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Wasylenko TM, Ahn WS, Stephanopoulos G. The oxidative pentose phosphate pathway is the primary source of NADPH for lipid overproduction from glucose in Yarrowia lipolytica. Metab Eng 2015; 30:27-39. [PMID: 25747307 DOI: 10.1016/j.ymben.2015.02.007] [Citation(s) in RCA: 205] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 02/21/2015] [Indexed: 12/26/2022]
Abstract
Oleaginous microbes represent an attractive means of converting a diverse range of feedstocks into oils that can be transesterified to biodiesel. However, the mechanism of lipid overproduction in these organisms is incompletely understood, hindering the development of strategies for engineering superior biocatalysts for "single-cell oil" production. In particular, it is unclear which pathways are used to generate the large quantities of NADPH required for overproduction of the highly reduced fatty acid species. While early studies implicated malic enzyme as having a key role in production of lipogenic NADPH in oleaginous fungi, several recent reports have cast doubts as to whether malic enzyme may contribute to production of lipogenic NADPH in the model oleaginous yeast Yarrowia lipolytica. To address this problem we have used (13)C-Metabolic Flux Analysis to estimate the metabolic flux distributions during lipid accumulation in two Y. lipolytica strains; a control strain and a previously published engineered strain capable of producing lipids at roughly twice the yield. We observe a dramatic rearrangement of the metabolic flux distribution in the engineered strain which supports lipid overproduction. The NADPH-producing flux through the oxidative Pentose Phosphate Pathway is approximately doubled in the engineered strain in response to the roughly two-fold increase in fatty acid biosynthesis, while the flux through malic enzyme does not differ significantly between the two strains. Moreover, the estimated rate of NADPH production in the oxidative Pentose Phosphate Pathway is in good agreement with the estimated rate of NADPH consumption in fatty acid biosynthesis in both strains. These results suggest the oxidative Pentose Phosphate Pathway is the primary source of lipogenic NADPH in Y. lipolytica.
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Affiliation(s)
- Thomas M Wasylenko
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Woo Suk Ahn
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Gregory Stephanopoulos
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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Stottmeister U, Behrens U, Weissbrodt E, Barth G, Franke-Rinker D, Schulze E. Nutzung von Paraffinen und anderen Nichtkohlenhydrat-Kohlenstoffquellen zur mikrobiellen Citronensäuresynthese. J Basic Microbiol 2007. [DOI: 10.1002/jobm.19820220608] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Metabolism of alkanes by yeasts. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2005. [DOI: 10.1007/3-540-10464-x_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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Ratledge C, Wynn JP. The biochemistry and molecular biology of lipid accumulation in oleaginous microorganisms. ADVANCES IN APPLIED MICROBIOLOGY 2003; 51:1-51. [PMID: 12236054 DOI: 10.1016/s0065-2164(02)51000-5] [Citation(s) in RCA: 531] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Colin Ratledge
- Lipid Research Centre, Department of Biological Sciences, University of Hull, HU6 7RX, United Kingdom
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Wynn JP, Hamid AA, Li Y, Ratledge C. Biochemical events leading to the diversion of carbon into storage lipids in the oleaginous fungi Mucor circinelloides and Mortierella alpina. MICROBIOLOGY (READING, ENGLAND) 2001; 147:2857-2864. [PMID: 11577164 DOI: 10.1099/00221287-147-10-2857] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The biochemical events associated with the onset of lipid accumulation in Mucor circinelloides and Mortierella alpina, under conditions of nitrogen-limited growth, have been elucidated; they differ in key aspects from those described in oleaginous yeasts. The NAD+:isocitrate dehydrogenases of Mc. circinelloides and Mort. alpina were not absolutely dependent on AMP for activity. Furthermore, changes in the cellular adenine nucleotide pools and energy charge were different from those reported for oleaginous yeasts. In Mc. circinelloides ATP, ADP and AMP concentrations all decreased by 50% after nitrogen limitation, leading to a constant energy charge at the expense of the size of the total adenylate pool. Pyruvate carboxylase in Mc. circinelloides was cytosolic, having implications for the organization of lipid synthesis in filamentous fungi. As a result of the data obtained, a revised and more concerted mechanism for the initiation of storage lipid accumulation is put forward for filamentous fungi.
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Affiliation(s)
- James P Wynn
- Centre for Advanced Lipid Research, Department of Biological Sciences, University of Hull, Hull HU6 7RX, UK1
| | - Adil A Hamid
- Department of Microbiology, Universitii Kebangsaan, Malaysia, 43600 Bangi, Salangor Darul Ehsan, Malaysia2
| | - Yonghua Li
- Centre for Advanced Lipid Research, Department of Biological Sciences, University of Hull, Hull HU6 7RX, UK1
| | - Colin Ratledge
- Centre for Advanced Lipid Research, Department of Biological Sciences, University of Hull, Hull HU6 7RX, UK1
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Antonucci S, Bravi M, Bubbico R, Di Michele A, Verdone N. Selectivity in citric acid production by Yarrowia lipolytica. Enzyme Microb Technol 2001; 28:189-195. [PMID: 11166811 DOI: 10.1016/s0141-0229(00)00288-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This experimental study reports about production selectivity in the fermentation of glucose to citric acid by Yarrowia lipolytica as a function of substrate concentration. Batch runs featuring biomass growth and one or two citric acid production phases were carried out in a 15-l stirred tank fermentor. The presented results demonstrate that working at high initial substrate concentration in the production phase is beneficial both in terms of a higher production rate of citric acid, the desired metabolite (reaching 0.077 h(-1)) and of a higher utilization degree of the employed carbon source (yield up to 0.384 g(c.a.)/g(glucose)). The production rate of isocitric acid, the major undesired metabolite, was found to be practically constant over the tested initial substrate concentration range.
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Affiliation(s)
- S Antonucci
- Dipartimento di Ingegneria Chimica, Università di Roma "La Sapienza", Italy
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Kim H, Mozaffar Z, Weete JD. A dual cofactor-specific isocitrate dehydrogenase from Pythium ultimum. Can J Microbiol 1996; 42:1241-7. [PMID: 8989862 DOI: 10.1139/m96-160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Isocitrate dehydrogenase is considered to be one of the key regulatory enzymes in the conversion of glucose into fatty acids by oleaginous microorganisms. A dual coenzyme-specific isocitrate dehydrogenase (EC 1.1.1.41) (IDH) was isolated from the primitive fungus Pythium ultimum and purified by 211-fold by sequential ion-exchange, affinity, and gel filtration chromatographies. Specific activity of the partially purified enzyme was 76.2 mumol/(min.mg protein) with NAD+ and 40% less active with NADP+. Optimum pH for activity was 8.5-9.5. K(m) values for threo-D-isocitrate and NAD+ were 0.031 and 0.55 mM, respectively. The estimated molecular mass of the IDH was 96 kDa under nondenaturing conditions and 48 kDa under denaturing conditions, suggesting that the enzyme is composed of two subunits of the same size. The enzyme was relatively stable up to 55 degrees C, but no activity was detected after exposure to 65 degrees C for 15 min. Mg2+ or Mn2+ were required for activity.
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Affiliation(s)
- H Kim
- Department of Botany and Microbiology, Alabama Agricultural Experiment Station, Auburn University 36849, USA
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McKay IA, Maddox IS, Brooks JD. High specific rates of glucose utilisation under conditions of restricted growth are required for citric acid accumulation by Yarrowia lipolytica IMK 2. Appl Microbiol Biotechnol 1994. [DOI: 10.1007/bf00166084] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Abstract
The production of organic acids covers two aspects: first, the metabolic pathways involved in the biosynthesis, and, second, the industrial process strategy adopted. The review seeks to show the underlying biochemical similarities in the biosynthesis of organic acids and the resulting similarities in the commercial processes. Two groups of acids are defined, those with a "long" biosynthetic path from glucose, involving much of the glycolytic pathway and the tricarboxylic acid cycle, and those acids with a "short pathway", essentially a biotransformation of glucose. The regulation of the pathways and the future developments in metabolic control theory and genetic manipulations relating to them are considered. The organisms used industrially are also limited, Aspergillus sp. and Candida yeasts; again the underlying metabolic similarities lead to similar strategies for all the acids discussed.
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Affiliation(s)
- M Mattey
- University of Strathclyde in Glasgow, Department of Bioscience and Biotechnology, Scotland
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Finogenova TV, Shishkanova NV, Fausek EA, Eremina SS. Biosynthesis of isocitric acid from ethanol by yeasts. Appl Microbiol Biotechnol 1991. [DOI: 10.1007/bf00164426] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Evans CT, Ratledget C. The Physiological Significance of Citric Acid in the Control of Metabolism in Lipid-Accumulating Yeasts. Biotechnol Genet Eng Rev 1985. [DOI: 10.1080/02648725.1985.10647818] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Evans CT, Scragg AH, Ratledge C. Regulation of citrate efflux from mitochondria of oleaginous and non-oleaginous yeasts by adenine nucleotides. EUROPEAN JOURNAL OF BIOCHEMISTRY 1983; 132:609-15. [PMID: 6682758 DOI: 10.1111/j.1432-1033.1983.tb07407.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The regulation of mitochondrial citrate metabolism has been investigated in oleaginous and non-oleaginous yeasts to ascertain its importance in controlling the rate of citrate efflux from mitochondria. The following observations were made: 1. Citrate efflux from mitochondria of the oleaginous yeast Candida curvata D, in the presence of L-malate and pyruvate, was stimulated by adding ATP and reduced by AMP. In the non-oleaginous yeast, Candida utilis 359, there was very little stimulation of citrate efflux by ATP but it was reduced by AMP. These effects appeared to be generalized as similar results were obtained in an examination of eight further yeasts (seven oleaginous and one non-oleaginous). 2. The effects of ATP and AMP were not observed in mitochondria whose metabolism had been inhibited by antimycin A and rotenone indicating the direct regulation of the citrate translocase was not involved. 3. In C. curvata D, ATP increased the total mitochondrial citrate content and reduced that of 2-oxoglutarate whereas AMP had the reverse effect. In C. utilis 359, AMP had a similar effect but that of ATP was much smaller. 4. To explain these observations the mitochondrial NAD+-dependent isocitrate dehydrogenase was studied in a number of yeasts. The enzyme from oleaginous yeasts had a requirement for AMP for activity and was inhibited by ATP. In non-oleaginous yeasts the enzyme was active in the absence of AMP and increased in activity as the isocitrate concentration increased. 5. The enzyme in C. curvata D was constantly more sensitive to increasing energy charge than that of the non-oleaginous yeast. These results indicate that the supply of citrate (and hence acetyl-CoA) to the cytosol is controlled by the activity of the intramitochondrial NAD+-dependent isocitrate dehydrogenase which in turn is regulated by adenine nucleotides. The sensitivity of this enzyme to the ATP/AMP ratio during lipogenesis is therefore an important control in the accumulation of lipid by yeasts.
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Evans CT, Scragg AH, Ratledge C. A comparative study of citrate efflux from mitochondria of oleaginous and non-oleaginous yeasts. EUROPEAN JOURNAL OF BIOCHEMISTRY 1983; 130:195-204. [PMID: 6825688 DOI: 10.1111/j.1432-1033.1983.tb07136.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Stottmeister U, Behrens U, Weissbrodt E, Barth G, Franke-Rinker D, Schulze E. [Utilization of paraffins and other noncarbohydrate carbon sources for microbial citric acid synthesis]. ZEITSCHRIFT FUR ALLGEMEINE MIKROBIOLOGIE 1982; 22:399-424. [PMID: 6753364 DOI: 10.1002/jobm.3630220608] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
This article reviews the developments achieved in citrate and isocitrate accumulation with non-carbohydrate substrates by microorganisms presented as well in academic publications as in patients. The efficiency of citrate and isocitrate overproducing microorganisms and of mutants obtained thereof with respect to different carbon sources (n-alkanes, triglycerides, organic acids, etc.) is discussed. The influence of environmental conditions (media, pH etc.) and biochemical mechanisms which lead to metabolic overflow are emphasized. The kinetics of fermentation processes are described, calculations concerning carbon balances are involved. The production of by-products and the conversion of isocitrate to citrate is considered. The production of citric acid by yeasts which utilize different carbon sources may be economically feasible and an accession to the practized molasse-Aspergillus-process.
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Bartels PD, Jensen PK. Role of AMP in regulation of the citric acid cycle in mitochondria from baker's yeast. BIOCHIMICA ET BIOPHYSICA ACTA 1979; 582:246-59. [PMID: 367447 DOI: 10.1016/0304-4165(79)90388-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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