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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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de Lima LA, Ventorim RZ, Bianchini IA, de Queiroz MV, Fietto LG, da Silveira WB. Obtainment, selection and characterization of a mutant strain of Kluyveromyces marxianus that displays improved production of 2-phenylethanol and enhanced DAHP synthase activity. J Appl Microbiol 2020; 130:878-890. [PMID: 32706912 DOI: 10.1111/jam.14793] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 06/11/2020] [Accepted: 07/20/2020] [Indexed: 12/26/2022]
Abstract
AIMS Yeasts produce 2-phenylethanol (2-PE) from sugars via de novo synthesis; however, its synthesis is limited due to feedback inhibition on the isofunctional 3-deoxy-d-arabino-heptulosonate-7-phosphate (DAHP) synthases (Aro3p and Aro4p). This work aimed to select Kluyveromyces marxianus mutant strains with improved capacity to produce 2-PE from sugars. METHODS AND RESULTS Kluyveromyces marxianus CCT 7735 mutant strains were selected from UV irradiation coupled with screening of p-fluoro-dl-phenylalanine (PFP) tolerant strains on culture medium without l-Phe addition. Most of them produced 2-PE titres higher than the parental strain and the Km_PFP41 mutant strain stood out for displaying the highest 2-PE specific production rate. Moreover it showed higher activity of DAHP synthase than the parental strain. We sequenced both ARO3 and ARO4 genes of Km_PFP41 mutant and identified mutations in ARO4 which caused changes in both size and conformation of the Aro4p. These changes seem to be associated with the enhanced activity of DAHP synthase and improved production of 2-PE exhibited by that mutant strain. CONCLUSIONS The Km_PFP41 mutant strain presented improved 2-PE production via de novo synthesis and enhanced DAHP synthase activity. SIGNIFICANCE AND IMPACT OF THE STUDY The mutant strain obtained in this work may be exploited as a yeast cell factory for high-level synthesis of 2-PE.
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Affiliation(s)
- L A de Lima
- Department of Microbiology, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - R Z Ventorim
- Department of Microbiology, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - I A Bianchini
- Department of Microbiology, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - M V de Queiroz
- Department of Microbiology, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - L G Fietto
- Department of Biochemistry and Molecular Biology, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - W B da Silveira
- Department of Microbiology, Universidade Federal de Viçosa, Viçosa, MG, Brazil
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Dueñas-Sánchez R, Pérez AG, Codón AC, Benítez T, Rincón AM. Overproduction of 2-phenylethanol by industrial yeasts to improve organoleptic properties of bakers' products. Int J Food Microbiol 2014; 180:7-12. [DOI: 10.1016/j.ijfoodmicro.2014.03.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 03/10/2014] [Accepted: 03/27/2014] [Indexed: 11/29/2022]
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Saengkerdsub S, Muthaiyan A, Lingbeck JM, O'Bryan CA, Crandall PG, Ricke SC. Identification and methionine analog tolerance of environmental bacterial isolates selected on methionine analog containing medium. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART. B, PESTICIDES, FOOD CONTAMINANTS, AND AGRICULTURAL WASTES 2014; 49:290-298. [PMID: 24502216 DOI: 10.1080/03601234.2014.868668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Methionine is the first limiting amino acid in poultry feed. Currently, methionine supplement is synthesized from an expensive chemical process requiring hazardous chemicals. Therefore, the objectives of this study were isolation of methionine producing bacteria from environmental samples and quantification of methionine production in these isolated bacteria. MCGC medium was selected as the isolation medium for methionine-producing bacteria by using Corynebacterium glutamicum ATCC13032 and Escherichia coli ATCC23798 as the positive and negative controls, respectively. Thirty-nine bacterial strains were obtained from environmental samples. Only strains A121, A122, A151 and A181 were able to tolerate up to 0.1% (w/v) of ethionine or norleucine. These isolated strains were identified by sequencing small subunit rRNA genes. The results revealed that bacterial strains A121, A122, A151and A181 were Klebsiella species, Acinetobacter baumannii, A. baumannii and Pseudomonas aeruginosa, respectively. When methionine production in strains A121 and A181 was quantitated, strains A121 and A181 generated methionine up to 31.1 and 124.6 μg/ml, respectively.
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Affiliation(s)
- Suwat Saengkerdsub
- a Center for Food Safety, and Department of Food Science , University of Arkansas , Fayetteville , Arkansas , USA
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5
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Abstract
In this work, we have studied the effect of amplifying different alleles involved in the threonine biosynthesis on the amino acid production by Saccharomyces cerevisiae. The genes used were wild-type HOM3, HOM2, HOM6, THR1, and THR4, and two mutant alleles of HOM3 (namely HOM3-R2 and HOM3-R6), that code for feedback-insensitive aspartate kinases. The results show that only the amplification of the HOM3 alleles leads to threonine and, in some instances, to homoserine overproduction. In terms of the regulation of the pathway, the data indicate that the main control is exerted by inhibition of the aspartate kinase and that, probably, a second and less important regulation takes place at the level of the homoserine kinase, the THR1 gene product. However, amplification of THR1 in two related Hom3-R2 strains does not increase the amount of threonine but, in one of them, it does induce accumulation of more homoserine. This result probably reflects differences between these strains in some undetermined genetic factor/s related with threonine metabolism. In general, the data indicate that the common laboratory yeast strains are genetically rather heterogeneous and, thus, extrapolation of conclusions must be done carefully. (c) 1996 John Wiley & Sons, Inc.
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Affiliation(s)
- M J Farfán
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Ap. 1095, E-41080 Sevilla, Spain
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Shao S, Zhou T, McGarvey BD. Comparative metabolomic analysis of Saccharomyces cerevisiae during the degradation of patulin using gas chromatography-mass spectrometry. Appl Microbiol Biotechnol 2011; 94:789-97. [PMID: 22159606 DOI: 10.1007/s00253-011-3739-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 11/01/2011] [Accepted: 11/15/2011] [Indexed: 11/29/2022]
Abstract
A comparative metabolomic analysis was conducted on Saccharomyces cerevisiae cells with and without patulin treatment using gas chromatography-mass spectrometry-based approach. A total of 72 metabolites were detected and compared, including 16 amino acids, 29 organic acids and alcohols, 19 sugars and sugar alcohols, 2 nucleotides, and 6 miscellaneous compounds. Principle component analysis showed a clear separation of metabolome between the cells with and without patulin treatment, and most of the identified metabolites contributed to the separation. A close examination of the identified metabolites showed an increased level of most of the free amino acids, an increased level of the intermediates in the tricarboxylic acid cycle, a higher amount of glycerol, a changed fatty acid composition, and a decreased level of cysteine and glutathione in the cells with patulin treatment. This finding indicated a slower protein synthesis rate and induced oxidative stress in the cells with patulin treatment, and provided new insights into the effect of toxic chemicals on the metabolism of organisms.
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Affiliation(s)
- Suqin Shao
- Guelph Food Research Centre, Agriculture & Agri-Food Canada, 93 Stone Road West, Guelph, Ontario, Canada N1G 5C9
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Sands DC, Pilgeram AL. Methods for selecting hypervirulent biocontrol agents of weeds: why and how. PEST MANAGEMENT SCIENCE 2009; 65:581-587. [PMID: 19288472 DOI: 10.1002/ps.1739] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A considerable number of plant pathogens have been studied for their possible use in weed control. Some have proven virulent enough to control weed species and to compete commercially with chemical herbicides. However, most pathogens of weeds are not useful in their wild form because they are not sufficiently host-specific and/or virulent. The authors believe that these barriers can be overcome. The present research has focused on the inhibitory effects of certain amino acids on the growth and development of specific plants. Pathogens that overproduce these selected amino acids can be easily selected from a pool of spontaneous mutants. Such mutants can have increased pathogenicity to their target weed and enhanced field performance as biocontrol agents. Enhancement of biocontrol efficacy in three separate pathogen-host systems, two with Fusarium and one with Pseudomonas, has already been reported. It is proposed to use the same technology to enhance the biocontrol efficacy of the two species of Fusarium that are host-specific pathogens of the broomrape group of parasitic weeds. The stepwise approach outlined can lead to obtaining enhanced biocontrol agents capable of producing inhibitory levels of selected amino acids in situ. It is proposed that these approaches, in combination with other methods of virulence enhancement, will lead to sustainable systems of biological control of parasitic weeds.
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Affiliation(s)
- David C Sands
- Montana State University, 119 Plant Bioscience Building, Bozeman, MT 59717-3150, USA.
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Kim SH, Ha YM, Youm HJ, An GH, Lee BD, Won MS, Song KB. Isolation of a Tryptophan-Overproducing Strain Generated by EMS Mutagenesis of Candida rugosa. Prev Nutr Food Sci 2004. [DOI: 10.3746/jfn.2004.9.2.187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Kim TG, Kim J, Kim DH, Yang MS. Expression of nutritionally well-balanced protein, AmA1, inSaccharomyces cerevisiae. BIOTECHNOL BIOPROC E 2001. [DOI: 10.1007/bf02932546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Rincón AM, Benítez T. Improved organoleptic and nutritive properties of bakery products supplemented with amino acid overproducing Saccharomyces cerevisiae yeasts. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2001; 49:1861-1866. [PMID: 11308337 DOI: 10.1021/jf001130u] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Spontaneous yeast mutants isolated in continuous culture as resistant to toxic amino acid analogues, able to increase up to 40 times their free amino acid pool of Thr, up to 160 times their pool of Met, or up to 20 times their pool of Lys, were characterized with regard to properties of industrial interest. Growth rate, mu (h(-1)), and biomass yield, Y (g/L), of the amino acid overproducing mutants (AA(S)) were in many cases similar to those of the wild type, whereas their free amino acid content was substantially increased in laboratory and industrial media (molasses). Doughs fermented with 3% baker's yeast and 0.5% AA(S) mutants produced bakery products that displayed texture similar to those fermented with 3.5% baker's yeast, but the former had a considerable improvement of their taste and aroma. On the other hand, bread content of the essential amino acids Lys, Met, and Thr provided by yeast was also increased.
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Affiliation(s)
- A M Rincón
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Apartado 1095, E-41080 Sevilla, Spain
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11
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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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12
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Farfán MJ, Aparicio L, Calderón IL. Threonine overproduction in yeast strains carrying the HOM3-R2 mutant allele under the control of different inducible promoters. Appl Environ Microbiol 1999; 65:110-6. [PMID: 9872767 PMCID: PMC90990 DOI: 10.1128/aem.65.1.110-116.1999] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The HOM3 gene of Saccharomyces cerevisiae codes for aspartate kinase, which plays a crucial role in the regulation of the metabolic flux that leads to threonine biosynthesis. With the aim of obtaining yeast strains able to overproduce threonine in a controlled way, we have placed the HOM3-R2 mutant allele, which causes expression of a feedback-insensitive enzyme, under the control of four distinctive regulatable yeast promoters, namely, PGAL1, PCHA1, PCYC1-HSE2, and PGPH1. The amino acid contents of strains bearing the different constructs were analyzed both under repression and induction conditions. Although some differences in overall threonine production were found, a maximum of around 400 nmol/mg (dry weight) was observed. Other factors, such as excretion to the medium and activity of the catabolic threonine/serine deaminase, also affect threonine accumulation. Thus, improvement of threonine productivity by yeast cells would probably require manipulation of these and other factors.
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Affiliation(s)
- M J Farfán
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, E-41080 Seville, Spain
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13
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Casalone E, Fia G, Barberio C, Cavalieri D, Turbanti L, Polsinelli M. Genetic and biochemical characterization of Saccharomyces cerevisiae mutants resistant to trifluoroleucine. Res Microbiol 1997; 148:613-23. [PMID: 9765846 DOI: 10.1016/s0923-2508(97)88085-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Eighteen mutants resistant to 5',5',5'-trifluoroleucine (TFL), a leucine analog, were isolated in Saccharomyces cerevisiae strains YNN281 and YNN282. The mutants were characterized genetically and clustered in two groups, one comprising all the dominant (TFL1) and the other one all the recessive (tfl2) mutations. Genetic and biochemical data suggested that the dominant mutations are located on the LEU4 gene, coding for alpha-isopropylmalate synthase I. These mutations resulted in accumulation of leucine as a consequence of the synthesis of an enzyme insensitive to the feedback inhibition by leucine. Leucine excretion in the TFL1 mutants appeared to be affected by the genetic background of the strain and was greatly influenced by lysine metabolism. The measurement of intra- and extracellular amino acid concentrations in prototrophic strains carrying TFL1 or tfl2 genes showed that both were leucine overproducers. Some of the TFL-resistant mutants were tested in alcoholic fermentation of grape must: analysis of the fermentation secondary metabolites showed that the major effect of the TFL-resistant strains was an increased production of isoamyl alcohol compared to that of the parental strain.
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Affiliation(s)
- E Casalone
- Department of Animal Biology and Genetics, University of Florence, Italy
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14
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TheSAM2 gene product catalyzes the formation of S-adenosyl-ethionine from ethionine inSaccharomyces cerevisiae. Curr Microbiol 1994. [DOI: 10.1007/bf01570198] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Martin-Rendon E, Farfán MJ, Ramos C, Calderon IL. Isolation of a mutant allele that deregulates the threonine biosynthesis in Saccharomyces cerevisiae. Curr Genet 1993; 24:465-71. [PMID: 8299165 DOI: 10.1007/bf00351707] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We have cloned the yeast allele HOM3-R2, that codes for a mutant aspartate kinase which is insensitive to feedback inhibition by threonine, by gap-repair. A strain carrying this allele in a multicopy plasmid, or integrated into the genome, accumulates 14-times and 8-times more threonine than the wild-type, respectively. The sequence of the mutant allele differs from that of the wild-type in a single base pair change, namely a G by an A, at position 1355 in the open reading frame. The fact that the presence of this mutant allele in a cell induces threonine overproduction points to aspartate kinase as the key enzyme in the regulation of threonine biosynthesis in yeast.
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Affiliation(s)
- E Martin-Rendon
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Spain
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Martínez-Force E, Benítez T. Regulation of aspartate-derived amino acid biosynthesis in the yeastSaccharomyces cerevisiae. Curr Microbiol 1993. [DOI: 10.1007/bf01576262] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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