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Chowdhury S, Hepper S, Lodi MK, Saier MH, Uetz P. The Protein Interactome of Glycolysis in Escherichia coli. Proteomes 2021; 9:proteomes9020016. [PMID: 33917325 PMCID: PMC8167557 DOI: 10.3390/proteomes9020016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 03/31/2021] [Accepted: 04/02/2021] [Indexed: 11/16/2022] Open
Abstract
Glycolysis is regulated by numerous mechanisms including allosteric regulation, post-translational modification or protein-protein interactions (PPI). While glycolytic enzymes have been found to interact with hundreds of proteins, the impact of only some of these PPIs on glycolysis is well understood. Here we investigate which of these interactions may affect glycolysis in E. coli and possibly across numerous other bacteria, based on the stoichiometry of interacting protein pairs (from proteomic studies) and their conservation across bacteria. We present a list of 339 protein-protein interactions involving glycolytic enzymes but predict that ~70% of glycolytic interactors are not present in adequate amounts to have a significant impact on glycolysis. Finally, we identify a conserved but uncharacterized subset of interactions that are likely to affect glycolysis and deserve further study.
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Affiliation(s)
- Shomeek Chowdhury
- Integrative Life Sciences, Virginia Commonwealth University, 1000 West Cary Street, Richmond, VA 23284, USA; or
| | - Stephen Hepper
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA 23284, USA; (S.H.); (M.K.L.)
| | - Mudassir K. Lodi
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA 23284, USA; (S.H.); (M.K.L.)
| | - Milton H. Saier
- Department of Molecular Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093, USA;
| | - Peter Uetz
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA 23284, USA; (S.H.); (M.K.L.)
- Correspondence:
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2
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Kitamura S, Shimizu H, Toya Y. Identification of a rate-limiting step in a metabolic pathway using the kinetic model and in vitro experiment. J Biosci Bioeng 2020; 131:271-276. [PMID: 33168471 DOI: 10.1016/j.jbiosc.2020.10.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/19/2020] [Accepted: 10/22/2020] [Indexed: 11/16/2022]
Abstract
Identification of the rate-limiting step in a metabolic pathway is an important challenge in metabolic engineering for enhancing pathway flow. Although specific enzyme activities (Vmax) provide valuable clues for the identification, it is time-consuming and difficult to measure multiple enzymes in the pathway because different assay protocols are required for each enzyme. In the present study, we propose a method to simultaneously determine the Vmax values of multiple enzymes using a kinetic model with a time course of the intermediate concentrations through an in vitro experiment. To demonstrate this method, nine glycolysis reactions for converting glucose-6-phosphate (G6P) to pyruvate in Escherichia coli were considered. In a reaction mixture containing G6P and cofactors, glycolysis was initiated by adding a crude cell extract obtained from stationary phase cells. The Vmax values were optimized to minimize the difference between the measured and simulated time-courses using a kinetic model. Metabolic control analysis using the kinetic model with the estimated Vmax values revealed that fructose bisphosphate aldolase (FBA) was the rate-limiting step in the upper part of glycolysis. The addition of FBA in the reaction mixture successfully increased the glycolytic flux in vitro. Furthermore, in vivo, the specific glucose consumption rate of an FBA overexpression strain was 1.4 times higher than that of the control strain during the stationary phase. These results confirmed that FBA was the rate-limiting step in glycolysis under the stationary phase. This approach provides Vmax values of multiple enzymes in a pathway for metabolic control analysis with a kinetic model.
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Affiliation(s)
- Sayaka Kitamura
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hiroshi Shimizu
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yoshihiro Toya
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan.
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3
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Ates-Alagoz Z, Kisla MM, Goker H, Yildiz S. Synthesis, Molecular Docking Studies and Antibacterial Activities of Novel Monocationic Indole-benzimidazole Derivatives. Med Chem 2020; 17:699-706. [PMID: 32310051 DOI: 10.2174/1573406416666200420080459] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 02/18/2020] [Accepted: 04/04/2020] [Indexed: 11/22/2022]
Abstract
BACKGROUND Finding efficient therapy against hospital-acquired MRSA infections has become rather important in the last decade. To this end, inhibition of the enzyme pyruvate kinase (PK) is being investigated for antibacterial activity, since this enzyme controls energy generation and metabolic flux distribution. Our main scaffold consists of benzimidazole and indole rings fused together. Both rings are famous for antibacterial properties and promising anti-MRSA compounds including indole ring. METHODS Several 1-substituted-2-(1H-indol-3-yl)-N-substituted-1H-benzimidazole-5-carboxamidine analogues were developed, synthesized and their antibacterial activities were evaluated against Staphylococcus aureus (ATCC 25923), Methicillin resistant Staphylococcus aureus (MRSA) (ATCC 43300), and Staphylococcus epidermidis (ATCC 12228) by using tube dilution method. Molecular docking analysis with a characteristic protein called MRSA- Pyruvate Kinase has been conducted for the assessment of the activities of our compounds against Methicillinresistant S. aureus (MRSA). RESULTS Among all the tested compounds, the most potent compound 36 had MIC values as 3.12, 3.12 and 6.25 μg/mL against S. aureus, Methicillin-resistant S. aureus (MRSA), and S. epidermidis, respectively. This compound had much better docking energy value than standard ampicillin and also created the link between two residues in different monomers of PK. DISCUSSION This approach of using indol-amidine conjugate systems as anti-MRSA agents may include MRSA-PK as potential target. To further increase the affinity, some other H-bonding parts may be added. By doing so, another bridge with Ile361 residues on both sides can be created. Our compounds tend to violate log P limit of Lipinski, therefore some optimizations with formulation can be made. CONCLUSION This study mainly includes the design, synthesis and optimization of indolebenzimidazole- amidine derivatives. Docking studies confirmed our results, since our most potent hit compound 36 created the necessary interactions between two chains of MRSA-PK. Further optimization can be considered to increase drug ability.
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Affiliation(s)
- Zeynep Ates-Alagoz
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Ankara University, Ankara, Turkey
| | - Mehmet Murat Kisla
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Ankara University, Ankara, Turkey
| | - Hakan Goker
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Ankara University, Ankara, Turkey
| | - Sulhiye Yildiz
- Department of Microbiology, Faculty of Pharmacy, Ankara University, Ankara, Turkey
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Han Q, Eiteman MA. Coupling xylitol dehydrogenase with NADH oxidase improves l-xylulose production in Escherichia coli culture. Enzyme Microb Technol 2017; 106:106-113. [PMID: 28859803 DOI: 10.1016/j.enzmictec.2017.07.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 07/06/2017] [Accepted: 07/21/2017] [Indexed: 11/30/2022]
Abstract
Escherichia coli expressing NAD-dependent xylitol-4-dehydrogenase (XDH) from Pantoea ananatis and growing on glucose or glycerol converts xylitol to the rare sugar l-xylulose. Although blocking potential l-xylulose consumption (l-xylulosekinase, lyxK) or co-expression of the glycerol facilitator (glpF) did not significantly affect l-xylulose formation, co-expressing XDH with water-forming NADH oxidase (NOX) from Streptococcus pneumoniae increased l-xylulose formation in shake flasks when glycerol was the carbon source. Controlled batch processes at the 1L scale demonstrated that the final equilibrium l-xylulose/xylitol ratio was correlated to the intracellular NAD+/NADH ratio, with 69% conversion of xylitol to l-xylulose and a yield of 0.88g l-xylulose/g xylitol consumed attained for MG1655/pZE12-xdh/pCS27-nox growing on glycerol. NADH oxidase was less effective at improving l-xylulose formation in the bioreactor than in shake flasks, likely as a result of an intrinsic maximum NAD+/NADH and l-xylulose/xylitol equilibrium ratio being attained. Intermittently feeding carbon source was ineffective at increasing the final l-xylulose concentration because introduction of carbon source was accompanied by a reduction in NAD+/NADH ratio. A batch process using 12g/L glycerol and 22g/L xylitol generated over 14g/L l-xylulose after 80h, corresponding to 65% conversion and a yield of 0.89g l-xylulose/g xylitol consumed.
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Affiliation(s)
- Qi Han
- School of Chemical, Materials and Biomedical Engineering University of Georgia, Athens, GA, 30602, USA
| | - Mark A Eiteman
- School of Chemical, Materials and Biomedical Engineering University of Georgia, Athens, GA, 30602, USA.
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Sánchez-Pascuala A, de Lorenzo V, Nikel PI. Refactoring the Embden-Meyerhof-Parnas Pathway as a Whole of Portable GlucoBricks for Implantation of Glycolytic Modules in Gram-Negative Bacteria. ACS Synth Biol 2017; 6:793-805. [PMID: 28121421 PMCID: PMC5440799 DOI: 10.1021/acssynbio.6b00230] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
![]()
The
Embden–Meyerhof–Parnas (EMP) pathway is generally
considered to be the biochemical standard for glucose catabolism.
Alas, its native genomic organization and the control of gene expression
in Escherichia coli are both very intricate, which
limits the portability of the EMP pathway to other biotechnologically
important bacterial hosts that lack the route. In this work, the genes
encoding all the enzymes of the linear EMP route have been individually
recruited from the genome of E. coli K-12, edited in silico to remove their endogenous regulatory signals,
and synthesized de novo following a standard (GlucoBrick)
that enables their grouping in the form of functional modules at the
user’s will. After verifying their activity in several glycolytic
mutants of E. coli, the versatility of these
GlucoBricks was demonstrated in quantitative physiology tests and
biochemical assays carried out in Pseudomonas putida KT2440 and P. aeruginosa PAO1 as the heterologous
hosts. Specific configurations of GlucoBricks were also adopted to
streamline the downward circulation of carbon from hexoses to pyruvate
in E. coli recombinants, thereby resulting in
a 3-fold increase of poly(3-hydroxybutyrate) synthesis from glucose.
Refactoring whole metabolic blocks in the fashion described in this
work thus eases the engineering of biochemical processes where the
optimization of carbon traffic is facilitated by the operation of
the EMP pathway—which yields more ATP than other glycolytic
routes such as the Entner–Doudoroff pathway.
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Affiliation(s)
- Alberto Sánchez-Pascuala
- Systems and Synthetic Biology
Program, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, 28049 Madrid, Spain
| | - Víctor de Lorenzo
- Systems and Synthetic Biology
Program, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, 28049 Madrid, Spain
| | - Pablo I. Nikel
- Systems and Synthetic Biology
Program, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, 28049 Madrid, Spain
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Rodriguez A, Martínez JA, Millard P, Gosset G, Portais JC, Létisse F, Bolivar F. Plasmid-encoded biosynthetic genes alleviate metabolic disadvantages while increasing glucose conversion to shikimate in an engineeredEscherichia colistrain. Biotechnol Bioeng 2017; 114:1319-1330. [DOI: 10.1002/bit.26264] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 01/17/2017] [Accepted: 02/08/2017] [Indexed: 12/31/2022]
Affiliation(s)
- Alberto Rodriguez
- Instituto de Biotecnología; Universidad Nacional Autónoma de México (UNAM); Cuernavaca Morelos Mexico
| | - Juan A. Martínez
- Instituto de Biotecnología; Universidad Nacional Autónoma de México (UNAM); Cuernavaca Morelos Mexico
| | - Pierre Millard
- LISBP, Université de Toulouse, CNRS, INRA; INSA; Toulouse France
| | - Guillermo Gosset
- Instituto de Biotecnología; Universidad Nacional Autónoma de México (UNAM); Cuernavaca Morelos Mexico
| | | | - Fabien Létisse
- LISBP, Université de Toulouse, CNRS, INRA; INSA; Toulouse France
| | - Francisco Bolivar
- Instituto de Biotecnología; Universidad Nacional Autónoma de México (UNAM); Cuernavaca Morelos Mexico
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7
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Zhai Z, An H, Wang G, Luo Y, Hao Y. Functional role of pyruvate kinase from Lactobacillus bulgaricus in acid tolerance and identification of its transcription factor by bacterial one-hybrid. Sci Rep 2015; 5:17024. [PMID: 26581248 PMCID: PMC4652205 DOI: 10.1038/srep17024] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 10/23/2015] [Indexed: 12/17/2022] Open
Abstract
Lactobacillus delbrueckii subsp. bulgaricus develops acid tolerance response when subjected to acid stress conditions, such as the induction of enzymes associated with carbohydrate metabolism. In this study, pyk gene encoding pyruvate kinase was over-expressed in heterologous host Lactococcus lactis NZ9000, and SDS-PAGE analysis revealed the successful expression of this gene in NZ9000. The survival rate of Pyk-overproducing strain was 45-fold higher than the control under acid stress condition (pH 4.0). In order to determine the transcription factor (TF) which regulates the expression of pyk by bacterial one-hybrid, we constructed a TF library including 65 TFs of L. bulgaricus. Western blotting indicated that TFs in this library could be successfully expressed in host strains. Subsequently, the promoter of pfk-pyk operon in L. bulgaricus was identified by 5′-RACE PCR. The bait plasmid pH3U3-p01 carrying the deletion fragment of pfk-pyk promoter captured catabolite control protein A (CcpA) which could regulate the expression of pyk by binding to a putative catabolite-responsive element (5′-TGTAAGCCCTAACA-3′) upstream the -35 region. Real-time qPCR analysis revealed the transcription of pyk was positively regulated by CcpA. This is the first report about identifying the TF of pyk in L. bulgaricus, which will provide new insight into the regulatory network.
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Affiliation(s)
- Zhengyuan Zhai
- Key Laboratory of Functional Dairy, Co-constructed by Ministry of Education and Beijing Municipality, College of Food Science &Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Haoran An
- Key Laboratory of Functional Dairy, Co-constructed by Ministry of Education and Beijing Municipality, College of Food Science &Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Guohong Wang
- Key Laboratory of Functional Dairy, Co-constructed by Ministry of Education and Beijing Municipality, College of Food Science &Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Yunbo Luo
- Key Laboratory of Functional Dairy, Co-constructed by Ministry of Education and Beijing Municipality, College of Food Science &Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Yanling Hao
- Key Laboratory of Functional Dairy, Co-constructed by Ministry of Education and Beijing Municipality, College of Food Science &Nutritional Engineering, China Agricultural University, Beijing 100083, China
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Jojima T, Noburyu R, Sasaki M, Tajima T, Suda M, Yukawa H, Inui M. Metabolic engineering for improved production of ethanol by Corynebacterium glutamicum. Appl Microbiol Biotechnol 2014; 99:1165-72. [DOI: 10.1007/s00253-014-6223-4] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 11/07/2014] [Accepted: 11/08/2014] [Indexed: 12/01/2022]
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9
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Chen JQ, Russo J. Dysregulation of glucose transport, glycolysis, TCA cycle and glutaminolysis by oncogenes and tumor suppressors in cancer cells. Biochim Biophys Acta Rev Cancer 2012; 1826:370-84. [PMID: 22750268 DOI: 10.1016/j.bbcan.2012.06.004] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Revised: 06/16/2012] [Accepted: 06/18/2012] [Indexed: 12/19/2022]
Abstract
A common set of functional characteristics of cancer cells is that cancer cells consume a large amount of glucose, maintain high rate of glycolysis and convert a majority of glucose into lactic acid even in the presence of oxygen compared to that of normal cells (Warburg's Effects). In addition, cancer cells exhibit substantial alterations in several energy metabolism pathways including glucose transport, tricarboxylic acid (TCA) cycle, glutaminolysis, mitochondrial respiratory chain oxidative phosphorylation and pentose phosphate pathway (PPP). In the present work, we focused on reviewing the current knowledge about the dysregulation of the proteins/enzymes involved in the key regulatory steps of glucose transport, glycolysis, TCA cycle and glutaminolysis by several oncogenes including c-Myc and hypoxia inducible factor-1 (HIF-1) and tumor suppressor, p53, in cancer cells. The dysregulation of glucose transport and energy metabolism pathways by oncogenes and lost functions of the tumor suppressors have been implicated as important biomarkers for cancer detection and as valuable targets for the development of new anticancer therapies.
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Affiliation(s)
- Jin-Qiang Chen
- Breast Cancer Research Laboratory, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
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10
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Šmerc A, Sodja E, Legiša M. Posttranslational modification of 6-phosphofructo-1-kinase as an important feature of cancer metabolism. PLoS One 2011; 6:e19645. [PMID: 21573193 PMCID: PMC3087806 DOI: 10.1371/journal.pone.0019645] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 04/12/2011] [Indexed: 01/12/2023] Open
Abstract
Background Human cancers consume larger amounts of glucose compared to normal tissues with most being converted and excreted as lactate despite abundant oxygen availability (Warburg effect). The underlying higher rate of glycolysis is therefore at the root of tumor formation and growth. Normal control of glycolytic allosteric enzymes appears impaired in tumors; however, the phenomenon has not been fully resolved. Methodology/Principal Findings In the present paper, we show evidence that the native 85-kDa 6-phosphofructo-1-kinase (PFK1), a key regulatory enzyme of glycolysis that is normally under the control of feedback inhibition, undergoes posttranslational modification. After proteolytic cleavage of the C-terminal portion of the enzyme, an active, shorter 47-kDa fragment was formed that was insensitive to citrate and ATP inhibition. In tumorigenic cell lines, only the short fragments but not the native 85-kDa PFK1 were detected by immunoblotting. Similar fragments were detected also in a tumor tissue that developed in mice after the subcutaneous infection with tumorigenic B16-F10 cells. Based on limited proteolytic digestion of the rabbit muscle PFK-M, an active citrate inhibition-resistant shorter form was obtained, indicating that a single posttranslational modification step was possible. The exact molecular masses of the active shorter PFK1 fragments were determined by inserting the truncated genes constructed from human muscle PFK1 cDNA into a pfk null E. coli strain. Two E. coli transformants encoding for the modified PFK1s of 45,551 Da and 47,835 Da grew in glucose medium. The insertion of modified truncated human pfkM genes also stimulated glucose consumption and lactate excretion in stable transfectants of non-tumorigenic human HEK cell, suggesting the important role of shorter PFK1 fragments in enhancing glycolytic flux. Conclusions/Significance Posttranslational modification of PFK1 enzyme might be the pivotal factor of deregulated glycolytic flux in tumors that in combination with altered signaling mechanisms essentially supports fast proliferation of cancer cells.
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Affiliation(s)
- Andreja Šmerc
- Department of Biotechnology, National Institute of Chemistry, Ljubljana, Slovenia
| | - Eva Sodja
- Department of Biotechnology, National Institute of Chemistry, Ljubljana, Slovenia
| | - Matic Legiša
- Department of Biotechnology, National Institute of Chemistry, Ljubljana, Slovenia
- * E-mail:
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Wang S, Spor A, Nidelet T, Montalent P, Dillmann C, de Vienne D, Sicard D. Switch between life history strategies due to changes in glycolytic enzyme gene dosage in Saccharomyces cerevisiae. Appl Environ Microbiol 2011; 77:452-9. [PMID: 21075872 PMCID: PMC3020566 DOI: 10.1128/aem.00808-10] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Accepted: 10/26/2010] [Indexed: 12/24/2022] Open
Abstract
Adaptation is the process whereby a population or species becomes better fitted to its habitat through modifications of various life history traits which can be positively or negatively correlated. The molecular factors underlying these covariations remain to be elucidated. Using Saccharomyces cerevisiae as a model system, we have investigated the effects on life history traits of varying the dosage of genes involved in the transformation of resources into energy. Changing gene dosage for each of three glycolytic enzyme genes (hexokinase 2, phosphoglucose isomerase, and fructose-1,6-bisphosphate aldolase) resulted in variation in enzyme activities, glucose consumption rate, and life history traits (growth rate, carrying capacity, and cell size). However, the range of effects depended on which enzyme was expressed differently. Most interestingly, these changes revealed a genetic trade-off between carrying capacity and cell size, supporting the discovery of two extreme life history strategies already described in yeast populations: the "ants," which have lower glycolytic gene dosage, take up glucose slowly, and have a small cell size but reach a high carrying capacity, and the "grasshoppers," which have higher glycolytic gene dosage, consume glucose more rapidly, and allocate it to a larger cell size but reach a lower carrying capacity. These results demonstrate antagonist pleiotropy for glycolytic genes and show that altered dosage of a single gene drives a switch between two life history strategies in yeast.
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Affiliation(s)
- Shaoxiao Wang
- CNRS, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France, Université Paris-Sud, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France, INRA, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France
| | - Aymé Spor
- CNRS, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France, Université Paris-Sud, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France, INRA, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France
| | - Thibault Nidelet
- CNRS, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France, Université Paris-Sud, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France, INRA, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France
| | - Pierre Montalent
- CNRS, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France, Université Paris-Sud, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France, INRA, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France
| | - Christine Dillmann
- CNRS, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France, Université Paris-Sud, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France, INRA, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France
| | - Dominique de Vienne
- CNRS, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France, Université Paris-Sud, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France, INRA, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France
| | - Delphine Sicard
- CNRS, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France, Université Paris-Sud, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France, INRA, UMR 0320/UMR 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France
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Abstract
Whole-cell biocatalysis utilizes native or recombinant enzymes produced by cellular metabolism to perform synthetically interesting reactions. Besides hydrolases, oxidoreductases represent the most applied enzyme class in industry. Oxidoreductases are attributed a high future potential, especially for applications in the chemical and pharmaceutical industries, as they enable highly interesting chemistry (e.g., the selective oxyfunctionalization of unactivated C-H bonds). Redox reactions are characterized by electron transfer steps that often depend on redox cofactors as additional substrates. Their regeneration typically is accomplished via the metabolism of whole-cell catalysts. Traditionally, studies towards productive redox biocatalysis focused on the biocatalytic enzyme, its activity, selectivity, and specificity, and several successful examples of such processes are running commercially. However, redox cofactor regeneration by host metabolism was hardly considered for the optimization of biocatalytic rate, yield, and/or titer. This article reviews molecular mechanisms of oxidoreductases with synthetic potential and the host redox metabolism that fuels biocatalytic reactions with redox equivalents. The tools discussed in this review for investigating redox metabolism provide the basis for studies aiming at a deeper understanding of the interplay between synthetically active enzymes and metabolic networks. The ultimate goal of rational whole-cell biocatalyst engineering and use for fine chemical production is discussed.
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Tevž G, Benčina M, Legiša M. Enhancing itaconic acid production by Aspergillus terreus. Appl Microbiol Biotechnol 2010; 87:1657-64. [DOI: 10.1007/s00253-010-2642-z] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Revised: 04/19/2010] [Accepted: 04/19/2010] [Indexed: 11/28/2022]
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14
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Shiloach J, Reshamwala S, Noronha SB, Negrete A. Analyzing metabolic variations in different bacterial strains, historical perspectives and current trends – example E. coli. Curr Opin Biotechnol 2010; 21:21-6. [DOI: 10.1016/j.copbio.2010.01.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2009] [Accepted: 01/06/2010] [Indexed: 10/19/2022]
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15
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Buch AD, Archana G, Kumar GN. Enhanced citric acid biosynthesis in Pseudomonas fluorescens ATCC 13525 by overexpression of the Escherichia coli citrate synthase gene. MICROBIOLOGY-SGM 2009; 155:2620-2629. [PMID: 19443543 DOI: 10.1099/mic.0.028878-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Citric acid secretion by fluorescent pseudomonads has a distinct significance in microbial phosphate solubilization. The role of citrate synthase in citric acid biosynthesis and glucose catabolism in pseudomonads was investigated by overexpressing the Escherichia coli citrate synthase (gltA) gene in Pseudomonas fluorescens ATCC 13525. The resultant approximately 2-fold increase in citrate synthase activity in the gltA-overexpressing strain Pf(pAB7) enhanced the intracellular and extracellular citric acid yields during the stationary phase, by about 2- and 26-fold, respectively, as compared to the control, without affecting the growth rate, glucose depletion rate or biomass yield. Decreased glucose consumption was paralleled by increased gluconic acid production due to an increase in glucose dehydrogenase activity. While the extracellular acetic acid yield increased in Pf(pAB7), pyruvic acid secretion decreased, correlating with an increase in pyruvate carboxylase activity and suggesting an increased demand for the anabolic precursor oxaloacetate. Activities of two other key enzymes, glucose-6-phosphate dehydrogenase and isocitrate dehydrogenase, remained unaltered, and the contribution of phosphoenolpyruvate carboxylase and isocitrate lyase to glucose catabolism was negligible. Strain Pf(pAB7) demonstrated an enhanced phosphate-solubilizing ability compared to the control. Co-expression of the Synechococcus elongatus PCC 6301 phosphoenolpyruvate carboxylase and E. coli gltA genes in P. fluorescens ATCC 13525, so as to supplement oxaloacetate for citrate biosynthesis, neither significantly affected citrate biosynthesis nor caused any change in the other physiological and biochemical parameters measured, despite approximately 1.3- and 5-fold increases in citrate synthase and phosphoenolpyruvate carboxylase activities, respectively. Thus, our results demonstrate that citrate synthase is rate-limiting in enhancing citrate biosynthesis in P. fluorescens ATCC 13525. Significantly low extracellular citrate levels as compared to the intracellular levels in Pf(pAB7) suggested a probable limitation of efficient citrate transport.
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Affiliation(s)
- Aditi D Buch
- Molecular Microbial Biochemistry Laboratory, Department of Biochemistry, Faculty of Science, M. S. University of Baroda, Vadodara 390 002, India
| | - G Archana
- Department of Microbiology and Biotechnology Center, Faculty of Science, M. S. University of Baroda, Vadodara 390 002, India
| | - G Naresh Kumar
- Molecular Microbial Biochemistry Laboratory, Department of Biochemistry, Faculty of Science, M. S. University of Baroda, Vadodara 390 002, India
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Metabolic control analysis: a tool for designing strategies to manipulate metabolic pathways. J Biomed Biotechnol 2008; 2008:597913. [PMID: 18629230 PMCID: PMC2447884 DOI: 10.1155/2008/597913] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Revised: 01/16/2008] [Accepted: 03/26/2008] [Indexed: 02/06/2023] Open
Abstract
The traditional experimental approaches used for changing the flux or the concentration of a particular metabolite of a metabolic pathway have been mostly based on the inhibition or over-expression of the presumed rate-limiting step. However, the attempts to manipulate a metabolic pathway by following such approach have proved to be unsuccessful. Metabolic Control Analysis (MCA) establishes how to determine, quantitatively, the degree of control that a given enzyme exerts on flux and on the concentration of metabolites, thus substituting the intuitive, qualitative concept of rate limiting step. Moreover, MCA helps to understand (i) the underlying mechanisms by which a given enzyme exerts high or low control and (ii) why the control of the pathway is shared by several pathway enzymes and transporters. By applying MCA it is possible to identify the steps that should be modified to achieve a successful alteration of flux or metabolite concentration in pathways of biotechnological (e.g., large scale metabolite production) or clinical relevance (e.g., drug therapy). The different MCA experimental approaches developed for the determination of the flux-control distribution in several pathways are described. Full understanding of the pathway properties when is working under a variety of conditions can help to attain a successful manipulation of flux and metabolite concentration.
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Huerta-Beristain G, Utrilla J, Hernández-Chávez G, Bolívar F, Gosset G, Martinez A. Specific ethanol production rate in ethanologenic Escherichia coli strain KO11 Is limited by pyruvate decarboxylase. J Mol Microbiol Biotechnol 2008; 15:55-64. [PMID: 18349551 DOI: 10.1159/000111993] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Modification of ethanol productivity and yield, using mineral medium supplemented with glucose or xylose as carbon sources, was studied in ethanologenic Escherichia coli KO11 by increasing the activity of five key carbon metabolism enzymes. KO11 efficiently converted glucose or xylose to ethanol with a yield close to 100% of the theoretical maximum when growing in rich medium. However, when KO11 ferments glucose or xylose in mineral medium, the ethanol yields decreased to only 70 and 60%, respectively. An increase in GALP(Ec) (permease of galactose-glucose-xylose) or PGK(Ec) (phosphoglycerate kinase) activities did not change xylose or glucose and ethanol flux. However, when PDC(Zm) (pyruvate decarboxylase from Zymomonas mobilis) activity was increased 7-fold, the yields of ethanol from glucose or xylose were increased to 85 and 75%, respectively, and organic acid formation rates were reduced. Furthermore, as a response to a reduction in acetate and ATP yield, and a limited PDC(Zm) activity, an increase in PFK(Ec) (phosphofructokinase) or PYK(Bs) (pyruvate kinase from Bacillus stearothermophilus) activity drastically reduced glucose or xylose consumption and ethanol formation flux. This experimental metabolic control analysis showed that ethanol flux in KO11 is negatively controlled by phosphofructokinase and pyruvate kinase, and positively influenced by the PDC(Zm) activity level.
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Affiliation(s)
- Gerardo Huerta-Beristain
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, México
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18
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Martínez K, de Anda R, Hernández G, Escalante A, Gosset G, Ramírez OT, Bolívar FG. Coutilization of glucose and glycerol enhances the production of aromatic compounds in an Escherichia coli strain lacking the phosphoenolpyruvate: carbohydrate phosphotransferase system. Microb Cell Fact 2008; 7:1. [PMID: 18211716 PMCID: PMC2249568 DOI: 10.1186/1475-2859-7-1] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Accepted: 01/22/2008] [Indexed: 11/14/2022] Open
Abstract
Background Escherichia coli strains lacking the phosphoenolpyruvate: carbohydrate phosphotransferase system (PTS) are capable of coutilizing glucose and other carbon sources due to the absence of catabolite repression by glucose. In these strains, the lack of this important regulatory and transport system allows the coexistence of glycolytic and gluconeogenic pathways. Strains lacking PTS have been constructed with the goal of canalizing part of the phosphoenolpyruvate (PEP) not consumed in glucose transport to the aromatic pathway. The deletion of the ptsHIcrr operon inactivates PTS causing poor growth on this sugar; nonetheless, fast growing mutants on glucose have been isolated (PB12 strain). However, there are no reported studies concerning the growth potential of a PTS- strain in mixtures of different carbon sources to enhance the production of aromatics compounds. Results PB12 strain is capable of coutilizing mixtures of glucose-arabinose, glucose-gluconate and glucose-glycerol. This capacity increases its specific growth rate (μ) given that this strain metabolizes more moles of carbon source per unit time. The presence of plasmids pRW300aroGfbr and pCLtktA reduces the μ of strain PB12 in all mixtures of carbon sources, but enhances the productivity and yield of aromatic compounds, especially in the glucose-glycerol mixture, as compared to glucose or glycerol cultures. No acetate was detected in the glycerol and the glucose-glycerol batch fermentations. Conclusion Due to the lack of catabolite repression, PB12 strain carrying multicopy plasmids containing tktA and aroGfbr genes is capable of coutilizing glucose and other carbon sources; this capacity, reduces its μ but increases the production of aromatic compounds.
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Affiliation(s)
- Karla Martínez
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Av, Universidad 2001 CP 62210, Cuernavaca, Morelos, México.
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De Mey M, De Maeseneire S, Soetaert W, Vandamme E. Minimizing acetate formation in E. coli fermentations. J Ind Microbiol Biotechnol 2007; 34:689-700. [PMID: 17668256 DOI: 10.1007/s10295-007-0244-2] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2006] [Accepted: 07/08/2007] [Indexed: 10/23/2022]
Abstract
Escherichia coli remains the best-established production organism in industrial biotechnology. However, when aerobic fermentation runs at high growth rates, considerable amounts of acetate are accumulated as by-product. This by-product has negative effects on growth and protein production. Over the last 20 years, substantial research efforts have been expended on reducing acetate accumulation during aerobic growth of E. coli on glucose. From the onset it was clear that this quest would not be a simple or uncomplicated one. Simple deletion of the acetate pathway reduced the acetate accumulation, but other by-products were formed. This mini review gives a clear outline of these research efforts and their outcome, including bioprocess level approaches and genetic approaches. Recently, the latter seems to have some promising results.
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Affiliation(s)
- Marjan De Mey
- Laboratory of Industrial Microbiology and Biocatalysis, Department of Biochemical and Microbial Technology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium.
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20
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Sakai T, Nakamura N, Umitsuki G, Nagai K, Wachi M. Increased production of pyruvic acid by Escherichia coli RNase G mutants in combination with cra mutations. Appl Microbiol Biotechnol 2007; 76:183-92. [PMID: 17483940 DOI: 10.1007/s00253-007-1006-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2007] [Revised: 04/13/2007] [Accepted: 04/15/2007] [Indexed: 12/01/2022]
Abstract
The Escherichia coli RNase G is known as an endoribonuclease responsible for the 5'-end maturation of 16S rRNA and degradation of several specific mRNAs such as adhE and eno mRNAs. In this study, we found that an RNase G mutant derived from the MC1061 strain did not grow on a glucose minimal medium. Genetic analysis revealed that simultaneous defects of cra and ilvIH, encoding a transcriptional regulator of glycolysis/gluconeogenesis and one of isozymes of acetohydroxy acid synthase, respectively, were required for this phenomenon to occur. The results of additional experiments presented here indicate that the RNase G mutation, in combination with cra mutation, caused the increased production of pyruvic acid from glucose, which was then preferentially converted to valine due to the ilvIH mutation, resulting in depletion of isoleucine. In fact, the rng cra double mutant produced increased amount of pyruvate in the medium. These results suggest that the RNase G mutation could be applied in the breeding of producer strains of pyruvate and its derivatives such as valine.
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Affiliation(s)
- Taro Sakai
- Department of Bioengineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8503, Japan
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21
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Hiller J, Franco-Lara E, Weuster-Botz D. Metabolic profiling of Escherichia coli cultivations: evaluation of extraction and metabolite analysis procedures. Biotechnol Lett 2007; 29:1169-78. [PMID: 17479221 DOI: 10.1007/s10529-007-9384-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Revised: 03/21/2007] [Accepted: 03/26/2007] [Indexed: 11/30/2022]
Abstract
The quantitative estimation of intracellular metabolite concentrations (metabolic profiling) is a prerequisite for a better understanding of biological processes and thus inevitable for the rational improvement of microbial production strains and process design. Since pool sizes of substrates regulate flux through different enzymes, the accurate determination of intracellular metabolite concentrations is necessary to understand in vivo reaction kinetics. Quantification of intracellular concentrations of glycolytic intermediates in Escherichia coli K12 was achieved by using a novel in situ rapid sampling and quenching procedure. A new extraction procedure using buffered hot water was established. By use of simultaneous multi-substrate feeding with various ratios of glucose, fructose and acetate during continuous cultivations several metabolic states were induced. Metabolic flux analysis and the newly developed metabolic profiling procedure were used to determine in vivo enzyme kinetics as exemplified for fructose 1,6-bisphosphate aldolase and citrate synthase.
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Affiliation(s)
- Julia Hiller
- Lehrstuhl für Bioverfahrenstechnik, Technische Universität München, Boltzmannstr. 15, 85748, Garching, Germany.
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22
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Nöh K, Grönke K, Luo B, Takors R, Oldiges M, Wiechert W. Metabolic flux analysis at ultra short time scale: Isotopically non-stationary 13C labeling experiments. J Biotechnol 2007; 129:249-67. [PMID: 17207877 DOI: 10.1016/j.jbiotec.2006.11.015] [Citation(s) in RCA: 170] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2006] [Revised: 10/12/2006] [Accepted: 11/16/2006] [Indexed: 11/16/2022]
Abstract
A novel approach to (13)C metabolic flux analysis (MFA) is presented using cytosolic metabolite pool sizes and their (13)C labeling data from an isotopically non-stationary (13)C labeling experiment (INST-CLE). The procedure is demonstrated with an E. coli wild type strain grown at fed batch conditions. The intra cellular labeling dynamics are excited by a sudden step increase of the (13)C portion in the substrate feed. Due to unchanged saturation of the substrate uptake system, the metabolic fluxes remain constant during the following sampling time period of only 16s, in which 20 samples are taken by an automated rapid sampling device immediately stopping metabolism by methanol quenching. Subsequent cell disruptive sample preparation and LC-MS/MS enabled simultaneous determination of pool sizes and mass isotopomers of intra cellular metabolites requiring detection limits in the nM range. Based on this data the new computational flux analysis tool 13CFLUX/INST is used to determine the intra cellular fluxes based on a complex carbon labeling network model. The measured data is in good agreement with the model predictions, thus proving the applicability of the new isotopically non-stationary (13)C metabolic flux analysis (INST-(13)C-MFA) concept. Moreover, it is shown that significant new information with respect to flux identifiability, non-measurable pool sizes, data consistency, or large storage pools can be taken from the novel kind of experimental data. This offers new insight into the biological operation of the metabolic network in vivo.
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Affiliation(s)
- Katharina Nöh
- Institute of Biotechnology, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany.
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23
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E. coli metabolomics: capturing the complexity of a “simple” model. TOPICS IN CURRENT GENETICS 2007. [DOI: 10.1007/4735_2007_0221] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Kümmel A, Panke S, Heinemann M. Putative regulatory sites unraveled by network-embedded thermodynamic analysis of metabolome data. Mol Syst Biol 2006; 2:2006.0034. [PMID: 16788595 PMCID: PMC1681506 DOI: 10.1038/msb4100074] [Citation(s) in RCA: 199] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Accepted: 05/07/2006] [Indexed: 11/09/2022] Open
Abstract
As one of the most recent members of the omics family, large-scale quantitative metabolomics data are currently complementing our systems biology data pool and offer the chance to integrate the metabolite level into the functional analysis of cellular networks. Network-embedded thermodynamic analysis (NET analysis) is presented as a framework for mechanistic and model-based analysis of these data. By coupling the data to an operating metabolic network via the second law of thermodynamics and the metabolites' Gibbs energies of formation, NET analysis allows inferring functional principles from quantitative metabolite data; for example it identifies reactions that are subject to active allosteric or genetic regulation as exemplified with quantitative metabolite data from Escherichia coli and Saccharomyces cerevisiae. Moreover, the optimization framework of NET analysis was demonstrated to be a valuable tool to systematically investigate data sets for consistency, for the extension of sub-omic metabolome data sets and for resolving intracompartmental concentrations from cell-averaged metabolome data. Without requiring any kind of kinetic modeling, NET analysis represents a perfectly scalable and unbiased approach to uncover insights from quantitative metabolome data.
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Affiliation(s)
- Anne Kümmel
- Bioprocess Laboratory, Institute of Process Engineering, ETH Zurich, Zurich, Switzerland
- Present address: Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland
| | - Sven Panke
- Bioprocess Laboratory, Institute of Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Matthias Heinemann
- Bioprocess Laboratory, Institute of Process Engineering, ETH Zurich, Zurich, Switzerland
- Present address: Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland
- Institute of Molecular Systems Biology, ETH Zurich, Wolfgang-Pauli-Strasse 16, 8093 Zurich, Switzerland. Tel.: +41 44 632 63 66; Fax: +41 44 633 10 51; E-mail:
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Abstract
Central metabolism of carbohydrates uses the Embden-Meyerhof-Parnas (EMP), pentose phosphate (PP), and Entner-Doudoroff (ED) pathways. This review reviews the biological roles of the enzymes and genes of these three pathways of E. coli. Glucose, pentoses, and gluconate are primarily discussed as the initial substrates of the three pathways, respectively. The genetic and allosteric regulatory mechanisms of glycolysis and the factors that affect metabolic flux through the pathways are considered here. Despite the fact that a lot of information on each of the reaction steps has been accumulated over the years for E. coli, surprisingly little quantitative information has been integrated to analyze glycolysis as a system. Therefore, the review presents a detailed description of each of the catalytic steps by a systemic approach. It considers both structural and kinetic aspects. Models that include kinetic information of the reaction steps will always contain the reaction stoichiometry and therefore follow the structural constraints, but in addition to these also kinetic rate laws must be fulfilled. The kinetic information obtained on isolated enzymes can be integrated using computer models to simulate behavior of the reaction network formed by these enzymes. Successful examples of such approaches are the modeling of glycolysis in S. cerevisiae, the parasite Trypanosoma brucei, and the red blood cell. With the rapid developments in the field of Systems Biology many new methods have been and will be developed, for experimental and theoretical approaches, and the authors expect that these will be applied to E. coli glycolysis in the near future.
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Affiliation(s)
- Tony Romeo
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Jacky L Snoep
- Department of Biochemistry, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa, and Department of Molecular Cell Physiology, Vrije Universiteit, Amsterdam, The Netherlands
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26
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Shimazu M, Vetcher L, Galazzo JL, Licari P, Santi DV. A sensitive and robust method for quantification of intracellular short-chain coenzyme A esters. Anal Biochem 2004; 328:51-9. [PMID: 15081907 DOI: 10.1016/j.ab.2004.01.025] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2003] [Indexed: 11/23/2022]
Abstract
A procedure for the analysis of short-chain intracellular coenzyme A (CoA) esters and adenine nucleotide pools in microbial cells is described. The simultaneous isolation of bacterial cells from media, quenching of their metabolism, and extraction of metabolites was accomplished by centrifugation of cells through a layer of silicone oil into a denser solution of trichloroacetic acid. The acid was neutralized by extraction into Freon containing tri-n-octylamine to provide a salt-free solution of cell metabolites. After high-performance liquid chromatography separation, CoA, CoA esters, and adenine-containing nucleotides were derivatized by postcolumn reaction with bromoacetaldehyde to form the fluorescent 1,N6-ethenoadenine adducts which were analyzed by a fluorescence detector at picomolar levels.
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Affiliation(s)
- Mark Shimazu
- Kosan Biosciences, Inc., 3832 Bay Center Place, Hayward, CA 94545, USA
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Ramos A, Neves AR, Ventura R, Maycock C, López P, Santos H. Effect of pyruvate kinase overproduction on glucose metabolism of Lactococcus lactis. MICROBIOLOGY-SGM 2004; 150:1103-1111. [PMID: 15073320 DOI: 10.1099/mic.0.26695-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Lactococcus lactis strain NZ9000(pNZpyk), which overproduces pyruvate kinase (PK), was constructed. The pNZpyk plasmid carries the P(nisA)-pyk transcriptional fusion, and the overexpression of its pyk gene was accomplished by using the nisin-inducible expression system of the NZ9000 strain. In vivo (13)C- and (31)P-NMR spectroscopy was used to evaluate the effect of this modification on the metabolism of glucose in non-growing cells. A detailed description of the kinetics of glucose, end products, glycolytic intermediates, NAD(+) and NADH was obtained. A 15-fold increase in the level of PK did not increase the overall glycolytic flux, which, on the contrary, was slightly reduced. Significant differences were observed in (i) the level of 3-phosphoglycerate (3-PGA) and phosphoenolpyruvate (PEP), metabolites associated with starvation; (ii) the rate of fructose 1,6-bisphosphate (FBP) depletion upon glucose exhaustion; and (iii) the NAD(+)/NADH ratio during glucose catabolism. In the mutant, the rate of FBP consumption after glucose depletion was notably accelerated under anaerobic conditions, whereas 3-PGA and PEP decreased to undetectable levels. Furthermore, the level of NAD(+) decreased steadily during the utilization of glucose, probably due to the unanticipated reduction in the lactate dehydrogenase activity in comparison with the control strain, NZ9000(pNZ8020). The results show that PK is an important bottleneck to carbon flux only when glucose becomes limiting; in the overproducer this constriction was no longer present, as evidenced by the faster FBP consumption and lack of accumulation of 3-PGA and PEP in anaerobic as well as aerobic conditions. Despite these clear changes, the PK-overproducing strain showed typical homolactic metabolism under anaerobic conditions, as did the strain harbouring the vector plasmid without the pyk insert. However, under an oxygen atmosphere, there was increased channelling of carbon to the production of acetate and acetoin, to the detriment of lactate production.
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Affiliation(s)
- Ana Ramos
- Instituto de Tecnologia Química e Biológica/Universidade Nova de Lisboa and Instituto de Biologia Experimental e Tecnológica, Rua da Quinta Grande, 6, Apt 127, 2780-156 Oeiras, Portugal
| | - Ana Rute Neves
- Instituto de Tecnologia Química e Biológica/Universidade Nova de Lisboa and Instituto de Biologia Experimental e Tecnológica, Rua da Quinta Grande, 6, Apt 127, 2780-156 Oeiras, Portugal
| | - Rita Ventura
- Instituto de Tecnologia Química e Biológica/Universidade Nova de Lisboa and Instituto de Biologia Experimental e Tecnológica, Rua da Quinta Grande, 6, Apt 127, 2780-156 Oeiras, Portugal
| | - Christopher Maycock
- Instituto de Tecnologia Química e Biológica/Universidade Nova de Lisboa and Instituto de Biologia Experimental e Tecnológica, Rua da Quinta Grande, 6, Apt 127, 2780-156 Oeiras, Portugal
| | - Paloma López
- Centro de Investigaciones Biológicas, Velazquez 144, Madrid, Spain
| | - Helena Santos
- Instituto de Tecnologia Química e Biológica/Universidade Nova de Lisboa and Instituto de Biologia Experimental e Tecnológica, Rua da Quinta Grande, 6, Apt 127, 2780-156 Oeiras, Portugal
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Sauer U, Canonaco F, Heri S, Perrenoud A, Fischer E. The soluble and membrane-bound transhydrogenases UdhA and PntAB have divergent functions in NADPH metabolism of Escherichia coli. J Biol Chem 2003; 279:6613-9. [PMID: 14660605 DOI: 10.1074/jbc.m311657200] [Citation(s) in RCA: 410] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pentose phosphate pathway and isocitrate dehydrogenase are generally considered to be the major sources of the anabolic reductant NADPH. As one of very few microbes, Escherichia coli contains two transhydrogenase isoforms with unknown physiological function that could potentially transfer electrons directly from NADH to NADP+ and vice versa. Using defined mutants and metabolic flux analysis, we identified the proton-translocating transhydrogenase PntAB as a major source of NADPH in E. coli. During standard aerobic batch growth on glucose, 35-45% of the NADPH that is required for biosynthesis was produced via PntAB, whereas pentose phosphate pathway and isocitrate dehydrogenase contributed 35-45% and 20-25%, respectively. The energy-independent transhydrogenase UdhA, in contrast, was essential for growth under metabolic conditions with excess NADPH formation, i.e. growth on acetate or in a phosphoglucose isomerase mutant that catabolized glucose through the pentose phosphate pathway. Thus, both isoforms have divergent physiological functions: energy-dependent reduction of NADP+ with NADH by PntAB and reoxidation of NADPH by UdhA. Expression appeared to be modulated by the redox state of cellular metabolism, because genetic and environmental manipulations that increased or decreased NADPH formation down-regulated pntA or udhA transcription, respectively. The two transhydrogenase isoforms provide E. coli primary metabolism with an extraordinary flexibility to cope with varying catabolic and anabolic demands, which raises two general questions: why do only a few bacteria contain both isoforms, and how do other organisms manage NADPH metabolism?
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Affiliation(s)
- Uwe Sauer
- Institute of Biotechnology, ETH Zürich, CH-8093 Zürich, Switzerland.
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29
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Roberts DP, Lohrke SM. United States Department of Agriculture-Agricultural Research Service research programs in biological control of plant diseases. PEST MANAGEMENT SCIENCE 2003; 59:654-664. [PMID: 12846315 DOI: 10.1002/ps.613] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A number of USDA-ARS programs directed at overcoming impediments to the use of biocontrol agents on a commercial scale are described. These include improvements in screening techniques, taxonomic studies to identify beneficial strains more precisely, and studies on various aspects of the large-scale production of biocontrol agents. Another broad area of studies covers the ecological aspects of biocontrol agents-their interaction with the pathogen, with the plant and with other aspects of the environmental complex. Examples of these studies are given and their relevance to the further development and expansion of biocontrol agents is discussed.
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Affiliation(s)
- Daniel P Roberts
- Sustainable Agricultural Systems Laboratory, USDA-ARS, Beltsville, MD 20705-2350, USA.
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30
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Muñoz ME, Ponce E. Pyruvate kinase: current status of regulatory and functional properties. Comp Biochem Physiol B Biochem Mol Biol 2003; 135:197-218. [PMID: 12798932 DOI: 10.1016/s1096-4959(03)00081-2] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Pyruvate kinase (PK) is a key enzyme for the glycolytic pathway and carbon metabolism in general. On the basis of the relevance and enormous diverse properties of this enzyme, this paper describes the results of a current and extensive review that determines the sites of conservation and/or difference in PK sequences, and the differences in the functional and regulatory properties of the enzymes. An alignment and analysis of 50 PK sequences from different sources and a phylogenetic tree are presented. This analysis was performed with reference to crystallographically characterized PK principally from E. coli, cat and rabbit muscle. A number of attributes of the enzyme that make it of particular interest in biomedicine and industry are also discussed.
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Affiliation(s)
- Ma Enriqueta Muñoz
- Facultad de Ciencias Quíicas e Ingenierí, Universidad Autónoma de Baja California, Av. Tecnológico s/n, Mesa de Otay, B.C., Tijuana, Mexico C.P. 22390
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Lohrke SM, Dery PD, Li W, Reedy R, Kobayashi DY, Roberts DR. Mutation of rpiA in Enterobacter cloacae decreases seed and root colonization and biocontrol of damping-off caused by Pythium ultimum on cucumber. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2002; 15:817-825. [PMID: 12182339 DOI: 10.1094/mpmi.2002.15.8.817] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Strains of Enterobacter cloacae show promise as biocontrol agents for Pythium ultimum-induced damping-off on cucumber and other crops. E. cloacae A145 is a mini-Tn5 Km transposon mutant of strain 501R3 that was significantly reduced in suppression of damping-off on cucumber caused by P. ultimum. Strain A145 was deficient in colonization of cucumber, sunflower, and wheat seeds and significantly reduced in colonization of corn and cowpea seeds relative to strain 501R3. Populations of strain A145 were also significantly lower than those of strain 501R3 at all sampling times in cucumber, wheat, and sunflower rhizosphere. Populations of strain A145 were not detectable in any rhizosphere after 42 days, while populations of strain 501R3 remained at substantial levels throughout all experiments. Molecular characterization of strain A145 indicated mini-Tn5 Km was inserted in a region of the E. cloacae genome with a high degree of DNA and amino acid sequence similarity to rpiA, which encodes ribose-5-phosphate isomerase. In Escherichia coli, RpiA catalyzes the interconversion of ribose-5-phosphate and ribulose-5-phosphate and is a key enzyme in the pentose phosphate pathway. Ribose-5-phosphate isomerase activity in cell lysates from strain A145 was approximately 3.5% of that from strain 501R3. In addition, strain A145 was a ribose auxotroph, as expected for an rpiA mutant. Introduction of a 1.0-kb DNA fragment containing only the rpiA homologue into strain A145 restored ribose phosphate isomerase activity, prototrophy, seedling colonization, and disease suppression to levels similar to those associated with strain 501R3. Experiments reported here indicate a key role for rpiA and possibly the pentose phosphate pathway in suppression of damping-off and colonization of subterranean portions of plants by E. cloacae.
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Affiliation(s)
- Scott M Lohrke
- Sustainable Agricultural Systems Laboratory, USDA-ARS, Beltsville, MD 20705, USA
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Sauer U. Evolutionary engineering of industrially important microbial phenotypes. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2002; 73:129-69. [PMID: 11816810 DOI: 10.1007/3-540-45300-8_7] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The tremendous complexity of dynamic interactions in cellular systems often impedes practical applications of metabolic engineering that are largely based on available molecular or functional knowledge. In contrast, evolutionary engineering follows nature's 'engineering' principle by variation and selection. Thus, it is a complementary strategy that offers compelling scientific and applied advantages for strain development and process optimization, provided a desired phenotype is amenable to direct or indirect selection. In addition to simple empirical strain development by random mutation and direct selection on plates, evolutionary engineering also encompasses recombination and continuous evolution of large populations over many generations. Two distinct evolutionary engineering applications are likely to gain more relevance in the future: first, as an integral component in metabolic engineering of strains with improved phenotypes, and second, to elucidate the molecular basis of desired phenotypes for subsequent transfer to other hosts. The latter will profit from the broader availability of recently developed methodologies for global response analysis at the genetic and metabolic level. These methodologies facilitate identification of the molecular basis of evolved phenotypes. It is anticipated that, together with novel analytical techniques, bioinformatics, and computer modeling of cellular functions and activities, evolutionary engineering is likely to find its place in the metabolic engineer's toolbox for research and strain development. This review presents evolutionary engineering of whole cells as an emerging methodology that draws on the latest advances from a wide range of scientific and technical disciplines.
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Affiliation(s)
- U Sauer
- Institute of Biotechnology, ETH Zürich, 8093 Zürich, Switzerland.
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Emmerling M, Dauner M, Ponti A, Fiaux J, Hochuli M, Szyperski T, Wüthrich K, Bailey JE, Sauer U. Metabolic flux responses to pyruvate kinase knockout in Escherichia coli. J Bacteriol 2002; 184:152-64. [PMID: 11741855 PMCID: PMC134756 DOI: 10.1128/jb.184.1.152-164.2002] [Citation(s) in RCA: 198] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The intracellular carbon flux distribution in wild-type and pyruvate kinase-deficient Escherichia coli was estimated using biosynthetically directed fractional 13C labeling experiments with [U-13C6]glucose in glucose- or ammonia-limited chemostats, two-dimensional nuclear magnetic resonance (NMR) spectroscopy of cellular amino acids, and a comprehensive isotopomer model. The general response to disruption of both pyruvate kinase isoenzymes in E. coli was a local flux rerouting via the combined reactions of phosphoenolpyruvate (PEP) carboxylase and malic enzyme. Responses in the pentose phosphate pathway and the tricarboxylic acid cycle were strongly dependent on the environmental conditions. In addition, high futile cycling activity via the gluconeogenic PEP carboxykinase was identified at a low dilution rate in glucose-limited chemostat culture of pyruvate kinase-deficient E. coli, with a turnover that is comparable to the specific glucose uptake rate. Furthermore, flux analysis in mutant cultures indicates that glucose uptake in E. coli is not catalyzed exclusively by the phosphotransferase system in glucose-limited cultures at a low dilution rate. Reliability of the flux estimates thus obtained was verified by statistical error analysis and by comparison to intracellular carbon flux ratios that were independently calculated from the same NMR data by metabolic flux ratio analysis.
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Affiliation(s)
- Marcel Emmerling
- Institute of Biotechnology, ETH Zürich, CH-8093 Zürich, Switzerland
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Frey AD, Fiaux J, Szyperski T, Wüthrich K, Bailey JE, Kallio PT. Dissection of central carbon metabolism of hemoglobin-expressing Escherichia coli by 13C nuclear magnetic resonance flux distribution analysis in microaerobic bioprocesses. Appl Environ Microbiol 2001; 67:680-7. [PMID: 11157231 PMCID: PMC92635 DOI: 10.1128/aem.67.2.680-687.2001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2000] [Accepted: 11/29/2000] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli MG1655 cells expressing Vitreoscilla hemoglobin (VHb), Alcaligenes eutrophus flavohemoprotein (FHP), the N-terminal hemoglobin domain of FHP (FHPg), and a fusion protein which comprises VHb and the A. eutrophus C-terminal reductase domain (VHb-Red) were grown in a microaerobic bioreactor to study the effects of low oxygen concentrations on the central carbon metabolism, using fractional (13)C-labeling of the proteinogenic amino acids and two-dimensional [(13)C, (1)H]-correlation nuclear magnetic resonance (NMR) spectroscopy. The NMR data revealed differences in the intracellular carbon fluxes between E. coli cells expressing either VHb or VHb-Red and cells expressing A. eutrophus FHP or the truncated heme domain (FHPg). E. coli MG1655 cells expressing either VHb or VHb-Red were found to function with a branched tricarboxylic acid (TCA) cycle. Furthermore, cellular demands for ATP and reduction equivalents in VHb- and VHb-Red-expressing cells were met by an increased flux through glycolysis. In contrast, in E. coli cells expressing A. eutrophus hemeproteins, the TCA cycle is running cyclically, indicating a shift towards a more aerobic regulation. Consistently, E. coli cells displaying FHP and FHPg activity showed lower production of the typical anaerobic by-products formate, acetate, and D-lactate. The implications of these observations for biotechnological applications are discussed.
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Affiliation(s)
- A D Frey
- Institute of Biotechnology, ETH Zürich, CH-8093 Zürich, Switzerland
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Abstract
Complete genomes, far advanced proteomes, and even 'metabolomes' are available for at least a few organisms, e.g., Escherichia coli. Systematic functional analyses of such complete data sets will produce a wealth of information and promise an understanding of the dynamics of complex biological networks and perhaps even of entire living organisms. Such complete and holistic descriptions of biological systems, however, will increasingly require a quantitative analysis and the help of mathematical models for simulating whole systems. In particular, new procedures are required that allow a meaningful reduction of the information derived from complex systems that will consequently be used in the modeling process. In this review the biological elements of such a modeling procedure will be described. In a first step, complex living systems must be structured into well-defined and clearly delimited functional units, the elements of which have a common physiological goal, belong to a single genetic unit, and respond to the signals of a signal transduction system that senses changes in physiological states of the organism. These functional units occur at each level of complexity and more complex units originate by grouping several lower level elements into a single, more complex unit. To each complexity level corresponds a global regulator that is epistatic over lower level regulators. After its structuring into modules (functional units), a biological system is converted in a second step into mathematical submodels that by progressive combination can also be assembled into more aggregated model structures. Such a simplification of a cell (an organism) reduces its complexity to a level amenable to present modeling capacities. The universal biochemistry, however, promises a set of rules valid for modeling biological systems, from unicellular microorganisms and cells, to multicellular organisms and to populations.
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Affiliation(s)
- J W Lengeler
- Fachbereich Biologie/Chemie, Arbeitsgruppe Genetik, Universität Osnabrück, Germany
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Emmerling M, Bailey JE, Sauer U. Altered regulation of pyruvate kinase or co-overexpression of phosphofructokinase increases glycolytic fluxes in resting Escherichia coli. Biotechnol Bioeng 2000; 67:623-7. [PMID: 10649237 DOI: 10.1002/(sici)1097-0290(20000305)67:5<623::aid-bit13>3.0.co;2-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Glycolytic fluxes in resting Escherichia coli were enhanced by overexpression of heterologous pyruvate kinases (Pyk) from Bacillus stearothermophilus and Zymomonas mobilis, but not homologous Pyk. Compared to the control, an increase of 10% in specific glucose consumption and of 15% in specific ethanol production rates was found in anaerobic resting cells, expressing the heterologous Pyks, that were harvested from exponentially growing aerobic cultures. A further increase in glycolytic flux was achieved by simultaneous overexpression of E. coli phosphofructokinase (Pfk) and Pyk with specific glucose consumption and ethanol production rates of 25% and 35% greater, respectively, than the control. Fluxes to lactate were not significantly affected, contrary to previous observations with resting cells harvested from anaerobically growing cultures. To correlate the physiology of resting cells with the physiology of cells prior to harvest, we determined the relevant growth parameters from aerobic and anaerobic precultures. We conclude that glycolytic fluxes in E. coli with submaximal (aerobic) metabolic activity can be increased by overexpression of pyruvate kinases which do not require allosteric activation or co-overexpression with Pfk. However, such improvements require more extensive engineering in E. coli with near maximal (anaerobic) metabolic activity.
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Affiliation(s)
- M Emmerling
- Institute of Biotechnology, ETH Zürich, CH-8093 Zürich, Switzerland
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Sauer U, Lasko DR, Fiaux J, Hochuli M, Glaser R, Szyperski T, Wüthrich K, Bailey JE. Metabolic flux ratio analysis of genetic and environmental modulations of Escherichia coli central carbon metabolism. J Bacteriol 1999; 181:6679-88. [PMID: 10542169 PMCID: PMC94132 DOI: 10.1128/jb.181.21.6679-6688.1999] [Citation(s) in RCA: 262] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The response of Escherichia coli central carbon metabolism to genetic and environmental manipulation has been studied by use of a recently developed methodology for metabolic flux ratio (METAFoR) analysis; this methodology can also directly reveal active metabolic pathways. Generation of fluxome data arrays by use of the METAFoR approach is based on two-dimensional (13)C-(1)H correlation nuclear magnetic resonance spectroscopy with fractionally labeled biomass and, in contrast to metabolic flux analysis, does not require measurements of extracellular substrate and metabolite concentrations. METAFoR analyses of E. coli strains that moderately overexpress phosphofructokinase, pyruvate kinase, pyruvate decarboxylase, or alcohol dehydrogenase revealed that only a few flux ratios change in concert with the overexpression of these enzymes. Disruption of both pyruvate kinase isoenzymes resulted in altered flux ratios for reactions connecting the phosphoenolpyruvate (PEP) and pyruvate pools but did not significantly alter central metabolism. These data indicate remarkable robustness and rigidity in central carbon metabolism in the presence of genetic variation. More significant physiological changes and flux ratio differences were seen in response to altered environmental conditions. For example, in ammonia-limited chemostat cultures, compared to glucose-limited chemostat cultures, a reduced fraction of PEP molecules was derived through at least one transketolase reaction, and there was a higher relative contribution of anaplerotic PEP carboxylation than of the tricarboxylic acid (TCA) cycle for oxaloacetate synthesis. These two parameters also showed significant variation between aerobic and anaerobic batch cultures. Finally, two reactions catalyzed by PEP carboxykinase and malic enzyme were identified by METAFoR analysis; these had previously been considered absent in E. coli cells grown in glucose-containing media. Backward flux from the TCA cycle to glycolysis, as indicated by significant activity of PEP carboxykinase, was found only in glucose-limited chemostat culture, demonstrating that control of this futile cycle activity is relaxed under severe glucose limitation.
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Affiliation(s)
- U Sauer
- Institut für Biotechnologie, ETH Zürich, CH-8093 Zürich, Switzerland.
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