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Zapata-Restrepio LM, Hauton C, Hudson MD, Williams ID, Hauton D. Toxicity of tributyltin to the European flat oyster Ostrea edulis: Metabolomic responses indicate impacts to energy metabolism, biochemical composition and reproductive maturation. PLoS One 2023; 18:e0280777. [PMID: 36745593 PMCID: PMC9901812 DOI: 10.1371/journal.pone.0280777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 01/10/2023] [Indexed: 02/07/2023] Open
Abstract
Tri-Butyl Tin (TBT) remains as a legacy pollutant in the benthic environments. Although the toxic impacts and endocrine disruption caused by TBT to gastropod molluscs have been established, the changes in energy reserves allocated to maintenance, growth, reproduction and survival of European oysters Ostrea edulis, a target species of concerted benthic habitat restoration projects, have not been explored. This study was designed to evaluate the effect of TBT chloride (TBTCl) on potential ions and relevant metabolomic pathways and its association with changes in physiological, biochemical and reproductive parameters in O. edulis exposed to environmental relevant concentrations of TBTCl. Oysters were exposed to TBTCl 20 ng/L (n = 30), 200 ng/L (n = 30) and 2000 ng/L (n = 30) for nine weeks. At the end of the exposure, gametogenic stage, sex, energy reserve content and metabolomic profiling analysis were conducted to elucidate the metabolic alterations that occur in individuals exposed to those compounds. Metabolite analysis showed significant changes in the digestive gland biochemistry in oysters exposed to TBTCl, decreasing tissue ATP concentrations through a combination of the disruption of the TCA cycle and other important molecular pathways involved in homeostasis, mitochondrial metabolism and antioxidant response. TBTCl exposure increased mortality and caused changes in the gametogenesis with cycle arrest in stages G0 and G1. Sex determination was affected by TBTCl exposure, increasing the proportion of oysters identified as males in O. edulis treated at 20ng/l TBTCl, and with an increased proportion of inactive stages in oysters treated with 2000 ng/l TBTCl. The presence and persistence of environmental pollutants, such as TBT, could represent an additional threat to the declining O. edulis populations and related taxa around the world, by increasing mortality, changing reproductive maturation, and disrupting metabolism. Our findings identify the need to consider additional factors (e.g. legacy pollution) when identifying coastal locations for shellfish restoration.
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Affiliation(s)
- Lina M. Zapata-Restrepio
- School of Geography and Environmental Sciences, University of Southampton, Highfield Campus, Southampton, United Kingdom
- * E-mail:
| | - Chris Hauton
- Ocean and Earth Sciences, National Oceanography Centre, University of Southampton, Southampton, Hampshire, United Kingdom
| | - Malcolm D. Hudson
- School of Geography and Environmental Sciences, University of Southampton, Highfield Campus, Southampton, United Kingdom
| | - Ian D. Williams
- Faculty of Engineering and Physical Sciences, University of Southampton, Highfield Campus, Southampton, United Kingdom
| | - David Hauton
- Metabolomics Research Group, Chemistry Research Laboratory, University of Oxford, Oxford, United Kingdom
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2
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Somasundaram S, Jeong J, Irisappan G, Kim TW, Hong SH. Enhanced Production of Malic Acid by Co-localization of Phosphoenolpyruvate Carboxylase and Malate Dehydrogenase Using Synthetic Protein Scaffold in Escherichia coli. BIOTECHNOL BIOPROC E 2020. [DOI: 10.1007/s12257-019-0269-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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3
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Prajongtat P, Phromyothin DST, Hannongbua S. Key role of hydrazine to the interaction between oxaloacetic against phosphoenolpyruvic carboxykinase (PEPCK): ONIOM calculations. J Mol Model 2013; 19:3165-74. [DOI: 10.1007/s00894-013-1842-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Accepted: 04/01/2013] [Indexed: 11/24/2022]
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Abstract
This review aims to discuss the varied types of inhibitors of biotin-dependent carboxylases, with an emphasis on the inhibitors of pyruvate carboxylase. Some of these inhibitors are physiologically relevant, in that they provide ways of regulating the cellular activities of the enzymes e.g. aspartate and prohibitin inhibition of pyruvate carboxylase. Most of the inhibitors that will be discussed have been used to probe various aspects of the structure and function of these enzymes. They target particular parts of the structure e.g. avidin - biotin, FTP - ATP binding site, oxamate - pyruvate binding site, phosphonoacetate - binding site of the putative carboxyphosphate intermediate.
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Affiliation(s)
- Tonya N Zeczycki
- Department of Biochemistry, University of Wisconsin, Madison, WI 53726, USA
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5
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Harris DM, Westerlaken I, Schipper D, van der Krogt ZA, Gombert AK, Sutherland J, Raamsdonk LM, van den Berg MA, Bovenberg RAL, Pronk JT, Daran JM. Engineering of Penicillium chrysogenum for fermentative production of a novel carbamoylated cephem antibiotic precursor. Metab Eng 2009; 11:125-37. [PMID: 19271269 DOI: 10.1016/j.ymben.2008.12.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Penicillium chrysogenum was successfully engineered to produce a novel carbamoylated cephalosporin that can be used as a synthon for semi-synthetic cephalosporins. To this end, genes for Acremonium chrysogenum expandase/hydroxylase and Streptomyces clavuligerus carbamoyltransferase were expressed in a penicillinG high-producing strain of P.chrysogenum. Growth of the engineered strain in the presence of adipic acid resulted in production of adipoyl-7-amino-3-carbamoyloxymethyl-3-cephem-4-carboxylic acid (ad7-ACCCA) and of several adipoylated pathway intermediates. A combinatorial chemostat-based transcriptome study, in which the ad7-ACCCA-producing strain and a strain lacking key genes in beta-lactam synthesis were grown in the presence and absence of adipic acid, enabled the dissection of transcriptional responses to adipic acid per se and to ad7-ACCCA production. Transcriptome analysis revealed that adipate catabolism in P.chrysogenum occurs via beta-oxidation and enabled the identification of putative genes for enzymes involved in mitochondrial and peroxisomal beta-oxidation pathways. Several of the genes that showed a specifically altered transcript level in ad7-ACCCA-producing cultures were previously implicated in oxidative stress responses.
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Affiliation(s)
- Diana M Harris
- Department of Biotechnology, Delft University of Technology, The Netherlands
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6
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Awaya JD, Tittabutr P, Li QX, Borthakur D. Pyruvate carboxylase is involved in metabolism of mimosine by Rhizobium sp. strain TAL1145. Arch Microbiol 2008; 190:409-15. [PMID: 18493742 DOI: 10.1007/s00203-008-0384-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2007] [Revised: 03/03/2008] [Accepted: 04/29/2008] [Indexed: 11/29/2022]
Abstract
The objective of this study was to determine the role of midK, which encodes a protein similar to pyruvate carboxylase, in mimosine degradation by Rhizobium sp. strain TAL1145. The midK gene is located downstream of midR in the cluster of genes for mimosine degradation in Rhizobium sp. strain TAL1145. The midK mutants of TAL1145 degraded mimosine slower than the wild-type. These mutants could utilize pyruvate as a source of carbon, indicating that there is another pyruvate carboxylase (pyc) gene in TAL1145. Two classes of clones were isolated from the library of TAL1145 by complementing a pyc mutant of Rhizobium etli, one class contained midK, while the other carried pyc. Both midK and pyc of TAL1145 complemented the midK mutant for mimosine degradation, and also the R. etli pyc mutant for pyruvate utilization. The midK-encoded pyruvate carboxylase was required for an efficient conversion of mimosine into 3-hydroxy-4-pyridone (HP).
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Affiliation(s)
- Jonathan D Awaya
- Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, 1955 East-West Road, Ag. Science 218, Honolulu, HI 96822, USA
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7
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A. Osmani S, C. Scrutton M. Activation of pyruvate carboxylase from aspergillus nidulans
by acetyl coenzyme A. FEBS Lett 2001. [DOI: 10.1016/0014-5793(81)80794-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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8
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Serkova N, Jacobsen W, Niemann CU, Litt L, Benet LZ, Leibfritz D, Christians U. Sirolimus, but not the structurally related RAD (everolimus), enhances the negative effects of cyclosporine on mitochondrial metabolism in the rat brain. Br J Pharmacol 2001; 133:875-85. [PMID: 11454661 PMCID: PMC1572850 DOI: 10.1038/sj.bjp.0704142] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2000] [Revised: 03/19/2001] [Accepted: 04/30/2001] [Indexed: 01/16/2023] Open
Abstract
Clinical studies have shown enhancement of cyclosporine toxicity when co-administered with the immunosuppressant sirolimus. We evaluated the biochemical mechanisms underlying the sirolimus/cyclosporine interaction on rat brain metabolism using magnetic resonance spectroscopy (MRS) and compared the effects of sirolimus with those of the structurally related RAD. Two-week-old rats (25 g) were allocated to the following treatment groups (all n=6): I. control, II. cyclosporine (10 mg kg(-1) d(-1)), III. sirolimus (3 mg kg(-1) d(-1)), IV. RAD (3 mg kg(-1) d(-1)), V. cyclosporine+sirolimus and VI. cyclosporine+RAD. Drugs were administered by oral gavage for 6 days. Twelve hours after the last dose, metabolic changes were assessed in brain tissue extracts using multinuclear MRS. Cyclosporine significantly inhibited mitochondrial glucose metabolism (glutamate: 78+/-6% of control; GABA: 67+/-12%; NAD(+): 76+/-3%; P<0.05), but increased lactate production. Sirolimus and RAD inhibited cytosolic glucose metabolism via lactate production (sirolimus: 81+/-3% of control, RAD: 69+/-2%; P<0.02). Sirolimus enhanced cyclosporine-induced inhibition of mitochondrial glucose metabolism (glutamate: 60+/-4%; GABA: 59+/-8%; NAD(+): 45+/-5%; P<0.02 versus cyclosporine alone). Lactate production was significantly reduced. In contrast, RAD antagonized the effects of cyclosporine (glutamate, GABA, and NAD(+), not significantly different from controls). The results can partially be explained by pharmacokinetic interactions: co-administration increased the distribution of cyclosporine and sirolimus into brain tissue, while co-administration with RAD decreased cyclosporine brain tissue concentrations. In addition RAD, but not sirolimus, distributed into brain mitochondria. The combination of cyclosporine/RAD compares favourably to cyclosporine/sirolimus in regards to their effects on brain high-energy metabolism and tissue distribution in the rat.
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Affiliation(s)
- Natalie Serkova
- Department of Biopharmaceutical Sciences, University of California, San Francisco, California, CA 94143, U.S.A
- Institut für Biologie/Chemie, Universität Bremen, 28359 Bremen, Germany
| | - Wolfgang Jacobsen
- Department of Biopharmaceutical Sciences, University of California, San Francisco, California, CA 94143, U.S.A
| | - Claus U Niemann
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, California, CA 94143, U.S.A
| | - Lawrence Litt
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, California, CA 94143, U.S.A
| | - Leslie Z Benet
- Department of Biopharmaceutical Sciences, University of California, San Francisco, California, CA 94143, U.S.A
| | - Dieter Leibfritz
- Institut für Biologie/Chemie, Universität Bremen, 28359 Bremen, Germany
| | - Uwe Christians
- Department of Biopharmaceutical Sciences, University of California, San Francisco, California, CA 94143, U.S.A
- Department of Anesthesiology, University of Colorado Health Sciences Center, Denver, Colorado, CO 80262, U.S.A
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9
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Huet C, Menendez J, Gancedo C, François JM. Regulation of pyc1 encoding pyruvate carboxylase isozyme I by nitrogen sources in Saccharomyces cerevisiae. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:6817-23. [PMID: 11082192 DOI: 10.1046/j.1432-1033.2000.01779.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In Saccharomyces cerevisiae, the existence of PYC1 and PYC2 encoding cytosolic pyruvate carboxylase isoform I and II is rather puzzling, owing to the lack of potent differential gene regulation by the carbon sources. We report several findings indicating that these two genes are differentially regulated by the nature of the nitrogen source. In wild-type cells, the activity of pyruvate carboxylase, which is the sum of pyruvate carboxylase isoform I and II, was two- to fivefold lower in carbon medium containing aspartate, asparagine, glutamate or glutamine instead of ammonium as the nitrogen source, whereas it was 1.5- to threefold higher when the ammonium source was substituted by arginine, methionine, threonine or leucine. These enzymatic changes were independent of the nature of the carbon source and closely correlated to the changes in beta-galactosidase from PYC1-lacZ gene fusion and in PYC1 transcripts. Transfer of exponentially growing cells of the pyc2 mutant from an aspartate or a glutamate medium to an ammonium medium caused a fivefold increase in PYC1 mRNA in less than 30 min, whereas in the inverse experiment, PYC1 transcripts returned within 30 min to the low levels found in aspartate/glutamate medium. By contrast, these conditions affected neither the pyruvate carboxylase activity encoded by PYC2 nor PYC2 mRNA. Considering that changes in PYC1 expression inversely correlated with changes in alpha-ketoglutarate concentration or in alpha-ketoglutarate/glutamate ratio following the nitrogen shift experiments, and taking into account the pivotal role of this metabolite in ammonium assimilation, it is suggested that changes in alpha-ketoglutarate or in the alpha-ketoglutarate/glutamate ratio might be implicated in triggering the nitrogen effects on PYC1 expression. The physiological significance of the differential sensitivity of PYC1 and PYC2 genes with respect to the nitrogen source in the growth medium is also discussed.
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Affiliation(s)
- C Huet
- Centre de Bioingénierie Gilbert Durand, Toulouse,France
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10
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Bauer J, Luttik MA, Flores CL, van Dijken JP, Pronk JT, Niederberger P. By-product formation during exposure of respiring Saccharomyces cerevisiae cultures to excess glucose is not caused by a limited capacity of pyruvate carboxylase. FEMS Microbiol Lett 1999; 179:107-13. [PMID: 10481094 DOI: 10.1111/j.1574-6968.1999.tb08715.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Upon exposure to excess glucose, respiring cultures of Saccharomyces cerevisiae produce substantial amounts of ethanol and acetate. A possible role of a limited anaplerotic capacity in this process was investigated by overexpressing pyruvate carboxylase and by replacing it with a heterologous enzyme (Escherichia coli phosphoenolpyruvate carboxylase). Compared to the wild-type, neither the pyruvate carboxylase (Pyc)-overexpressing nor the transgenic strain exhibited reduced by-product formation after glucose pulses to aerobic glucose-limited chemostat cultures. An increased intracellular malate concentration was observed in the two engineered strains. It is concluded that by-product formation in S. cerevisiae is not caused by a limited anaplerotic capacity.
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Affiliation(s)
- J Bauer
- Lesaffre Développement, P.O. Box 6027, 147, rue Gabriel Péri, 59706, Marcq en Baroeul, France
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11
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Abstract
Rhizobia are a diverse group of Gram-negative bacteria comprised of the genera Rhizobium, Bradyrhizobium, Mesorhizobium, Sinorhizobium and Azorhizobium. A unifying characteristic of the rhizobia is their capacity to reduce (fix) atmospheric nitrogen in symbiotic association with a compatible plant host. Symbiotic nitrogen fixation requires a substantial input of energy from the rhizobial symbiont. This review focuses on recent studies of rhizobial carbon metabolism which have demonstrated the importance of a functional tricarboxylic acid (TCA) cycle in allowing rhizobia to efficiently colonize the plant host and/or develop an effective nitrogen fixing symbiosis. Several anaplerotic pathways have also been shown to maintain TCA cycle activity under specific conditions. Biochemical and physiological characterization of carbon metabolic mutants, along with the analysis of cloned genes and their corresponding gene products, have greatly advanced our understanding of the function of enzymes such as citrate synthase, oxoglutarate dehydrogenase, pyruvate carboxylase and malic enzymes. However, much remains to be learned about the control and function of these and other key metabolic enzymes in rhizobia.
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Affiliation(s)
- M F Dunn
- Departamento de Ecología Molecular, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico.
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12
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Abstract
Pyruvate carboxylase (PYC) is a biotin-dependent enzyme catalyzing the anaplerotic conversion of pyruvate to oxaloacetate in Rhizobium etli strain CE3. A pyc::Tn5 mutant had severely reduced growth, or failed to grow on sugars, three-carbon organic acids or glycerol, consistent with these substrates being metabolized via pyruvate. Transconjugants expressing a pyc::beta-glucuronidase gene fusion had slightly increased apparent pyc transcription during growth on pyruvate as compared to succinate, similar to the modest carbon source dependent changes in PYC activity reported previously. Biotin supplementation of cultures growing on pyruvate dramatically increased PYC activity but not apparent pyc transcription. Bacteroids isolated from bean nodules did not contain detectable PYC activity while apparent pyc transcription occurred at a moderate level.
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Affiliation(s)
- M F Dunn
- Departamento de Ecología Molecular, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico.
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13
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Flores CL, Gancedo C. Expression of PEP carboxylase from Escherichia coli complements the phenotypic effects of pyruvate carboxylase mutations in Saccharomyces cerevisiae. FEBS Lett 1997; 412:531-4. [PMID: 9276461 DOI: 10.1016/s0014-5793(97)00854-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We investigated the effects of the expression of the Escherichia coli ppc gene encoding PEP carboxylase in Saccharomyces cerevisiae mutants devoid of pyruvate carboxylase. Functional expression of the ppc gene restored the ability of the yeast mutants to grow in glucose-ammonium medium. Growth yield in this medium was the same in the transformed yeast than in the wild type although the growth rate of the transformed yeast was slower. Growth in pyruvate was slowed down in the transformed strain, likely due to a futile cycle produced by the simultaneous action of PEP carboxykinase and PEP carboxylase.
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Affiliation(s)
- C L Flores
- Instituto de Investigaciones Biomédicas, Unidad de Bioquimica y Genética de Levaduras, Madrid, Spain
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15
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Abstract
In yeasts, pyruvate is located at a major junction of assimilatory and dissimilatory reactions as well as at the branch-point between respiratory dissimilation of sugars and alcoholic fermentation. This review deals with the enzymology, physiological function and regulation of three key reactions occurring at the pyruvate branch-point in the yeast Saccharomyces cerevisiae: (i) the direct oxidative decarboxylation of pyruvate to acetyl-CoA, catalysed by the pyruvate dehydrogenase complex, (ii) decarboxylation of pyruvate to acetaldehyde, catalysed by pyruvate decarboxylase, and (iii) the anaplerotic carboxylation of pyruvate to oxaloacetate, catalysed by pyruvate carboxylase. Special attention is devoted to physiological studies on S. cerevisiae strains in which structural genes encoding these key enzymes have been inactivated by gene disruption.
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Affiliation(s)
- J T Pronk
- Department of Microbiology an Enzymology, Kluyver Laboratory of Biotechnology, Delft University of Technology, The Netherlands
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16
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Dunn MF, Encarnación S, Araíza G, Vargas MC, Dávalos A, Peralta H, Mora Y, Mora J. Pyruvate carboxylase from Rhizobium etli: mutant characterization, nucleotide sequence, and physiological role. J Bacteriol 1996; 178:5960-70. [PMID: 8830693 PMCID: PMC178453 DOI: 10.1128/jb.178.20.5960-5970.1996] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Pyruvate carboxylase (PYC), a biotin-dependent enzyme which catalyzes the conversion of pyruvate to oxaloacetate, was hypothesized to play an important anaplerotic role in the growth of Rhizobium etli during serial subcultivation in minimal media containing succinate (S. Encarnación, M. Dunn, K. Willms, and J. Mora, J. Bacteriol. 177:3058-3066, 1995). R. etli and R. tropici pyc::Tn5-mob mutants were selected for their inability to grow in minimal medium with pyruvate as a sole carbon source. During serial subcultivation in minimal medium containing 30 mM succinate, the R. etli parent and pyc mutant strains exhibited similar decreases in growth rate with each subculture. Supplementation of the medium with biotin prevented the growth decrease of the parent but not the mutant strain, indicating that PYC was necessary for the growth of R. etli under these conditions. The R. tropici pyc mutant grew normally in subcultures regardless of biotin supplementation. The symbiotic phenotypes of the pyc mutants from both species were similar to those of the parent strains. The R. etli pyc was cloned, sequenced, and found to encode a 126-kDa protein of 1,154 amino acids. The deduced amino acid sequence is highly homologous to other PYC sequences, and the catalytic domains involved in carboxylation, pyruvate binding, and biotinylation are conserved. The sequence and biochemical data show that the R. etli PYC is a member of the alpha4, homotetrameric, acetyl coenzyme A-activated class of PYCs.
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Affiliation(s)
- M F Dunn
- Departamento de Ecología Molecular, Centro de Investigación sobre Fijación de Nitrógeno, Universidad Nacional Autónoma de México, Cuernavaca, Morelos.
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17
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Blázquez MA, Gamo FJ, Gancedo C. A mutation affecting carbon catabolite repression suppresses growth defects in pyruvate carboxylase mutants from Saccharomyces cerevisiae. FEBS Lett 1995; 377:197-200. [PMID: 8543050 DOI: 10.1016/0014-5793(95)01337-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Yeasts with disruptions in the genes PYC1 and PYC2 encoding the isoenzymes of pyruvate carboxylase cannot grow in a glucose-ammonium medium (Stucka et al. (1991) Mol. Gen. Genet. 229, 307-315). We have isolated a dominant mutation, BPC1-1, that allows growth in this medium of yeasts with interrupted PYC1 and PYC2 genes. The BPC1-1 mutation abolishes catabolite repression of a series of genes and allows expression of the enzymes of the glyoxylate cycle during growth in glucose. A functional glyoxylate cycle is necessary for suppression as a disruption of gene ICL1 encoding isocitrate lyase abolished the phenotypic effect of BPC1-1 on growth in glucose-ammonium. Concurrent expression from constitutive promoters of genes ICL1 and MLS1 (encoding malate synthase) also suppressed the growth phenotype of pyc1 pyc2 mutants. The mutation BPC1-1 is either allelic or closely linked to the mutation DGT1-1.
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Affiliation(s)
- M A Blázquez
- Instituto de Investigaciones Biomédicas del C.S.I.C., Unidad de Bioquímica y Genética de Levaduras, Madrid, Spain
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18
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Abstract
Strains of Rhizobium etli, Rhizobium meliloti, and Rhizobium tropici decreased their capacity to grow after successive subcultures in minimal medium, with a pattern characteristic for each species. During the growth of R. etli CE 3 in minimal medium (MM), a fermentation-like response was apparent: the O2 content was reduced and, simultaneously, organic acids and amino acids were excreted and poly-beta-hydroxybutyrate (PHB) was accumulated. Some of the organic acids excreted into the medium were tricarboxylic acid (TCA) cycle intermediates, and, concomitantly, the activities of several TCA cycle and auxiliary enzymes decreased substantially or became undetectable. Optimal and sustained growth and a low PHB content were found in R. etli CE 3 when it was grown in MM inoculated at a low cell density with O2 maintained at 20% or with the addition of supplements that have an effect on the supply of substrates for the TCA cycle. In the presence of supplements such as biotin or thiamine, no amino acids were excreted and the organic acids already excreted into the medium were later reutilized. Levels of enzyme activities in cells from supplemented cultures indicated that carbon flux through the TCA cycle was maintained, which did not happen in MM. It is proposed that the fermentative state in Rhizobium species is triggered by a cell density signal that results in the regulation of some of the enzymes responsible for the flux of carbon through the TCA cycle and that this in turn determines how much carbon is available for the synthesis and accumulation of PHB. The fermentative state of free-living Rhizobium species may be closely related to the metabolism that these bacteria express during symbiosis.
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Affiliation(s)
- S Encarnación
- Departamento de Ecología Molecular, Universidad Nacional Autónoma de México, Cuernavaca, Morelos
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Charles AM, Sykora Y. Purification and characterization of the phosphoenolpyruvate carboxylase from the facultative chemolithotroph Thiobacillus novellus (ATCC 8093). Antonie Van Leeuwenhoek 1992; 62:155-65. [PMID: 1416912 DOI: 10.1007/bf00582575] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Phosphoenolpyruvate carboxylase (EC4.1.1.31), which catalyzes the carboxylation of phosphoenolpyruvate to produce oxaloacetate was purified 465-fold from extracts of organotrophically grown Thiobacillus novellus. Nondenaturing polyacrylamide gel electrophoresis (PAGE) of the purified enzyme revealed the presence of two bands after staining with Buffalo Black. Gels stained with Fast Violet B after incubation with PEP, HCO3-, Mg2+ and acetyl CoA also showed two bands of activity with the faster moving the more active of the two. Sodium dodecylsulfate (SDS)-PAGE of the enzyme heated at 100 degrees C for 5 min revealed the presence of three intensely stained bands of M(r) 95 K, 51 K, and 28 K. However, electrophoresis of the enzyme heated for 2 min showed a single band of about 100 K, indicating that the preparation was likely homogeneous. The 51 K and 28 K subunits are thus products of the 95 K subunit. Gel filtration studies of the native enzyme yielded a M(r) of 360 K. Therefore, the enzyme is a tetramer. The optimum pH in Tris buffer was 8.0, with Km for PEP 0.64 mM, HCO3- 0.11 mM, and acetyl CoA a potent activator, 1.3 microM. A divalent cation best served by Mg2+ gave sigmoidal initial velocity plots. Hill plots of the data gave coefficients (nH) of 2.6. None of the metabolites tested, nucleotide triophosphates excepted, significantly affected enzyme activity. Binding studies with 14C-labelled PEP revealed the binding of about 20 moles PEP per mole (360,000 g) of PEPC. Initial velocity studies suggest that the reaction is catalyzed by a random Bi Bi mechanism. Despite the lack of inhibition by certain metabolites, the enzyme's function is probably anaplerotic.
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Affiliation(s)
- A M Charles
- Department of Biology, University of Waterloo, Ontario, Canada
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20
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Stucka R, Dequin S, Salmon JM, Gancedo C. DNA sequences in chromosomes II and VII code for pyruvate carboxylase isoenzymes in Saccharomyces cerevisiae: analysis of pyruvate carboxylase-deficient strains. MOLECULAR & GENERAL GENETICS : MGG 1991; 229:307-15. [PMID: 1921979 DOI: 10.1007/bf00272171] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A gene encoding pyruvate carboxylase has previously been isolated from Saccharomyces cerevisiae. We have isolated a second gene, PYC2, from the same organism also encoding a pyruvate carboxylase. The gene PYC2 is situated on the right arm of chromosome II between the DUR 1, 2 markers and the telomere. We localized the previously isolated gene, which we designate PYC1, to chromosome VII. Disruption of either of the genes did not produce marked changes in the phenotype. However, simultaneous disruption of both genes resulted in inability to grow on glucose as sole carbon source, unless aspartate was added to the medium. This indicates that in wild-type yeast there is no bypass for the reaction catalysed by pyruvate carboxylase. The coding regions of both genes exhibit a homology of 90% at the amino acid level and 85% at the nucleotide level. No appreciable homology was found in the corresponding flanking regions. No differences in the Km values for ATP or pyruvate were observed between the enzymes obtained from strains carrying inactive, disrupted versions of one or other of the genes.
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Affiliation(s)
- R Stucka
- Institut für Physiologische Chemie, Biochemie und Zellbiologie, Universität, München, Federal Republic of Germany
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Osmani SA, Scrutton MC. The sub-cellular localisation and regulatory properties of pyruvate carboxylase from Rhizopus arrhizus. EUROPEAN JOURNAL OF BIOCHEMISTRY 1985; 147:119-28. [PMID: 3971971 DOI: 10.1111/j.1432-1033.1985.tb08727.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cell-free extracts of Rhizopus arrhizus contain exclusively cytosolic pyruvate carboxylase and NAD-glutamate dehydrogenase, a single mitochondrial isoenzyme of NADP-isocitrate dehydrogenase, and both mitochondrial and cytosolic isoenzymes of NADP-malate dehydrogenase (decarboxylating). Other enzymes examined have sub-cellular localisations similar to those characteristic of mammalian liver. Purified preparations of R. arrhizus pyruvate carboxylase are subject to partial regulatory inhibition by L-aspartate and 2-oxoadipate. L-Glutamate acts as a less effective analogue of L-aspartate while 2-oxoglutarate is ineffective. Competition studies indicate the presence of separate inhibitory sites for L-aspartate and 2-oxoadipate. Under routine assay conditions R. arrhizus pyruvate carboxylase shows significant activation by acyl derivatives of coenzyme A with long chain acyl CoA being more effective than acetyl-CoA. This activation is no longer observed in the presence of high concentrations of pyruvate, MgATP2- and HCO-3. The concentrations of L-aspartate and 2-oxoadipate required to give 50% inhibition ([I]0.5), and the maximal extents of inhibition, are increased by addition of acetyl-CoA. Acetyl-CoA increases the sigmoidal character of the relationship: initial rate/[L-aspartate], but decreases this parameter for the relationship: initial rate/[2-oxoadipate]. The studies indicate that R. arrhizus possesses an entirely cytosolic pathway for the conversion of glucose to fumaric acid and that both the organisation of pyruvate metabolism and the regulation of pyruvate carboxylase differ significantly in this organism as compared to that proposed previously for Aspergillus nidulans.
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Abstract
Phosphoenolpyruvate (PEP) carboxykinase was identified to be the only C3-carboxylating enzyme in Alcaligenes eutrophus. The enzyme requires GDP or inosine diphosphate (GTP or inosine triphosphate) for activity. Pyruvate- and other PEP-dependent CO2-fixing enzyme activities were not detected, regardless of whether the cells were grown autotrophically or heterotrophically. It is suggested that two pathways are present in the organism for the formation of PEP from C4 dicarboxylic acids. Besides decarboxylation of oxaloacetate by PEP carboxykinase, the consecutive action of NADP+-malic enzyme and PEP synthetase can also accomplish this synthesis. An oxaloacetate decarboxylase activity observed in the cell extracts may also contribute to the latter route. The properties of a mutant deficient in PEP synthetase supported the biochemical data. This mutant was unable to grow on pyruvate or lactate and grew slower than the wild type on direct or indirect metabolites of the tricarboxylic acid cycle such as succinate, glutamate, or acetate. Growth on fructose and autotrophic growth were not affected by the enzyme defect. The findings suggest that, depending on the growth substrate utilized, PEP carboxykinase can serve a dual physiological function in A. eutrophus, an anaplerotic function in oxaloacetate synthesis from PEP, or a gluconeogenic function in PEP synthesis from oxaloacetate.
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Taegtmeyer H. Six blind men explore an elephant: aspects of fuel metabolism and the control of tricarboxylic acid cycle activity in heart muscle. Basic Res Cardiol 1984; 79:322-36. [PMID: 6477383 DOI: 10.1007/bf01908033] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Many aspects of the interactions of energy providing substrates and the operational control of the tricarboxylic acid cycle are still unclear. This statement is well supported by the sometimes conflicting observations in heart muscle. The paper discusses some of the knowns and unknowns of tricarboxylic acid cycle regulation and discusses mechanisms of metabolite accumulation in this tissue. It is concluded that the data available at this time are insufficient to propose a unifying concept.
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Taegtmeyer H. On the inability of ketone bodies to serve as the only energy providing substrate for rat heart at physiological work load. Basic Res Cardiol 1983; 78:435-50. [PMID: 6626122 DOI: 10.1007/bf02070167] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The aim of this work was to establish the reasons why ketone bodies, although readily oxidized, do not sustain a physiological work output of the isolated rat heart for more than 30 to 45 min (Taegtmeyer, H., et al., Biochem. J. 186, 701-711 (1980)). First, it was found that the addition of glucose or of asparagine increased the rate of acetoacetate removal by 52 and 77% respectively, and availability of oxaloacetate was one factor limiting the oxidation of acetoacetate. Second, in freeze clamped hearts perfusion with acetoacetate alone caused an increase in the tissue content of acetyl-CoA, citrate, 2-oxoglutarate and glutamate but no change in malate and a decrease in aspartate when compared with glucose as substrate. The changes of aspartate and glutamate exceeded those of 2-oxoglutarate forty times. This means that oxaloacetate formed from aspartate must have passed through the stages of the citric acid cycle to form glutamate and that there was an inhibition of the 2-oxoglutarate dehydrogenase reaction. Third, in hearts perfused with acetoacetate and propionate the accumulation of glutamate and 2-oxoglutarate as well as the decrease in aspartate were associated with a sharp drop in CoASH from 0.258 to 0.093 mumol/g dry wt. This indicates that the accumulation of CoA thioesters left insufficient mitochondrial CoASH for the 2-oxoglutarate dehydrogenase reaction. Fourth, in contrast to acetoacetate cardiac function was unimpaired with acetate plus glucose. With these substrates citrate, 2-oxoglutarate, malate and aspartate all accumulated, either due to formation of oxaloacetate by pyruvate carboxylase or transamination of glutamate with pyruvate. It appears that the changes in cardiac performance and metabolism caused by acetoacetate can be explained by a relative inhibition of the citric acid cycle at the level of 2-oxoglutarate dehydrogenase. The hypothesis is advanced that this might be due to a shortage of intramitochondrial free [CoASH], but the exact mechanism of this inhibition awaits further elucidation.
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Osmani SA, Marston FA, Selmes IP, Chapman AG, Scrutton MC. Pyruvate carboxylase from Aspergillus nidulans. Regulatory properties. EUROPEAN JOURNAL OF BIOCHEMISTRY 1981; 118:271-8. [PMID: 7026241 DOI: 10.1111/j.1432-1033.1981.tb06396.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Pays AG, Jones R, Wilkins MB, Fewson CA, Malcolm AD. Kinetic analysis of effectors of phosphoenolpyruvate carboxylase from Bryophyllum fedtschenkoi. BIOCHIMICA ET BIOPHYSICA ACTA 1980; 614:151-62. [PMID: 7397199 DOI: 10.1016/0005-2744(80)90176-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The activity of phosphoenolpyruvate carboxylase (orthophosphate:oxaloacetate carboxy-lyase (phosporylating) EC 4.1.1.31) purified from Bryophyllum fedtschenkoi has been measured in the presence of various concentrations of phosphoenolpyruvate, L-malate and glucose 6-phosphate. At high pH, the enzyme is competitively inhibited by L-malate and activated by glucose 6-phosphate. A reaction scheme describing the interaction of enzyme, substrate and effectors is proposed. Values for the appropriate equilibrium constants have been calculated for the enzyme acting at pH 7.8, which is one of its two pH optima. The kinetics are more complicated at low pH, partly because of non-linear reaction rates and partly because inhibition by L-malate is not competitive. Activation by glucose 6-phosphate is similar at high and low pH values. The behaviour of a wide range of other possible effectors is described briefly.
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Charles A, Butler B, Willer D. Pyruvate carboxylase from the facultative chemolithotrophs Thiobacillus A2and Thiobacillus novellus. FEMS Microbiol Lett 1980. [DOI: 10.1111/j.1574-6968.1980.tb05020.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Moose PR. An investigation of gluconeogenesis in marine teleosts, and the effect of long-term exercise on hepatic gluconeogenesis. ACTA ACUST UNITED AC 1980. [DOI: 10.1016/0305-0491(80)90418-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Cannon B, Nedergaard J. The physiological role of pyruvate carboxylation in hamster brown adipose tissue. EUROPEAN JOURNAL OF BIOCHEMISTRY 1979; 94:419-26. [PMID: 428395 DOI: 10.1111/j.1432-1033.1979.tb12909.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
1. Pyruvate carboxylase is present in brown adipose tissue mitochondria. 2. In isolated mitochondria, pyruvate, bicarbonate and ATP, the substrates for pyruvate carboxylase, are able to replace added malate in supplying a condensing partner for acetyl-CoA formed from beta-oxidation of fatty acids. 3. In brown adipocytes, pyruvate and CO2 increase the rate of norepinephrine-stimulated respiration synergistically. 4. The norepinephrine-stimulated respiration in brown adipocytes is diminished when pyruvate transport into the mitochondria is inhibited. 5. Pyruvate carboxylation increases the intramitochondrial level of citric acid cycle intermediates, as shown by titrations of malonate inhibition of respiration. 6. Pyruvate carboxylation can continuously supply the mitochondria with citric acid cycle intermediates, as evidenced by its ability to maintain respiration when oxoglutarate conversion to glutamate is stimulated. 7. Pyruvate carboxylation is necessary for maximal oxygen consumption even when drainage of the citric acid cycle for amino acid synthesis is eliminated. 8. Pyruvate carboxylation explains observed effects of CO2 on respiration in brown adipocytes, and may also explain the increased glucose uptake by brown adipose tissue during thermogenesis in vivo.
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