
| | - Sanjit Kumar
- Centre for Bioseparation Technology, VIT University, Vellore, India
| | - Sanket Kaushik
- Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur, India
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Functional analysis of the genes encoding diaminopropionate ammonia lyase in Escherichia coli and Salmonella enterica serovar Typhimurium. J Bacteriol 2012; 194:5604-12. [PMID: 22904288 DOI: 10.1128/jb.01362-12] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Diaminopropionate ammonia lyase (DAPAL) is a pyridoxal-5'phosphate (PLP)-dependent enzyme that catalyzes the conversion of diaminopropionate (DAP) to pyruvate and ammonia and plays an important role in cell metabolism. We have investigated the role of the ygeX gene of Escherichia coli K-12 and its ortholog, STM1002, in Salmonella enterica serovar Typhimurium LT2, presumed to encode DAPAL, in the growth kinetics of the bacteria. While Salmonella Typhimurium LT2 could grow on dl-DAP as a sole carbon source, the wild-type E. coli K-12 strain exhibited only marginal growth on dl-DAP, suggesting that DAPAL is functional in S. Typhimurium. The expression of ygeX in E. coli was low as detected by reverse transcriptase PCR (RT-PCR), consistent with the poor growth of E. coli on dl-DAP. Strains of S. Typhimurium and E. coli with STM1002 and ygeX, respectively, deleted showed loss of growth on dl-DAP, confirming that STM1002 (ygeX) is the locus encoding DAPAL. Interestingly, the presence of dl-DAP caused a growth inhibition of the wild-type E. coli strain as well as the knockout strains of S. Typhimurium and E. coli in minimal glucose/glycerol medium. Inhibition by dl-DAP was rescued by transforming the strains with plasmids containing the STM1002 (ygeX) gene encoding DAPAL or supplementing the medium with Casamino Acids. Growth restoration studies using media lacking specific amino acid supplements suggested that growth inhibition by dl-DAP in the absence of DAPAL is associated with auxotrophy related to the inhibition of the enzymes involved in the biosynthetic pathways of pyruvate and aspartate and the amino acids derived from them.
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Morneau DJK, Abouassaf E, Skanes JE, Aitken SM. Development of a continuous assay and steady-state characterization of Escherichia coli threonine synthase. Anal Biochem 2012; 423:78-85. [PMID: 22289691 DOI: 10.1016/j.ab.2012.01.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 01/02/2012] [Accepted: 01/09/2012] [Indexed: 10/14/2022]
Abstract
Threonine synthase (TS) catalyzes the hydrolysis of O-phospho-L-homoserine (OPHS) to produce L-threonine (L-Thr) and inorganic phosphate. Here, we report a simplified purification protocol for the OPHS substrate and a continuous, coupled-coupled, spectrophotometric TS assay. The sequential actions of threonine deaminase (TD) and hydroxyisocaproate dehydrogenase (HO-HxoDH) convert the L-Thr product of TS to α-ketobutyrate (α-KB) and then to 2-hydroxybutyrate, respectively, and are monitored as the decrease in absorbance at 340 nm resulting from the concomitant oxidation of β-nicotinamide adenine dinucleotide (NADH) to NAD(+) by HO-HxoDH. The effect of pH on the activities of Escherichia coli TD and Lactobacillus delbrueckii HO-HxoDH was determined to establish this continuous assay as suitable for steady-state characterization and to facilitate the optimization of coupling enzyme concentrations under different assay conditions to enable studies of TS across phyla. To validate this assay, TS from E. coli was characterized. The kinetic parameters (k(cat)=4s(-1) and K(m)=0.34 mM) and the pH optimum of 8.7, determined using the continuous assay, are consistent with values reported for this enzyme based on the discontinuous malachite green assay. The k(cat)/K(m)(OPHS) versus pH profile of E. coli TS is bell-shaped, and the apparent pK(a) values for the acidic and basic limbs are 7.1 and 10.4, respectively.
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Ning C, Gest H. Regulation of L-isoleucine biosynthesis in the photosynthetic bacterium rhodospirillum rubrum. Proc Natl Acad Sci U S A 2010; 56:1823-7. [PMID: 16591426 PMCID: PMC220189 DOI: 10.1073/pnas.56.6.1823] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- C Ning
- ADOLPHUS BUSCH III LABORATORY OF MOLECULAR BIOLOGY, WASHINGTON UNIVERSITY, ST. LOUIS, MISSOURI
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ANDERSSON-KOTTÖ IRMA, EHRENSVÄRD GÖSTA. THE INTEGRATIVE EFFECT OF SOME GENETICAL AND EXOGENOUS FACTORS UPON AMINO ACID FORMATION IN NEUROSPORA CRASSA. Hereditas 2009. [DOI: 10.1111/j.1601-5223.1963.tb01893.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Stadtman ER. Allosteric regulation of enzyme activity. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 28:41-154. [PMID: 5334065 DOI: 10.1002/9780470122730.ch2] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Ames BN, Garry B. COORDINATE REPRESSION OF THE SYNTHESIS OF FOUR HISTIDINE BIOSYNTHETIC ENZYMES BY HISTIDINE. Proc Natl Acad Sci U S A 2006; 45:1453-61. [PMID: 16590526 PMCID: PMC222738 DOI: 10.1073/pnas.45.10.1453] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- B N Ames
- NATIONAL INSTITUTE OF ARTHRITIS AND METABOLIC DISEASES, BETHESDA, MARYLAND
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Garrido-Franco M, Ehlert S, Messerschmidt A, Marinkovic' S, Huber R, Laber B, Bourenkov GP, Clausen T. Structure and function of threonine synthase from yeast. J Biol Chem 2002; 277:12396-405. [PMID: 11756443 DOI: 10.1074/jbc.m108734200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Threonine synthase catalyzes the final step of threonine biosynthesis, the pyridoxal 5'-phosphate (PLP)-dependent conversion of O-phosphohomoserine into threonine and inorganic phosphate. Threonine is an essential nutrient for mammals, and its biosynthetic machinery is restricted to bacteria, plants, and fungi; therefore, threonine synthase represents an interesting pharmaceutical target. The crystal structure of threonine synthase from Saccharomyces cerevisiae has been solved at 2.7 A resolution using multiwavelength anomalous diffraction. The structure reveals a monomer as active unit, which is subdivided into three distinct domains: a small N-terminal domain, a PLP-binding domain that covalently anchors the cofactor and a so-called large domain, which contains the main of the protein body. All three domains show the typical open alpha/beta architecture. The cofactor is bound at the interface of all three domains, buried deeply within a wide canyon that penetrates the whole molecule. Based on structural alignments with related enzymes, an enzyme-substrate complex was modeled into the active site of yeast threonine synthase, which revealed essentials for substrate binding and catalysis. Furthermore, the comparison with related enzymes of the beta-family of PLP-dependent enzymes indicated structural determinants of the oligomeric state and thus rationalized for the first time how a PLP enzyme acts in monomeric form.
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Affiliation(s)
- Marta Garrido-Franco
- Max-Planck-Institut für Biochemie, Abteilung Strukturforschung, am Klopferspitz 18A, Martinsried 82152, Germany
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Zhou T, Daugherty M, Grishin NV, Osterman AL, Zhang H. Structure and mechanism of homoserine kinase: prototype for the GHMP kinase superfamily. Structure 2000; 8:1247-57. [PMID: 11188689 DOI: 10.1016/s0969-2126(00)00533-5] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Homoserine kinase (HSK) catalyzes an important step in the threonine biosynthesis pathway. It belongs to a large yet unique class of small metabolite kinases, the GHMP kinase superfamily. Members in the GHMP superfamily participate in several essential metabolic pathways, such as amino acid biosynthesis, galactose metabolism, and the mevalonate pathway. RESULTS The crystal structure of HSK and its complex with ADP reveal a novel nucleotide binding fold. The N-terminal domain contains an unusual left-handed betaalphabeta unit, while the C-terminal domain has a central alpha-beta plait fold with an insertion of four helices. The phosphate binding loop in HSK is distinct from the classical P loops found in many ATP/GTP binding proteins. The bound ADP molecule adopts a rare syn conformation and is in the opposite orientation from those bound to the P loop-containing proteins. Inspection of the substrate binding cavity indicates several amino acid residues that are likely to be involved in substrate binding and catalysis. CONCLUSIONS The crystal structure of HSK is the first representative in the GHMP superfamily to have determined structure. It provides insight into the structure and nucleotide binding mechanism of not only the HSK family but also a variety of enzymes in the GHMP superfamily. Such enzymes include galactokinases, mevalonate kinases, phosphomevalonate kinases, mevalonate pyrophosphate decarboxylases, and several proteins of yet unknown functions.
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Affiliation(s)
- T Zhou
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75390, USA
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GIBSON KD, NEUBERGER A, TAIT GH. Studies on the biosynthesis of prophyrin and bacteriochlorophyll by Rhodoseudomonas spheroides. 3. The effect of threonine on the biosynthesis of homoserine and methionine. Biochem J 1998; 84:483-90. [PMID: 13898424 PMCID: PMC1243701 DOI: 10.1042/bj0840483] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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FRY BA. THE RELATIONSHIP BETWEEN THE COMPOSITION OF THE ENVIRONMENT AND THE CONTROL OF BIOSYNTHESIS IN BACTERIA. Proc Nutr Soc 1996; 23:170-88. [PMID: 14189105 DOI: 10.1079/pns19640030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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WALTER C, FRIEDEN E. THE PREVALENCE AND SIGNIFICANCE OF THE PRODUCT INHIBITION OF ENZYMES. ACTA ACUST UNITED AC 1996; 25:167-274. [PMID: 14149677 DOI: 10.1002/9780470122709.ch4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
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Abstract
Pizer, Lewis I. (University of Pennsylvania, Philadelphia), and Mary L. Potochny. Nutritional and regulatory aspects of serine metabolism in Escherichia coli. J. Bacteriol. 88:611-619. 1964.-Growth studies with a serine auxotroph have demonstrated a relationship between the serine supplied and the extent of growth, which closely agrees with the value calculated from the reported chemical composition of Escherichia coli. Serine could be replaced by glycine and, to a limited extent, by l-threonine. Both exogenous serine and glycine regulate their own endogenous synthesis from glucose or fructose. The inhibition of endogenous synthesis of both amino acids by serine was greater than 90% with both carbon sources. Greater amounts of exogenous glycine were utilized for cell synthesis when fructose was the carbon source. Growth conditions affected the levels of phosphoglycerate dehydrogenase found in cell-free extracts. The highest levels were found in glucose-grown cells and the lowest in cells grown in a medium augmented with l-threonine, l-methionine, l-leucine, and dl-isoleucine. The levels of serine phosphate phosphatase were not altered by changes in growth conditions.
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Curien G, Dumas R, Ravanel S, Douce R. Characterization of an Arabidopsis thaliana cDNA encoding an S-adenosylmethionine-sensitive threonine synthase. Threonine synthase from higher plants. FEBS Lett 1996; 390:85-90. [PMID: 8706836 DOI: 10.1016/0014-5793(96)00633-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
An Arabidopsis thaliana cDNA encoding an S-adenosylmethionine-sensitive threonine synthase (EC 4.2.99.2) has been isolated by functional complementation of an Escherichia coli mutant devoid of threonine synthase activity. Threonine synthase from A. thaliana was shown to be synthesized with a transit peptide. The recombinant protein is activated by S-adenosylmethionine in the same range as the plant threonine synthase and evidence is presented for an involvement of the N-terminal part of the mature enzyme in the sensitivity to S-adenosylmethionine.
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Affiliation(s)
- G Curien
- Laboratoire Mixte, Centre National de la Recherche Scientifique/Rhône-Poulenc UMR-41, Lyon, France
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Colón GE, Jetten MS, Nguyen TT, Gubler ME, Follettie MT, Sinskey AJ, Stephanopoulos G. Effect of inducible thrB expression on amino acid production in Corynebacterium lactofermentum ATCC 21799. Appl Environ Microbiol 1995; 61:74-8. [PMID: 7887627 PMCID: PMC167261 DOI: 10.1128/aem.61.1.74-78.1995] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Amplification of the operon homdr-thrB encoding a feedback-insensitive homoserine dehydrogenase and a wild-type homoserine kinase in a Corynebacterium lactofermentum lysine-producing strain resulted in both homoserine and threonine accumulation, with some residual lysine production. A plasmid enabling separate transcriptional control of each gene was constructed to determine the effect of various enzyme activity ratios on metabolite accumulation. By increasing the activity of homoserine kinase relative to homoserine dehydrogenase activity, homoserine accumulation in the medium was essentially eliminated and the final threonine titer was increased by about 120%. Furthermore, a fortuitous result of the cloning strategy was an unexplained increase in homoserine dehydrogenase activity. This resulted in a further decrease in lysine production along with a concomitant increase in threonine accumulation.
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Affiliation(s)
- G E Colón
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge 02139
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Mannhaupt G, Pohlenz HD, Seefluth AK, Pilz U, Feldmann H. Yeast homoserine kinase. Characteristics of the corresponding gene, THR1, and the purified enzyme, and evolutionary relationships with other enzymes of threonine metabolism. EUROPEAN JOURNAL OF BIOCHEMISTRY 1990; 191:115-22. [PMID: 2165904 DOI: 10.1111/j.1432-1033.1990.tb19100.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
THR1, the gene from Saccharomyces cerevisiae, encoding homoserine kinase, one of the threonine biosynthetic enzymes, has been cloned by complementation. The nucleotide sequence of a 3.1-kb region carrying this gene reveals an open reading frame of 356 codons, corresponding to about 40 kDa for the encoded protein. The presence of three canonical GCN4 regulatory sequences in the upstream flanking region suggests that the expression of THR1 is under the general amino acid control. In parallel, the enzyme was purified by four consecutive column chromatographies, monitoring homoserine kinase activity. In SDS gel electrophoresis, homoserine kinase migrates like a 40-kDa protein; the native enzyme appears to be a homodimer. The sequence of the first 15 NH2-terminal amino acids, as determined by automated Edman degradation, is in accordance with the amino acid sequence deduced from the nucleotide sequence. Computer-assisted comparison of the yeast enzyme with the corresponding activities from bacterial sources showed that several segments among these proteins are highly conserved. Furthermore, the observed homology patterns suggest that the ancestral sequences might have been composed from separate (functional) domains. A block of very similar amino acids is found in the homoserine kinases towards the carboxy terminus that is also present in many other proteins involved in threonine (or serine) metabolism; this motif, therefore, may represent the binding site for the hydroxyamino acids. Limited similarity was detected between a motif conserved among the homoserine kinases and consensus sequences found in other mono- or dinucleotide-binding proteins.
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Affiliation(s)
- G Mannhaupt
- Institut für Physiologische Chemie, Physikalische Biochemie und Zellbiologie, Universität München, Federal Republic of Germany
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Finkelnburg B, Klemme JH. Homoserine kinase from the phototrophic bacteriumRhodospirillum rubrumis not sensitive to feedback inhibition by l-threonine. FEMS Microbiol Lett 1987. [DOI: 10.1111/j.1574-6968.1987.tb02522.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Aarnes H. Regulation of threonine biosynthesis in barley seedlings (Hordeum vulgare L.). PLANTA 1978; 140:185-192. [PMID: 24414476 DOI: 10.1007/bf00384919] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/1978] [Accepted: 01/30/1978] [Indexed: 06/03/2023]
Abstract
Homoserine kinase was purified 700-fold by fractional ammonium sulfate precipitation, heat treatment, CM-Sephadex C-50 and DEAE-Sephadex A-50 ion exchange chromatography, and Sephadex G-100 gel filtration. The reaction products O-phosphohomoserine and ADP were the only compounds which caused considerable inhibition of homoserine kinase activity. Product inhibition studies showed non-competitive inhibition between ATP and O-phosphohomoserine and between homoserine and O-phosphohomoserine, and competitive inhibition between ATP and ADP. ADP showed non-competitive inhibition versus homoserine at suboptimal concentrations of ATP. At saturating concentrations of ATP no effect of ADP was observed. The homoserine kinase activity was negligible in the absence of K(+) and the Km value for K(+) was observed to be 4.3 mmol l(-1). A non-competitive pattern was observed with respect to the substrates homoserine and ATP. Threonine synthase in the first green leaf of 6-day-old barley seedlings was partially purified 15-fold by ammonium sulfate fractionation and Sephadex G-100 gel chromatography. Threonine synthase was shown to require pyridoxal 5'-phosphate as coenzyme for optimum activity and the enzyme was strongly activated by S-adenosyl-L-methionine. The optimum pH for threonine synthase activity was 7 to 8.
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Affiliation(s)
- H Aarnes
- Botanical Laboratory, University of Oslo, Blindern, P.O. Box 1045, Oslo 3, Norway
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Johnson EJ, Cohen GN, Saint-Girons I. Threonyl-transfer ribonucleic acid synthetase and the regulation of the threonine operon in Escherichia coli. J Bacteriol 1977; 129:66-70. [PMID: 318654 PMCID: PMC234895 DOI: 10.1128/jb.129.1.66-70.1977] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Two threonine-requiring mutants with derepressed expression of the threonine operon were isolated from an Escherichia coli K-12 strain containing two copies of the thr operon. One of them carries a leaky mutation in ilvA (the structural gene for threonine deaminase), which creates an isoleucine limitation and therefore derepression of the thr operon. In the second mutant, the enzymes of the thr operon were not repressed by threonine plus isoleucine; the threonyl-transfer ribonucleic acid(tRNA) synthetase from this mutant shows an apparent Km for threonine 200-fold higher than that of the parental strain. The gene, called thrS, coding for threonyl-tRNA synthetase was located around 30 min on the E. coli map. The regulatory properties of this mutant imply the involvement of charged threonyl-tRNA or threonyl-tRNA synthetase in the regulation of the thr operon.
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Sugimoto Y, Nakatani K, Shirakashi T, Ohmori H, Toraya T, Fukui S. Mechanism of inhibition of Chromatium D growth by L-methionine. Regulation of L-threonine biosynthesis by the intracellular level of S-adenosylmethionine. Biochim Biophys Acta Gen Subj 1976; 437:333-44. [PMID: 8102 DOI: 10.1016/0304-4165(76)90003-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
(1) An unusual accumulation of S-adenosyl-L-methionine in Chromatium D was associated with a marked growth inhibition by L-methionine. The inhibition was overcome by L-isoleucine, L-leucine, L-phyenylalanine, L-threonine, L-valine and putrescien. Based on their effects, these compounds are classified into 3 types. (2) L-Isoleucine, L-leucine, L-phyenylalanine and L-valine (Type I) inhibited the L-methionine uptake and consequently prevented the bacterium from the unusual accumulation of S-adenosyl-L-methionine even in the presence of L-methionine in the medium. Putrescine (Type II) stimulated the consumption of S-adenosyl-L-methionine, but did not influence the L-methionine uptake. Hence, the effect of putrescine would be explained by the action to diminish the intracellular level of S-adenosyl-L-methionine. L-Threonine (Type III) neither inhibited the L-methionine uptake nor affected the content of S-adenoxyl-L-methionine due to the addition of L-methionine. (3) The specific activity of homoserine kinase (EC 2.7.1.39) was greatly lowered by the addition of L-methionine under conditions in which Chromatium D unusually accumulates S-adenoxyl-L-methionine. Homoserine dehydrogenase (EC 1.1.1.3) activity was inhbitied by S-adenosyl-L-methionine (50% inhibition index, 3.5 mM). These facts strongly suggest that the growth inhibition by L-methionine is associated with the L-threonine deficiency caused by the unusual accumulation of S-adenosyl-L-methionine.
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Burr B, Walker J, Truffa-Bachi P, Cohen GN. Homoserine kinase from Escherichia coli K12. EUROPEAN JOURNAL OF BIOCHEMISTRY 1976; 62:519-26. [PMID: 177283 DOI: 10.1111/j.1432-1033.1976.tb10186.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Homoserine kinase was purified to apparent homogeneity from a derepressed strain of Escherichia coli K12, using standard fractionation techniques. It is a dimer (Mr = 60000) composed of apparently identical polypeptide chains (Mr = 29000). Its amino acid composition and N-terminal sequence have been determined. L-Threonine is a competitive inhibitor of the substrate L-homoserine; this inhibition is straighforward and shows no sign of co-operativity. Evidence is presented that homoserine and threonine bind to the same site of this non-allosteric enzyme. The binding of homoserine and threonine can also be studied by difference spectroscopy; the latter studies reveal an unexpected effect of magnesium ions, which might be the basis for the unusual high Mg2+ requirement for optimal enzyme reaction.
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Saint-Girons I, Margarita D. Operator-constitutive mutants in the threonine operon of Escherichia coli K-12. J Bacteriol 1975; 124:1137-41. [PMID: 172487 PMCID: PMC236018 DOI: 10.1128/jb.124.3.1137-1141.1975] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Three Escherichia coli K-12 mutant strains resistant to DL-alpha-amino-beta-hydroxyvaleric acid were isolated in which the expression of the thr operon is constitutive. The localization and dominance properties of the mutations involved, called thrO, are those of operator mutations. The gene sequence is OABC as suggested by earlier studies.
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Théze J, Kleidman L, St Girons I. Homoserine kinase from Escherichia coli K-12: properties, inhibition by L-threonine, and regulation of biosynthesis. J Bacteriol 1974; 118:577-81. [PMID: 4364023 PMCID: PMC246790 DOI: 10.1128/jb.118.2.577-581.1974] [Citation(s) in RCA: 41] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
We have partially purified homoserine kinase from a genetically derepressed strain of Escherichia coli K-12. The optimum pH of the enzyme-substrate reaction was 7.8 and the K(m) values for l-homoserine and adenosine 5'-triphosphate were both 3 x 10(-4) M. K(+) (or NH(4) (+)) as well as Mg(2+) were required for its activity. The sedimentation coefficient determined by ultracentrifugation in a sucrose density gradient was 5.0 +/- 0.25S. l-Homoserine was an excellent protector against heat inactivation of homoserine kinase. l-Threonine was a competitive inhibitor of homoserine kinase, suggesting that end-product inhibition of this enzyme plays a role in vivo in the overall regulation of threonine biosynthesis. The specific activity of aspartokinase I-homoserine dehydrogenase I and of homoserine kinase showed a strong positive correlation in extracts from strains under widely varying conditions of genetic or physiological derepression; it was concluded that these two enzymes are coordinately regulated in E. coli K-12.
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Thèze J, Margarita D, Cohen GN, Borne F, Patte JC. Mapping of the structural genes of the three aspartokinases and of the two homoserine dehydrogenases of Escherichia coli K-12. J Bacteriol 1974; 117:133-43. [PMID: 4148765 PMCID: PMC246534 DOI: 10.1128/jb.117.1.133-143.1974] [Citation(s) in RCA: 83] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Mutants requiring threonine plus methionine (or homoserine), or threonine plus methionine plus diaminopimelate (or homoserine plus diaminopimelate) have been isolated from strains possessing only one of the three isofunctional aspartokinases. They have been classified in several groups according to their enzymatic defects. Their mapping is described. Several regions of the chromosome are concerned: thrA (aspartokinase I-homoserine dehydrogenase I) is mapped in the same region as thrB and thrC (0 min). lysC (aspartokinase III) is mapped at 80 min, far from the other genes coding for diaminopimelate synthesis. metLM (aspartokinase II-homoserine dehydrogenase II) lies at 78 min closely linked to metB, metJ, and metF.
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Yen H, Gest H. Regulation of biosynthesis of aspartate family amino acids in the photosynthetic bacterium Rhodopseudomonas palustris. Arch Microbiol 1974; 101:187-210. [PMID: 4374151 DOI: 10.1007/bf00455938] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Abstract
Previous workers divided threonine-requiring (Thr(-)) strains of Salmonella into three phenotypes with mutations in four complementation groups. The mutations were deemed to define four genes in the order thrD-C-A-B at minute zero on the Salmonella linkage map. In the present study 12 of these mutants were reexamined together with eight new Thr(-) strains. The three phenotypes were: homoserine-requiring (Hom(-)); Thr(-), feeders of Hom(-) strains; Thr(-), nonfeeders. Exact correlation between these phenotypic groups and three complementation groups was confirmed by abortive transduction. No evidence was found for intergenic complementation between mutations in Hom(-) strains. It is proposed that thr mutations define three genes rather than four and that these be renamed thrA (Hom(-)), thrB (Thr(-) feeders), and thrC (Thr(-) nonfeeders) to correspond with the sequence of reactions in threonine biosynthesis. Double mutant trpRthr strains were used in reciprocal three-point transduction tests to establish the order of thr mutation sites. Although revisions were made in the classification or location of several mutations, there was an overall correlation of complementation group, phenotype, and map position. The present data provide a basis for further correlation of threonine genes and biosynthetic enzymes, and analysis of cross regulation in aspartate amino acid biosynthesis in Salmonella.
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Schildkraut I, Greer S. Threonine synthetase-catalyzed conversion of phosphohomoserine to alpha-ketobutyrate in Bacillus subtilis. J Bacteriol 1973; 115:777-85. [PMID: 4199513 PMCID: PMC246321 DOI: 10.1128/jb.115.3.777-785.1973] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
An enzyme activity of Bacillus subtilis has been found that catalyzes the dephosphorylation and deamination of phosphohomoserine to alpha-ketobutyrate, resulting in a bypass of threonine in isoleucine biosynthesis. In crude extracts of a strain deficient in the biosynthetic isoleucine-inhibitable threonine dehydratase, phosphohomoserine was converted to alpha-ketobutyrate. Phosphohomoserine conversion to alpha-ketobutyrate was shown not to involve a threonine intermediate. Single mutational events affecting threonine synthetase also affected the phosphohomoserine-deaminating activity, suggesting that the deamination of phosphohomoserine was catalyzed by the threonine synthetase enzyme. It was demonstrated in vivo, in a strain deficient in the biosynthetic threonine dehydratase, that isoleucine was synthesized from homoserine without intermediate formation of threonine.
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Dempsey WB, Sims KR. Isoleucine and threonine can prolong protein and ribonucleic acid synthesis in pyridoxine-starved mutants of Escherichia coli B. J Bacteriol 1972; 112:726-35. [PMID: 4563972 PMCID: PMC251480 DOI: 10.1128/jb.112.2.726-735.1972] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Pyridoxineless mutants of Escherichia coli B stopped incorporation of nucleosides into trichloroacetic acid-insoluble material about 40 to 60 min after pyridoxine starvation was initiated, whereas incorporation of amino acids (measured the same way) slowed but did not stop for several hours. Both these incorporations and cell density were increased most effectively by the presence of either threonine or isoleucine. Arginine, glutamate, histidine, methionine, tryptophan, and tyrosine also caused significant but less dramatic increases. Inducibility of beta-galactosidase continued beyond the point where nucleic acids appeared to stop their synthesis, suggesting that messenger ribonucleic acid synthesis continued beyond ribosomal ribonucleic acid synthesis. This inducibility was also increased by isoleucine and threonine. The overall results suggest that the threonine-isoleucine biosynthetic pathway is the most sensitive to starvation for pyridoxine.
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Vapnek D, Greer S. Minor threonine dehydratase encoded within the threonine synthetic region of Bacillus subtilis. J Bacteriol 1971; 106:983-93. [PMID: 4997544 PMCID: PMC248743 DOI: 10.1128/jb.106.3.983-993.1971] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Challenging auxotrophs on metabolites that are precursors of a biosynthetic step involving a mutated enzyme has revealed a new class of suppressor mutations which act by derepressing a minor enzyme activity not normally detected in the wild-type strain. These indirect, partial suppressor mutations which allow isoleucine auxotrophs to grow on homoserine or threonine have been analyzed to determine their effect on enzymes involved in the biosynthesis of these amino acids. It has been found that one class of these suppressor mutations (sprA) leads to the derepression of homoserine kinase, homoserine dehydrogenase, and a minor threonine dehydratase that is not sufficiently active to be detected in the wild-type strain. The gene encoding this second threonine dehydratase activity has been found to be located between the structural genes for homoserine kinase and homoserine dehydrogenase. The results of these experiments indicate that plating of auxotrophs on precursors of a biosynthetic step involving mutated enzymes could prove to be a valuable method for the detection of regulatory mutants as well as a possible tool in studying the evolution of biochemical pathways.
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Robichon-Szulmajster H. [Diversity of the types of regulation involved in the biosynthesis of threonine and methionine in Saccharomyces cerevisiae]. Biochimie 1971; 53:131-4. [PMID: 5559025 DOI: 10.1016/s0300-9084(71)80043-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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The Regulation of Branched and Converging Pathways. ACTA ACUST UNITED AC 1971. [DOI: 10.1016/b978-0-12-152803-4.50007-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Savageau MA, Steward JP. Repression of the threonine synthetase system in Escherichia coli. Arch Biochem Biophys 1970; 137:181-4. [PMID: 4907804 DOI: 10.1016/0003-9861(70)90425-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Datta P. Regulation of homoserine biosynthesis by L-cysteine, a terminal metabolite of a linked pathway. Proc Natl Acad Sci U S A 1967; 58:635-41. [PMID: 4860755 PMCID: PMC335682 DOI: 10.1073/pnas.58.2.635] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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Patte JC, Le Bras G, Cohen GN. Regulation by methionine of the synthesis of a third aspartokinase and of a second homoserine dehydrogenase in Escherichia coli K 12. BIOCHIMICA ET BIOPHYSICA ACTA 1967; 136:245-7. [PMID: 4860558 DOI: 10.1016/0304-4165(67)90069-4] [Citation(s) in RCA: 113] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Municio AM, Vega A. The behaviour of aspartate semialdehyde as a precursor of the intra- and extracellular amino acids in Escherichia coli 26-26. BIOCHIMICA ET BIOPHYSICA ACTA 1966; 127:317-24. [PMID: 5337448 DOI: 10.1016/0304-4165(66)90386-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Abstract
Hodson, Phillip H. (University of Texas, Austin), and J. W. Foster. Dipicolinic acid synthesis in Penicillium citreo-viride. J. Bacteriol. 91:562-569. 1966.-Dipicolinic acid (DPA) accumulation in culture filtrates of the mold Penicillium citreo-viride was studied in surface and submerged cultures. Good DPA yields were obtained in suspensions of washed, submerged mycelium in the presence of a carbon and a nitrogen source but in the absence of other minerals essential for growth. Fumaric acid was the only other acid formed in significant amounts. Glucose and glycerol were superior to various salts of organic acids as carbon sources, and certain amino acids were excellent nitrogen sources. l-Leucine, l-norvaline, l-tyrosine, and l-histidine were superior to urea, NH(4)Cl, or NaNO(3) as nitrogen precursors for DPA production. d-Norvaline was useless for DPA production. Glycerol-2-C(14) and -1-C(14), C(14)O(2), and l-leucine-C(14), l-tyrosine-C(14), and l-histidine-C(14) were tested as precursors in conjunction with suitable carbon and nitrogen sources. The DPA was decarboxylated chemically, and the distribution of C(14) was determined in the pyridine-C and in the carboxyl-C. The data are consistent with Martin and Foster's suggestion for bacteria that the DPA molecule is formed by a condensation of C(3) plus C(4) precursors, the resulting 2-keto, 6-aminopimelic acid derivate undergoing ring closure to form a heterocyclic precursor of DPA. The C(14)O(2) experiments indicate that oxaloacetate is formed by beta-carboxylation of pyruvate, this in turn probably becoming aspartic acid beta-semialdehyde, the C(4) compound which condenses with a second pyruvate. The enhancement of DPA formation by l-norvaline, l-leucine, and l-histidine is not ascribable to their functioning either as a source of nitrogen or carbon. l-Tyrosine, in a glycerol medium, contributed nearly 40% of the DPA carbon. The mechanism of biosynthesis of C(7) straight-chain and cyclic compounds is discussed.
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FREUNDLICH M. Multivalent repression in the biosynthesis of threonine in Salmonella typhimurium and Escherichia coli. Biochem Biophys Res Commun 1963; 10:277-82. [PMID: 13959617 DOI: 10.1016/0006-291x(63)90430-3] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/24/2023]
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