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Isogai S, Nishimura A, Inoue A, Sonohara S, Tsugukuni T, Okada T, Takagi H. Functional analysis of feedback inhibition-insensitive aspartate kinase identified in a threonine-accumulating mutant of Saccharomyces cerevisiae. Appl Environ Microbiol 2024; 90:e0015524. [PMID: 38456673 PMCID: PMC11022571 DOI: 10.1128/aem.00155-24] [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: 01/29/2024] [Accepted: 02/15/2024] [Indexed: 03/09/2024] Open
Abstract
Humans and mammals need to ingest essential amino acids (EAAs) for protein synthesis. In addition to their importance as nutrients, EAAs are involved in brain homeostasis. However, elderly people are unable to efficiently consume EAAs from their daily diet due to reduced appetite and variations in the contents of EAAs in foods. On the other hand, strains of the yeast Saccharomyces cerevisiae that accumulate EAAs would enable elderly people to intakegest adequate amounts of EAAs and thus might slow down the neurodegenerative process, contributing to the extension of their healthy lifespan. In this study, we isolated a mutant (strain HNV-5) that accumulates threonine, an EAA, derived from a diploid laboratory yeast by conventional mutagenesis. Strain HNV-5 carries a novel mutation in the HOM3 gene encoding the Ala462Thr variant of aspartate kinase (AK). Enzymatic analysis revealed that the Ala462Thr substitution significantly decreased the sensitivity of AK activity to threonine feedback inhibition even in the presence of 50 mM threonine. Interestingly, Ala462Thr substitution did not affect the catalytic ability of Hom3, in contrast to previously reported amino acid substitutions that resulted in reduced sensitivity to threonine feedback inhibition. Furthermore, yeast cells expressing the Ala462Thr variant showed an approximately threefold increase in intracellular threonine content compared to that of the wild-type Hom3. These findings will be useful for the development of threonine-accumulating yeast strains that may improve the quality of life in elderly people.IMPORTANCEFor humans and mammals, essential amino acids (EAAs) play an important role in maintaining brain function. Therefore, increasing the intake of EAAs by using strains of the yeast Saccharomyces cerevisiae that accumulate EAAs may inhibit neurodegeneration in elderly people and thus contribute to extending healthy lifespan and improving their quality of life. Threonine, an EAA, is synthesized from aspartate. Aspartate kinase (AK) catalyzes the first step in threonine biosynthesis and is subject to allosteric regulation by threonine. Here, we isolated a threonine-accumulating mutant of S. cerevisiae by conventional mutagenesis and identified a mutant gene encoding a novel variant of AK. In contrast to previously isolated variants, the Hom3 variant exhibited AK activity that was insensitive to feedback inhibition by threonine but retained its catalytic ability. This resulted in increased production of threonine in yeast. These findings open up the possibility for the rational design of AK to increase threonine productivity in yeast.
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Affiliation(s)
- Shota Isogai
- Institute for Research Initiative, Nara Institute of Science and Technology, Takayama, Nara, Japan
| | - Akira Nishimura
- Institute for Research Initiative, Nara Institute of Science and Technology, Takayama, Nara, Japan
| | - Akiko Inoue
- Institute for Research Initiative, Nara Institute of Science and Technology, Takayama, Nara, Japan
| | - Shino Sonohara
- Plant Bio Business Unit, Musashi Seimitsu Industry Co., Ltd., Toyohashi, Aichi, Japan
| | - Takashi Tsugukuni
- Plant Bio Business Unit, Musashi Seimitsu Industry Co., Ltd., Toyohashi, Aichi, Japan
| | - Tomoyuki Okada
- Plant Bio Business Unit, Musashi Seimitsu Industry Co., Ltd., Toyohashi, Aichi, Japan
| | - Hiroshi Takagi
- Institute for Research Initiative, Nara Institute of Science and Technology, Takayama, Nara, Japan
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Ianshina T, Sidorin A, Petrova K, Shubert M, Makeeva A, Sambuk E, Govdi A, Rumyantsev A, Padkina M. Effect of Methionine on Gene Expression in Komagataella phaffii Cells. Microorganisms 2023; 11:microorganisms11040877. [PMID: 37110303 PMCID: PMC10143545 DOI: 10.3390/microorganisms11040877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 03/27/2023] [Accepted: 03/27/2023] [Indexed: 04/01/2023] Open
Abstract
Komagataella phaffii yeast plays a prominent role in modern biotechnology as a recombinant protein producer. For efficient use of this yeast, it is essential to study the effects of different media components on its growth and gene expression. We investigated the effect of methionine on gene expression in K. phaffii cells using RNA-seq analysis. Several gene groups exhibited altered expression when K. phaffii cells were cultured in a medium with methanol and methionine, compared to a medium without this amino acid. Methionine primarily affects the expression of genes involved in its biosynthesis, fatty acid metabolism, and methanol utilization. The AOX1 gene promoter, which is widely used for heterologous expression in K. phaffii, is downregulated in methionine-containing media. Despite great progress in the development of K. phaffii strain engineering techniques, a sensitive adjustment of cultivation conditions is required to achieve a high yield of the target product. The revealed effect of methionine on K. phaffii gene expression is important for optimizing media recipes and cultivation strategies aimed at maximizing the efficiency of recombinant product synthesis.
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Affiliation(s)
- Tatiana Ianshina
- Laboratory of Biochemical Genetics, Department of Genetics and Biotechnology, Saint Petersburg State University (SPBU), Saint Petersburg 199034, Russia
| | - Anton Sidorin
- Laboratory of Biochemical Genetics, Department of Genetics and Biotechnology, Saint Petersburg State University (SPBU), Saint Petersburg 199034, Russia
| | - Kristina Petrova
- Laboratory of Biochemical Genetics, Department of Genetics and Biotechnology, Saint Petersburg State University (SPBU), Saint Petersburg 199034, Russia
| | - Maria Shubert
- Laboratory of Biochemical Genetics, Department of Genetics and Biotechnology, Saint Petersburg State University (SPBU), Saint Petersburg 199034, Russia
| | - Anastasiya Makeeva
- Laboratory of Biochemical Genetics, Department of Genetics and Biotechnology, Saint Petersburg State University (SPBU), Saint Petersburg 199034, Russia
| | - Elena Sambuk
- Laboratory of Biochemical Genetics, Department of Genetics and Biotechnology, Saint Petersburg State University (SPBU), Saint Petersburg 199034, Russia
| | - Anastasiya Govdi
- Institute of Chemistry, Saint Petersburg State University (SPBU), Petergof, Saint Petersburg 198504, Russia
| | - Andrey Rumyantsev
- Laboratory of Biochemical Genetics, Department of Genetics and Biotechnology, Saint Petersburg State University (SPBU), Saint Petersburg 199034, Russia
- Correspondence: (A.R.); (M.P.)
| | - Marina Padkina
- Laboratory of Biochemical Genetics, Department of Genetics and Biotechnology, Saint Petersburg State University (SPBU), Saint Petersburg 199034, Russia
- Correspondence: (A.R.); (M.P.)
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Liang X, Deng H, Bai Y, Fan TP, Zheng X, Cai Y. Characterization of a novel type homoserine dehydrogenase with high oxidation activity from Arthrobacter nicotinovorans. Process Biochem 2022. [DOI: 10.1016/j.procbio.2022.01.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Metabolic engineering of a synergistic pathway for n-butanol production in Saccharomyces cerevisiae. Sci Rep 2016; 6:25675. [PMID: 27161023 PMCID: PMC4861978 DOI: 10.1038/srep25675] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 04/21/2016] [Indexed: 11/23/2022] Open
Abstract
n-Butanol has several favourable properties as an advanced fuel or a platform chemical. Bio-based production of n-butanol is becoming increasingly important for sustainable chemical industry. Synthesis of n-butanol can be achieved via more than one metabolic pathway. Here we report the metabolic engineering of Saccharomyces cerevisiae to produce n-butanol through a synergistic pathway: the endogenous threonine pathway and the introduced citramalate pathway. Firstly, we characterized and optimized the endogenous threonine pathway; then, a citramalate synthase (CimA) mediated pathway was introduced to construct the synergistic pathway; next, the synergistic pathway was optimized by additional overexpression of relevant genes identified previously; meanwhile, the n-butanol production was also improved by overexpression of keto-acid decarboxylases (KDC) and alcohol dehydrogenase (ADH). After combining these strategies with co-expression of LEU1 (two copies), LEU4, LEU2 (two copies), LEU5, CimA, NFS1, ADH7 and ARO10*, we achieved an n-butanol production of 835 mg/L in the final engineered strain, which is almost 7-fold increase compared to the initial strain. Furthermore, the production showed a 3-fold of the highest titer ever reported in yeast. Therefore, the engineered yeast strain represents a promising alternative platform for n-butanol production.
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Kriel J, Haesendonckx S, Rubio-Texeira M, Van Zeebroeck G, Thevelein JM. From transporter to transceptor: signaling from transporters provokes re-evaluation of complex trafficking and regulatory controls: endocytic internalization and intracellular trafficking of nutrient transceptors may, at least in part, be governed by their signaling function. Bioessays 2011; 33:870-9. [PMID: 21913212 PMCID: PMC3258547 DOI: 10.1002/bies.201100100] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
When cells are starved of their substrate, many nutrient transporters are induced. These undergo rapid endocytosis and redirection of their intracellular trafficking when their substrate becomes available again. The discovery that some of these transporters also act as receptors, or transceptors, suggests that at least part of the sophisticated controls governing the trafficking of these proteins has to do with their signaling function rather than with control of transport. In yeast, the general amino acid permease Gap1 mediates signaling to the protein kinase A pathway. Its endocytic internalization and intracellular trafficking are subject to amino acid control. Other nutrient transceptors controlling this signal transduction pathway appear to be subject to similar trafficking regulation. Transporters with complex regulatory control have also been suggested to function as transceptors in other organisms. Hence, precise regulation of intracellular trafficking in nutrient transporters may be related to the need for tight control of nutrient-induced signaling.
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Affiliation(s)
- Johan Kriel
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, K. U. Leuven, Leuven, Belgium
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Homoserine toxicity in Saccharomyces cerevisiae and Candida albicans homoserine kinase (thr1Delta) mutants. EUKARYOTIC CELL 2010; 9:717-28. [PMID: 20305002 DOI: 10.1128/ec.00044-10] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In addition to threonine auxotrophy, mutation of the Saccharomyces cerevisiae threonine biosynthetic genes THR1 (encoding homoserine kinase) and THR4 (encoding threonine synthase) results in a plethora of other phenotypes. We investigated the basis for these other phenotypes and found that they are dependent on the toxic biosynthetic intermediate homoserine. Moreover, homoserine is also toxic for Candida albicans thr1Delta mutants. Since increasing levels of threonine, but not other amino acids, overcome the homoserine toxicity of thr1Delta mutants, homoserine may act as a toxic threonine analog. Homoserine-mediated lethality of thr1Delta mutants is blocked by cycloheximide, consistent with a role for protein synthesis in this lethality. We identified various proteasome and ubiquitin pathway components that either when mutated or present in high copy numbers suppressed the thr1Delta mutant homoserine toxicity. Since the doa4Delta and proteasome mutants identified have reduced ubiquitin- and/or proteasome-mediated proteolysis, the degradation of a particular protein or subset of proteins likely contributes to homoserine toxicity.
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Bayer TS, Widmaier DM, Temme K, Mirsky EA, Santi DV, Voigt CA. Synthesis of methyl halides from biomass using engineered microbes. J Am Chem Soc 2009; 131:6508-15. [PMID: 19378995 DOI: 10.1021/ja809461u] [Citation(s) in RCA: 163] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Methyl halides are used as agricultural fumigants and are precursor molecules that can be catalytically converted to chemicals and fuels. Plants and microorganisms naturally produce methyl halides, but these organisms produce very low yields or are not amenable to industrial production. A single methyl halide transferase (MHT) enzyme transfers the methyl group from the ubiquitous metabolite S-adenoyl methionine (SAM) to a halide ion. Using a synthetic metagenomic approach, we chemically synthesized all 89 putative MHT genes from plants, fungi, bacteria, and unidentified organisms present in the NCBI sequence database. The set was screened in Escherichia coli to identify the rates of CH(3)Cl, CH(3)Br, and CH(3)I production, with 56% of the library active on chloride, 85% on bromide, and 69% on iodide. Expression of the highest activity MHT and subsequent engineering in Saccharomyces cerevisiae results in productivity of 190 mg/L-h from glucose and sucrose. Using a symbiotic co-culture of the engineered yeast and the cellulolytic bacterium Actinotalea fermentans, we are able to achieve methyl halide production from unprocessed switchgrass (Panicum virgatum), corn stover, sugar cane bagasse, and poplar (Populus sp.). These results demonstrate the potential of producing methyl halides from non-food agricultural resources.
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Affiliation(s)
- Travis S Bayer
- Department of Pharmaceutical Chemistry, University of California, San Francisco, MC 2540, Room 408C, 1700 4th Street, San Francisco, California 94158-2330, USA
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Development of bottom-fermenting saccharomyces strains that produce high SO2 levels, using integrated metabolome and transcriptome analysis. Appl Environ Microbiol 2008; 74:2787-96. [PMID: 18310411 DOI: 10.1128/aem.01781-07] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sulfite plays an important role in beer flavor stability. Although breeding of bottom-fermenting Saccharomyces strains that produce high levels of SO(2) is desirable, it is complicated by the fact that undesirable H(2)S is produced as an intermediate in the same pathway. Here, we report the development of a high-level SO(2)-producing bottom-fermenting yeast strain by integrated metabolome and transcriptome analysis. This analysis revealed that O-acetylhomoserine (OAH) is the rate-limiting factor for the production of SO(2) and H(2)S. Appropriate genetic modifications were then introduced into a prototype strain to increase metabolic fluxes from aspartate to OAH and from sulfate to SO(2), resulting in high SO(2) and low H(2)S production. Spontaneous mutants of an industrial strain that were resistant to both methionine and threonine analogs were then analyzed for similar metabolic fluxes. One promising mutant produced much higher levels of SO(2) than the parent but produced parental levels of H(2)S.
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Velasco I, Tenreiro S, Calderon IL, André B. Saccharomyces cerevisiae Aqr1 is an internal-membrane transporter involved in excretion of amino acids. EUKARYOTIC CELL 2005; 3:1492-503. [PMID: 15590823 PMCID: PMC539038 DOI: 10.1128/ec.3.6.1492-1503.2004] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Excretion of amino acids by yeast cells was reported long ago but has not been characterized in molecular terms. It is typically favored by overproduction of the amino acid and/or impairment of its uptake. Here we describe the construction of a yeast strain excreting threonine and homoserine. Using this excretor strain, we then applied a reverse-genetics approach and found that the transporter encoded by the YNL065w/AQR1 gene, a protein thought to mediate H(+) antiport, is involved in homoserine and threonine excretion. Furthermore, overexpression of AQR1 led to increased excretion of several amino acids (alanine, aspartate, and glutamate) known to be relatively abundant in the cytosol. Transcription of the AQR1 gene is induced severalfold by a number of amino acids and appears to be under the negative control of Gcn4. An Aqr1-green fluorescent protein fusion protein is located in multiple internal membrane structures and appears to cycle continuously between these compartments and the plasma membrane. The Aqr1 sequence is significantly similar to the vesicular amine transporters of secretory vesicles of neuronal cells. We propose that Aqr1 catalyzes transport of excess amino acids into vesicles, which then release them in the extracellular space by exocytosis.
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Affiliation(s)
- Isabel Velasco
- Physiologie Moléculaire de la Cellule, Université Libre de Bruxelles, Institut de Biologie et de Médecine Moléculaires, 12 rue des Pr. Jeener et Brachet, 6041 Gosselies, Belgium
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Velasco I, Arévalo-Rodríguez M, Marina P, Calderón IL. A new mutation in the yeast aspartate kinase induces threonine accumulation in a temperature-regulated way. Yeast 2005; 22:99-110. [PMID: 15645479 DOI: 10.1002/yea.1197] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In Saccharomyces cerevisiae, aspartate kinase (the HOM3 product) regulates the metabolic flux through the threonine biosynthetic pathway through feedback inhibition by the end product. In order to obtain a strain able to produce threonine in a controlled way, we have isolated a mutant allele (HOM3-ts31d) that gives rise to a deregulated aspartate kinase. This allele has been isolated as an extragenic suppressor of ilv1, which confers an Ilv+ phenotype at 37 degrees C but not at 22 degrees C. We have stated that at high temperature the mutant aspartate kinase is slightly more deregulated and shows a higher specific activity, inducing threonine accumulation. The HOM3-ts31d allele carries a mutation that leads to a Ser399 --> Phe substitution in the postulated regulatory region of the enzyme. We have detected other changes in the nucleotide sequence but they are also present in the parental strain, reflecting the genetic differences between different wild-type strains. A sequence comparison among all the reported mutant aspartate kinases suggests that not all residues involved in regulation of the activity are clustered in the so-called regulatory domain, as is the case of that mutated in AK-R7, another deregulated aspartate kinase obtained with the same strategy of ilv1 suppression.
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Affiliation(s)
- I Velasco
- Departamento de Genética, Universidad de Sevilla, Sevilla, Spain
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Galili G. New insights into the regulation and functional significance of lysine metabolism in plants. ANNUAL REVIEW OF PLANT BIOLOGY 2002; 53:27-43. [PMID: 12221976 DOI: 10.1146/annurev.arplant.53.091401.110929] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Lysine is one of the most limiting essential amino acids in vegetative foods consumed by humans and livestock. In addition to serving as a building block of proteins, lysine is also a precursor for glutamate, an important signaling amino acid that regulates plant growth and responses to the environment. Recent genetic, molecular, and biochemical evidence suggests that lysine synthesis and catabolism are regulated by novel concerted mechanisms. These include intracellular compartmentalization of enzymes and metabolites, complex transcriptional and posttranscriptional controls of genes encoding enzymes in lysine metabolism during plant growth and development, as well as interactions between different metabolic fluxes. The recent advances in our understanding of the regulation of lysine metabolism in plants may also prove valuable for future production of high-lysine crops.
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Affiliation(s)
- Gad Galili
- Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
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Chassagnole C, Fell DA, Raïs B, Kudla B, Mazat JP. Control of the threonine-synthesis pathway in Escherichia coli: a theoretical and experimental approach. Biochem J 2001; 356:433-44. [PMID: 11368770 PMCID: PMC1221854 DOI: 10.1042/0264-6021:3560433] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A computer simulation of the threonine-synthesis pathway in Escherichia coli Tir-8 has been developed based on our previous measurements of the kinetics of the pathway enzymes under near-physiological conditions. The model successfully simulates the main features of the time courses of threonine synthesis previously observed in a cell-free extract without alteration of the experimentally determined parameters, although improved quantitative fits can be obtained with small parameter adjustments. At the concentrations of enzymes, precursors and products present in cells, the model predicts a threonine-synthesis flux close to that required to support cell growth. Furthermore, the first two enzymes operate close to equilibrium, providing an example of a near-equilibrium feedback-inhibited enzyme. The predicted flux control coefficients of the pathway enzymes under physiological conditions show that the control of flux is shared between the first three enzymes: aspartate kinase, aspartate semialdehyde dehydrogenase and homoserine dehydrogenase, with no single activity dominating the control. The response of the model to the external metabolites shows that the sharing of control between the three enzymes holds across a wide range of conditions, but that the pathway flux is sensitive to the aspartate concentration. When the model was embedded in a larger model to simulate the variable demands for threonine at different growth rates, it showed the accumulation of free threonine that is typical of the Tir-8 strain at low growth rates. At low growth rates, the control of threonine flux remains largely with the pathway enzymes. As an example of the predictive power of the model, we studied the consequences of over-expressing different enzymes in the pathway.
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Affiliation(s)
- C Chassagnole
- INSERM EMI 9929, University Victor Segalen Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux, France
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Enrichment of threonine content in Saccharomyces cerevisiae by pathway engineering. Enzyme Microb Technol 2000; 26:763-770. [PMID: 10862883 DOI: 10.1016/s0141-0229(00)00169-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In a previous work, we have investigated the effect of amplifying individually the genes of the threonine biosynthetic pathway on threonine accumulation by yeast. Here, we present the results of the simultaneous amplification of these genes in strains with different genetic backgrounds. These strains carry a mutant HOM3-R2 allele (coding for a feedback-insensitive aspartate kinase), and/or a mutant cha1 allele that makes it defective in threonine degradation by the catabolic L-serine (L-threonine) deaminase. The results show that the amplification of the clustered genes affects threonine and homoserine accumulation only when it includes the HOM3 gene, or when combined with a HOM3-R2 mutation. Similarly, the cha1 mutation is only effective when a certain amount of threonine is reached. Threonine overproduction affects other cellular functions such as the accumulation of other amino acids, the cell growth and metabolite excretion, probably reflecting a redirection of the carbon flux in the central metabolism.
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