1
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Huang Y, Mukherjee A, Schink S, Benites NC, Basan M. Evolution and stability of complex microbial communities driven by trade-offs. Mol Syst Biol 2024; 20:997-1005. [PMID: 38961275 PMCID: PMC11369148 DOI: 10.1038/s44320-024-00051-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Revised: 06/18/2024] [Accepted: 06/20/2024] [Indexed: 07/05/2024] Open
Abstract
Microbial communities are ubiquitous in nature and play an important role in ecology and human health. Cross-feeding is thought to be core to microbial communities, though it remains unclear precisely why it emerges. Why have multi-species microbial communities evolved in many contexts and what protects microbial consortia from invasion? Here, we review recent insights into the emergence and stability of coexistence in microbial communities. A particular focus is the long-term evolutionary stability of coexistence, as observed for microbial communities that spontaneously evolved in the E. coli long-term evolution experiment (LTEE). We analyze these findings in the context of recent work on trade-offs between competing microbial objectives, which can constitute a mechanistic basis for the emergence of coexistence. Coexisting communities, rather than monocultures of the 'fittest' single strain, can form stable endpoints of evolutionary trajectories. Hence, the emergence of coexistence might be an obligatory outcome in the evolution of microbial communities. This implies that rather than embodying fragile metastable configurations, some microbial communities can constitute formidable ecosystems that are difficult to disrupt.
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Affiliation(s)
- Yanqing Huang
- Harvard Medical School, Department of Systems Biology, Boston, USA
| | - Avik Mukherjee
- Harvard Medical School, Department of Systems Biology, Boston, USA
| | - Severin Schink
- Harvard Medical School, Department of Systems Biology, Boston, USA
| | | | - Markus Basan
- Harvard Medical School, Department of Systems Biology, Boston, USA.
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2
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Kong Y, Chen H, Huang X, Chang L, Yang B, Chen W. Precise metabolic modeling in post-omics era: accomplishments and perspectives. Crit Rev Biotechnol 2024:1-19. [PMID: 39198033 DOI: 10.1080/07388551.2024.2390089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 07/18/2024] [Accepted: 07/23/2024] [Indexed: 09/01/2024]
Abstract
Microbes have been extensively utilized for their sustainable and scalable properties in synthesizing desired bio-products. However, insufficient knowledge about intracellular metabolism has impeded further microbial applications. The genome-scale metabolic models (GEMs) play a pivotal role in facilitating a global understanding of cellular metabolic mechanisms. These models enable rational modification by exploring metabolic pathways and predicting potential targets in microorganisms, enabling precise cell regulation without experimental costs. Nonetheless, simplified GEM only considers genome information and network stoichiometry while neglecting other important bio-information, such as enzyme functions, thermodynamic properties, and kinetic parameters. Consequently, uncertainties persist particularly when predicting microbial behaviors in complex and fluctuant systems. The advent of the omics era with its massive quantification of genes, proteins, and metabolites under various conditions has led to the flourishing of multi-constrained models and updated algorithms with improved predicting power and broadened dimension. Meanwhile, machine learning (ML) has demonstrated exceptional analytical and predictive capacities when applied to training sets of biological big data. Incorporating the discriminant strength of ML with GEM facilitates mechanistic modeling efficiency and improves predictive accuracy. This paper provides an overview of research innovations in the GEM, including multi-constrained modeling, analytical approaches, and the latest applications of ML, which may contribute comprehensive knowledge toward genetic refinement, strain development, and yield enhancement for a broad range of biomolecules.
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Affiliation(s)
- Yawen Kong
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, P. R. China
- School of Food Science and Technology, Jiangnan University, Wuxi, P. R. China
| | - Haiqin Chen
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, P. R. China
- School of Food Science and Technology, Jiangnan University, Wuxi, P. R. China
| | - Xinlei Huang
- The Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Wuxi, P. R. China
| | - Lulu Chang
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, P. R. China
- School of Food Science and Technology, Jiangnan University, Wuxi, P. R. China
| | - Bo Yang
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, P. R. China
- School of Food Science and Technology, Jiangnan University, Wuxi, P. R. China
| | - Wei Chen
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, P. R. China
- School of Food Science and Technology, Jiangnan University, Wuxi, P. R. China
- National Engineering Research Center for Functional Food, Jiangnan University, Wuxi, P. R. China
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3
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Carlson RP, Beck AE, Benitez MG, Harcombe WR, Mahadevan R, Gedeon T. Cell Geometry and Membrane Protein Crowding Constrain Growth Rate, Overflow Metabolism, Respiration, and Maintenance Energy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.21.609071. [PMID: 39229203 PMCID: PMC11370460 DOI: 10.1101/2024.08.21.609071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 09/05/2024]
Abstract
A metabolic theory is presented for predicting maximum growth rate, overflow metabolism, respiration efficiency, and maintenance energy flux based on the intersection of cell geometry, membrane protein crowding, and metabolism. The importance of cytosolic macromolecular crowding on phenotype has been established in the literature but the importance of surface area has been largely overlooked due to incomplete knowledge of membrane properties. We demonstrate that the capacity of the membrane to host proteins increases with growth rate offsetting decreases in surface area-to-volume ratios (SA:V). This increase in membrane protein is hypothesized to be essential to competitive Escherichia coli phenotypes. The presented membrane-centric theory uses biophysical properties and metabolic systems analysis to successfully predict the phenotypes of E. coli K-12 strains, MG1655 and NCM3722, which are genetically similar but have SA:V ratios that differ up to 30%, maximum growth rates on glucose media that differ by 40%, and overflow phenotypes that start at growth rates that differ by 80%. These analyses did not consider cytosolic macromolecular crowding, highlighting the distinct properties of the presented theory. Cell geometry and membrane protein crowding are significant biophysical constraints on phenotype and provide a theoretical framework for improved understanding and control of cell biology.
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Affiliation(s)
- Ross P Carlson
- Department of Chemical and Biological Engineering, Center for Biofilm Engineering, Montana State University, Bozeman, MT USA
| | - Ashley E Beck
- Department of Biological and Environmental Sciences, Carroll College, Helena, MT USA
| | | | - William R Harcombe
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN USA
| | | | - Tomáš Gedeon
- Department of Mathematical Sciences, Montana State University, Bozeman, MT USA
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4
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Radde N, Mortensen GA, Bhat D, Shah S, Clements JJ, Leonard SP, McGuffie MJ, Mishler DM, Barrick JE. Measuring the burden of hundreds of BioBricks defines an evolutionary limit on constructability in synthetic biology. Nat Commun 2024; 15:6242. [PMID: 39048554 PMCID: PMC11269670 DOI: 10.1038/s41467-024-50639-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Accepted: 07/18/2024] [Indexed: 07/27/2024] Open
Abstract
Engineered DNA will slow the growth of a host cell if it redirects limiting resources or otherwise interferes with homeostasis. Escape mutants that alleviate this burden can rapidly evolve and take over cell populations, making genetic engineering less reliable and predictable. Synthetic biologists often use genetic parts encoded on plasmids, but their burden is rarely characterized. We measured how 301 BioBrick plasmids affected Escherichia coli growth and found that 59 (19.6%) were burdensome, primarily because they depleted the limited gene expression resources of host cells. Overall, no BioBricks reduced the growth rate of E. coli by >45%, which agreed with a population genetic model that predicts such plasmids should be unclonable. We made this model available online for education ( https://barricklab.org/burden-model ) and added our burden measurements to the iGEM Registry. Our results establish a fundamental limit on what DNA constructs and genetic modifications can be successfully engineered into cells.
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Affiliation(s)
- Noor Radde
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX, USA
| | - Genevieve A Mortensen
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX, USA
| | - Diya Bhat
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX, USA
| | - Shireen Shah
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX, USA
| | - Joseph J Clements
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX, USA
| | - Sean P Leonard
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX, USA
| | - Matthew J McGuffie
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX, USA
| | - Dennis M Mishler
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX, USA
- The Freshman Research Initiative, College of Natural Sciences, The University of Texas at Austin, Austin, TX, USA
| | - Jeffrey E Barrick
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX, USA.
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5
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Labourel FJF, Daubin V, Menu F, Rajon E. Proteome allocation and the evolution of metabolic cross-feeding. Evolution 2024; 78:849-859. [PMID: 38376478 DOI: 10.1093/evolut/qpae008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 01/12/2024] [Accepted: 01/18/2024] [Indexed: 02/21/2024]
Abstract
In a common instance of metabolic cross-feeding (MCF), an organism incompletely metabolizes nutrients and releases metabolites that are used by another to produce energy or building blocks. Why would the former waste edible food, and why does this preferentially occur at specific locations in a metabolic pathway have challenged evolutionary theory for decades. To address these questions, we combine adaptive dynamics with an explicit model of cell metabolism, including enzyme-driven catalysis of metabolic reactions and the cellular constraints acting on the proteome that may incur a cost to expressing all enzymes along a pathway. After pointing out that cells should in principle prioritize upstream reactions when metabolites are restrained inside the cell, we show that the occurrence of permeability-driven MCF is rare and requires that an intermediate metabolite be extremely diffusive. Indeed, only at very high levels of membrane permeability (consistent with those of acetate and glycerol, for instance) and under distinctive sets of parameters should the population diversify and MCF evolve. These results help understand the origins of simple microbial communities, such as those that readily evolve in short-term evolutionary experiments, and may later be extended to investigate how evolution has progressively built up today's extremely diverse ecosystems.
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Affiliation(s)
- Florian J F Labourel
- Univ Lyon, Universite Lyon 1, CNRS, Laboratoire de Biometrie et Biologie Evolutive UMR5558, Villeurbanne, France
- Milner Centre for Evolution, University of Bath, Bath, United Kingdom
- Department of Life Sciences, University of Bath, Bath, United Kingdom
| | - Vincent Daubin
- Univ Lyon, Universite Lyon 1, CNRS, Laboratoire de Biometrie et Biologie Evolutive UMR5558, Villeurbanne, France
| | - Frédéric Menu
- Univ Lyon, Universite Lyon 1, CNRS, Laboratoire de Biometrie et Biologie Evolutive UMR5558, Villeurbanne, France
| | - Etienne Rajon
- Univ Lyon, Universite Lyon 1, CNRS, Laboratoire de Biometrie et Biologie Evolutive UMR5558, Villeurbanne, France
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6
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Gecse G, Labunskaite R, Pedersen M, Kilstrup M, Johanson T. Minimizing acetate formation from overflow metabolism in Escherichia coli: comparison of genetic engineering strategies to improve robustness toward sugar gradients in large-scale fermentation processes. Front Bioeng Biotechnol 2024; 12:1339054. [PMID: 38419731 PMCID: PMC10899681 DOI: 10.3389/fbioe.2024.1339054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 01/15/2024] [Indexed: 03/02/2024] Open
Abstract
Introduction: Escherichia coli, a well characterized workhorse in biotechnology, has been used to produce many recombinant proteins and metabolites, but have a major drawback in its tendency to revert to overflow metabolism. This phenomenon occurs when excess sugar triggers the production of mainly acetate under aerobic conditions, a detrimental by-product that reduces carbon efficiency, increases cell maintenance, and ultimately inhibits growth. Although this can be prevented by controlled feeding of the sugar carbon source to limit its availability, gradients in commercial-scale bioreactors can still induce it in otherwise carbon-limited cells. While the underlying mechanisms have been extensively studied, these have mostly used non-limited cultures. In contrast, industrial production typically employs carbon-limited processes, which results in a substantially different cell physiology. Objective: The objective of this study was to evaluate and compare the efficiency of different metabolic engineering strategies with the aim to reduce overflow metabolism and increase the robustness of an industrial 2'-O-fucosyllactose producing strain under industrially relevant conditions. Methods: Three distinct metabolic engineering strategies were compared: i) alterations to pathways leading to and from acetate, ii) increased flux towards the tricarboxylic acid (TCA) cycle, and iii) reduced glucose uptake rate. The engineered strains were evaluated for growth, acetate formation, and product yield under non-limiting batch conditions, carbon limited fed-batch conditions, and after a glucose pulse in fed-batch mode. Results and Discussion: The findings demonstrated that blockage of the major acetate production pathways by deletion of the pta and poxB genes or increased carbon flux into the TCA cycle by overexpression of the gltA and deletion of the iclR genes, were efficient ways to reduce acetate accumulation. Surprisingly, a reduced glucose uptake rate did not reduce acetate formation despite it having previously been shown as a very effective strategy. Interestingly, overexpression of gltA was the most efficient way to reduce acetate accumulation in non-limited cultures, whereas disruption of the poxB and pta genes was more effective for carbon-limited cultures exposed to a sudden glucose shock. Strains from both strategies showed increased tolerance towards a glucose pulse during carbon-limited growth indicating feasible ways to engineer industrial E. coli strains with enhanced robustness.
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Affiliation(s)
| | | | | | - Mogens Kilstrup
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
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7
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Yazdanpanah S, Motamedian E, Shojaosadati SA. Integrating gene expression data into a genome-scale metabolic model to identify reprogramming during adaptive evolution. PLoS One 2023; 18:e0292433. [PMID: 37788289 PMCID: PMC10547208 DOI: 10.1371/journal.pone.0292433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 09/19/2023] [Indexed: 10/05/2023] Open
Abstract
The development of a method for identifying latent reprogramming in gene expression data resulting from adaptive laboratory evolution (ALE) in response to genetic or environmental perturbations has been a challenge. In this study, a method called Metabolic Reprogramming Identifier (MRI), based on the integration of expression data to a genome-scale metabolic model has been developed. To identify key genes playing the main role in reprogramming, a MILP problem is presented and maximization of an adaptation score as a criterion indicating a pattern of using metabolism with maximum utilization of gene expression resources is defined as an objective function. Then, genes with complete expression usage and significant expression differences between wild-type and evolved strains were selected as key genes for reprogramming. This score is also applied to evaluate the compatibility of expression patterns with maximal use of key genes. The method was implemented to investigate the reprogramming of Escherichia coli during adaptive evolution caused by changing carbon sources. cyoC and cydB responsible for establishing proton gradient across the inner membrane were identified to be vital in the E. coli reprogramming when switching from glucose to lactate. These results indicate the importance of the inner membrane in reprogramming of E. coli to adapt to the new environment. The method predicts no reprogramming occurs during the evolution for growth on glycerol.
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Affiliation(s)
- Shaghayegh Yazdanpanah
- Faculty of Chemical Engineering, Department of Biotechnology, Tarbiat Modares University, Tehran, Iran
| | - Ehsan Motamedian
- Faculty of Chemical Engineering, Department of Biotechnology, Tarbiat Modares University, Tehran, Iran
| | - Seyed Abbas Shojaosadati
- Faculty of Chemical Engineering, Department of Biotechnology, Tarbiat Modares University, Tehran, Iran
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8
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Abner K, Šverns P, Arold J, Morell I, Lints T, Medri S, Seiman A, Adamberg K, Vilu R. Self-reproduction and doubling time limits of different cellular subsystems. NPJ Syst Biol Appl 2023; 9:44. [PMID: 37730753 PMCID: PMC10511633 DOI: 10.1038/s41540-023-00306-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 08/29/2023] [Indexed: 09/22/2023] Open
Abstract
Ribosomes which can self-replicate themselves practically autonomously in beneficial physicochemical conditions have been recognized as the central organelles of cellular self-reproduction processes. The challenge of cell design is to understand and describe the rates and mechanisms of self-reproduction processes of cells as of coordinated functioning of ribosomes and the enzymatic networks of different functional complexity that support those ribosomes. We show that doubling times of proto-cells (ranging from simplest replicators up to those reaching the size of E. coli) increase rather with the number of different cell component species than with the total numbers of cell components. However, certain differences were observed between cell components in increasing the doubling times depending on the types of relationships between those cell components and ribosomes. Theoretical limits of doubling times of the self-reproducing proto-cells determined by the molecular parameters of cell components and cell processes were in the range between 6-40 min.
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Affiliation(s)
- Kristo Abner
- Center of Food and Fermentation Technologies, Mäealuse 2/4, 12618, Tallinn, Estonia
- Department of Chemistry and Biotechnology, School of Science, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
| | - Peter Šverns
- Center of Food and Fermentation Technologies, Mäealuse 2/4, 12618, Tallinn, Estonia
- Department of Chemistry and Biotechnology, School of Science, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
| | - Janar Arold
- Center of Food and Fermentation Technologies, Mäealuse 2/4, 12618, Tallinn, Estonia
- Department of Chemistry and Biotechnology, School of Science, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
| | - Indrek Morell
- Center of Food and Fermentation Technologies, Mäealuse 2/4, 12618, Tallinn, Estonia
- Department of Chemistry and Biotechnology, School of Science, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
| | - Taivo Lints
- Center of Food and Fermentation Technologies, Mäealuse 2/4, 12618, Tallinn, Estonia
- Department of Chemistry and Biotechnology, School of Science, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
| | - Sander Medri
- Center of Food and Fermentation Technologies, Mäealuse 2/4, 12618, Tallinn, Estonia
- Department of Chemistry and Biotechnology, School of Science, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
| | - Andrus Seiman
- Center of Food and Fermentation Technologies, Mäealuse 2/4, 12618, Tallinn, Estonia
- Department of Chemistry and Biotechnology, School of Science, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
| | - Kaarel Adamberg
- Center of Food and Fermentation Technologies, Mäealuse 2/4, 12618, Tallinn, Estonia
- Department of Chemistry and Biotechnology, School of Science, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
| | - Raivo Vilu
- Center of Food and Fermentation Technologies, Mäealuse 2/4, 12618, Tallinn, Estonia.
- Department of Chemistry and Biotechnology, School of Science, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia.
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9
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Taha A, Patón M, Penas DR, Banga JR, Rodríguez J. Optimal evaluation of energy yield and driving force in microbial metabolic pathway variants. PLoS Comput Biol 2023; 19:e1011264. [PMID: 37410779 DOI: 10.1371/journal.pcbi.1011264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 06/12/2023] [Indexed: 07/08/2023] Open
Abstract
This work presents a methodology to evaluate the bioenergetic feasibility of alternative metabolic pathways for a given microbial conversion, optimising their energy yield and driving forces as a function of the concentration of metabolic intermediates. The tool, based on thermodynamic principles and multi-objective optimisation, accounts for pathway variants in terms of different electron carriers, as well as energy conservation (proton translocating) reactions within the pathway. The method also accommodates other constraints, some of them non-linear, such as the balance of conserved moieties. The approach involves the transformation of the maximum energy yield problem into a multi-objective mixed-integer linear optimisation problem which is then subsequently solved using the epsilon-constraint method, highlighting the trade-off between yield and rate in metabolic reactions. The methodology is applied to analyse several pathway alternatives occurring during propionate oxidation in anaerobic fermentation processes, as well as to the reverse TCA cycle pathway occurring during autotrophic microbial CO2 fixation. The results obtained using the developed methodology match previously reported literature and bring about insights into the studied pathways.
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Affiliation(s)
- Ahmed Taha
- Department of Chemical Engineering, Research and Innovation Center on CO2 and H2 (RICH) Khalifa University, Abu Dhabi, United Arab Emirates
| | - Mauricio Patón
- Department of Chemical Engineering, Research and Innovation Center on CO2 and H2 (RICH) Khalifa University, Abu Dhabi, United Arab Emirates
| | - David R Penas
- Computational Biology Lab, MBG-CSIC (Spanish National Research Council), Pontevedra, Galicia, Spain
| | - Julio R Banga
- Computational Biology Lab, MBG-CSIC (Spanish National Research Council), Pontevedra, Galicia, Spain
| | - Jorge Rodríguez
- Department of Chemical Engineering, Research and Innovation Center on CO2 and H2 (RICH) Khalifa University, Abu Dhabi, United Arab Emirates
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10
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Strain B, Morrissey J, Antonakoudis A, Kontoravdi C. Genome-scale models as a vehicle for knowledge transfer from microbial to mammalian cell systems. Comput Struct Biotechnol J 2023; 21:1543-1549. [PMID: 36879884 PMCID: PMC9984296 DOI: 10.1016/j.csbj.2023.02.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 02/06/2023] [Accepted: 02/06/2023] [Indexed: 02/10/2023] Open
Abstract
With the plethora of omics data becoming available for mammalian cell and, increasingly, human cell systems, Genome-scale metabolic models (GEMs) have emerged as a useful tool for their organisation and analysis. The systems biology community has developed an array of tools for the solution, interrogation and customisation of GEMs as well as algorithms that enable the design of cells with desired phenotypes based on the multi-omics information contained in these models. However, these tools have largely found application in microbial cells systems, which benefit from smaller model size and ease of experimentation. Herein, we discuss the major outstanding challenges in the use of GEMs as a vehicle for accurately analysing data for mammalian cell systems and transferring methodologies that would enable their use to design strains and processes. We provide insights on the opportunities and limitations of applying GEMs to human cell systems for advancing our understanding of health and disease. We further propose their integration with data-driven tools and their enrichment with cellular functions beyond metabolism, which would, in theory, more accurately describe how resources are allocated intracellularly.
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Affiliation(s)
- Benjamin Strain
- Department of Chemical Engineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - James Morrissey
- Department of Chemical Engineering, Imperial College London, London SW7 2AZ, United Kingdom
| | | | - Cleo Kontoravdi
- Department of Chemical Engineering, Imperial College London, London SW7 2AZ, United Kingdom
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11
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El-Mansi M. Control of central metabolism’s architecture in Escherichia coli: An overview. Microbiol Res 2023; 266:127224. [DOI: 10.1016/j.micres.2022.127224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 10/05/2022] [Accepted: 10/05/2022] [Indexed: 11/06/2022]
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12
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Metabolomics and modelling approaches for systems metabolic engineering. Metab Eng Commun 2022; 15:e00209. [PMID: 36281261 PMCID: PMC9587336 DOI: 10.1016/j.mec.2022.e00209] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 10/13/2022] [Accepted: 10/14/2022] [Indexed: 11/21/2022] Open
Abstract
Metabolic engineering involves the manipulation of microbes to produce desirable compounds through genetic engineering or synthetic biology approaches. Metabolomics involves the quantitation of intracellular and extracellular metabolites, where mass spectrometry and nuclear magnetic resonance based analytical instrumentation are often used. Here, the experimental designs, sample preparations, metabolite quenching and extraction are essential to the quantitative metabolomics workflow. The resultant metabolomics data can then be used with computational modelling approaches, such as kinetic and constraint-based modelling, to better understand underlying mechanisms and bottlenecks in the synthesis of desired compounds, thereby accelerating research through systems metabolic engineering. Constraint-based models, such as genome scale models, have been used successfully to enhance the yield of desired compounds from engineered microbes, however, unlike kinetic or dynamic models, constraint-based models do not incorporate regulatory effects. Nevertheless, the lack of time-series metabolomic data generation has hindered the usefulness of dynamic models till today. In this review, we show that improvements in automation, dynamic real-time analysis and high throughput workflows can drive the generation of more quality data for dynamic models through time-series metabolomics data generation. Spatial metabolomics also has the potential to be used as a complementary approach to conventional metabolomics, as it provides information on the localization of metabolites. However, more effort must be undertaken to identify metabolites from spatial metabolomics data derived through imaging mass spectrometry, where machine learning approaches could prove useful. On the other hand, single-cell metabolomics has also seen rapid growth, where understanding cell-cell heterogeneity can provide more insights into efficient metabolic engineering of microbes. Moving forward, with potential improvements in automation, dynamic real-time analysis, high throughput workflows, and spatial metabolomics, more data can be produced and studied using machine learning algorithms, in conjunction with dynamic models, to generate qualitative and quantitative predictions to advance metabolic engineering efforts.
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13
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Cadart C, Heald R. Scaling of biosynthesis and metabolism with cell size. Mol Biol Cell 2022; 33:pe5. [PMID: 35862496 PMCID: PMC9582640 DOI: 10.1091/mbc.e21-12-0627] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 05/24/2022] [Accepted: 05/25/2022] [Indexed: 11/17/2022] Open
Abstract
Cells adopt a size that is optimal for their function, and pushing them beyond this limit can cause cell aging and death by senescence or reduce proliferative potential. However, by increasing their genome copy number (ploidy), cells can increase their size dramatically and homeostatically maintain physiological properties such as biosynthesis rate. Recent studies investigating the relationship between cell size and rates of biosynthesis and metabolism under normal, polyploid, and pathological conditions are revealing new insights into how cells attain the best function or fitness for their size by tuning processes including transcription, translation, and mitochondrial respiration. A new frontier is to connect single-cell scaling relationships with tissue and whole-organism physiology, which promises to reveal molecular and evolutionary principles underlying the astonishing diversity of size observed across the tree of life.
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Affiliation(s)
- Clotilde Cadart
- Molecular and Cell Biology Department, University of California, Berkeley, Berkeley, CA 94720-3200
| | - Rebecca Heald
- Molecular and Cell Biology Department, University of California, Berkeley, Berkeley, CA 94720-3200
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14
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Domenzain I, Sánchez B, Anton M, Kerkhoven EJ, Millán-Oropeza A, Henry C, Siewers V, Morrissey JP, Sonnenschein N, Nielsen J. Reconstruction of a catalogue of genome-scale metabolic models with enzymatic constraints using GECKO 2.0. Nat Commun 2022; 13:3766. [PMID: 35773252 PMCID: PMC9246944 DOI: 10.1038/s41467-022-31421-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 06/16/2022] [Indexed: 01/08/2023] Open
Abstract
Genome-scale metabolic models (GEMs) have been widely used for quantitative exploration of the relation between genotype and phenotype. Streamlined integration of enzyme constraints and proteomics data into such models was first enabled by the GECKO toolbox, allowing the study of phenotypes constrained by protein limitations. Here, we upgrade the toolbox in order to enhance models with enzyme and proteomics constraints for any organism with a compatible GEM reconstruction. With this, enzyme-constrained models for the budding yeasts Saccharomyces cerevisiae, Yarrowia lipolytica and Kluyveromyces marxianus are generated to study their long-term adaptation to several stress factors by incorporation of proteomics data. Predictions reveal that upregulation and high saturation of enzymes in amino acid metabolism are common across organisms and conditions, suggesting the relevance of metabolic robustness in contrast to optimal protein utilization as a cellular objective for microbial growth under stress and nutrient-limited conditions. The functionality of GECKO is expanded with an automated framework for continuous and version-controlled update of enzyme-constrained GEMs, also producing such models for Escherichia coli and Homo sapiens. In this work, we facilitate the utilization of enzyme-constrained GEMs in basic science, metabolic engineering and synthetic biology purposes.
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Affiliation(s)
- Iván Domenzain
- Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden
- Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden
| | - Benjamín Sánchez
- Department of Biotechnology and Biomedicine, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
| | - Mihail Anton
- Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden
- Department of Biology and Biological Engineering, National Bioinformatics Infrastructure Sweden, Science for Life Laboratory, Chalmers University of Technology, Kemivägen 10, SE-412 58, Gothenburg, Sweden
| | - Eduard J Kerkhoven
- Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden
- Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden
| | - Aarón Millán-Oropeza
- Plateforme d'analyse protéomique Paris Sud-Ouest (PAPPSO), INRAE, MICALIS Institute, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Céline Henry
- Plateforme d'analyse protéomique Paris Sud-Ouest (PAPPSO), INRAE, MICALIS Institute, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Verena Siewers
- Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden
- Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden
| | - John P Morrissey
- School of Microbiology, Environmental Research Institute and APC Microbiome Ireland, University College Cork, T12 K8AF, Cork, Ireland
| | - Nikolaus Sonnenschein
- Department of Biotechnology and Biomedicine, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
| | - Jens Nielsen
- Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden.
- Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden.
- BioInnovation Institute, Ole Maaløes Vej 3, 2200, Copenhagen, Denmark.
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15
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Environment Constrains Fitness Advantages of Division of Labor in Microbial Consortia Engineered for Metabolite Push or Pull Interactions. mSystems 2022; 7:e0005122. [PMID: 35762764 PMCID: PMC9426560 DOI: 10.1128/msystems.00051-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fitness benefits from division of labor are well documented in microbial consortia, but the dependency of the benefits on environmental context is poorly understood. Two synthetic Escherichia coli consortia were built to test the relationships between exchanged organic acid, local environment, and opportunity costs of different metabolic strategies. Opportunity costs quantify benefits not realized due to selecting one phenotype over another. The consortia catabolized glucose and exchanged either acetic or lactic acid to create producer-consumer food webs. The organic acids had different inhibitory properties and different opportunity costs associated with their positions in central metabolism. The exchanged metabolites modulated different consortial dynamics. The acetic acid-exchanging (AAE) consortium had a “push” interaction motif where acetic acid was secreted faster by the producer than the consumer imported it, while the lactic acid-exchanging (LAE) consortium had a “pull” interaction motif where the consumer imported lactic acid at a comparable rate to its production. The LAE consortium outperformed wild-type (WT) batch cultures under the environmental context of weakly buffered conditions, achieving a 55% increase in biomass titer, a 51% increase in biomass per proton yield, an 86% increase in substrate conversion, and the complete elimination of by-product accumulation all relative to the WT. However, the LAE consortium had the trade-off of a 42% lower specific growth rate. The AAE consortium did not outperform the WT in any considered performance metric. Performance advantages of the LAE consortium were sensitive to environment; increasing the medium buffering capacity negated the performance advantages compared to WT. IMPORTANCE Most naturally occurring microorganisms persist in consortia where metabolic interactions are common and often essential to ecosystem function. This study uses synthetic ecology to test how different cellular interaction motifs influence performance properties of consortia. Environmental context ultimately controlled the division of labor performance as shifts from weakly buffered to highly buffered conditions negated the benefits of the strategy. Understanding the limits of division of labor advances our understanding of natural community functioning, which is central to nutrient cycling and provides design rules for assembling consortia used in applied bioprocessing.
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16
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Xie T, Chen M, Nielsen J, Xia J. Multi-omics analyses of the transition to the Crabtree effect in S. cerevisiae reveals a key role for the citric acid shuttle. FEMS Yeast Res 2022; 22:6590040. [PMID: 35595470 DOI: 10.1093/femsyr/foac030] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/30/2022] [Accepted: 05/18/2022] [Indexed: 11/14/2022] Open
Abstract
The Crabtree effect in the yeast, Saccharomyces cerevisiae, has been extensively studied, but only few studies have analyzed the dynamic conditions across the critical specific growth rate where the Crabtree effect sets in. Here, we carried out a multi-omics analysis of S. cerevisiae undergoing a specific growth rate transition from 0.2 h-1 to 0.35 h-1. The extracellular metabolome, the transcriptome and the proteome were analyzed in an 8-hour transition period after the specific growth rate shifted from 0.2 h-1 to 0.35 h-1. The changing trends of both the transcriptome and proteome were analyzed using principal component analysis, which showed that the transcriptome clustered together after 60 min, while the proteome reached steady-state much later. Focusing on central carbon metabolism, we analyzed both the changes in the transcriptome and proteome, and observed an interesting changing pattern in the tricarboxylic acid (TCA) pathway, which indicates an important role for citric acid shuttling across the mitochondrial membrane for α-ketoglutarate accumulation during the transition from respiratory to respiro-fermentative metabolism. This was supported by a change in the oxaloacetate and malate shuttle. Together, our findings shed new light into the onset of the Crabtree effect in S. cerevisiae.
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Affiliation(s)
- Tingting Xie
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Min Chen
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Jens Nielsen
- Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, SE41296, Sweden.,BioInnovation Institute, Ole Maaløes Vej 3, DK2200 Copenhagen N, Denmark
| | - Jianye Xia
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China.,Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
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17
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Elsemman IE, Rodriguez Prado A, Grigaitis P, Garcia Albornoz M, Harman V, Holman SW, van Heerden J, Bruggeman FJ, Bisschops MMM, Sonnenschein N, Hubbard S, Beynon R, Daran-Lapujade P, Nielsen J, Teusink B. Whole-cell modeling in yeast predicts compartment-specific proteome constraints that drive metabolic strategies. Nat Commun 2022; 13:801. [PMID: 35145105 PMCID: PMC8831649 DOI: 10.1038/s41467-022-28467-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 01/27/2022] [Indexed: 01/20/2023] Open
Abstract
When conditions change, unicellular organisms rewire their metabolism to sustain cell maintenance and cellular growth. Such rewiring may be understood as resource re-allocation under cellular constraints. Eukaryal cells contain metabolically active organelles such as mitochondria, competing for cytosolic space and resources, and the nature of the relevant cellular constraints remain to be determined for such cells. Here, we present a comprehensive metabolic model of the yeast cell, based on its full metabolic reaction network extended with protein synthesis and degradation reactions. The model predicts metabolic fluxes and corresponding protein expression by constraining compartment-specific protein pools and maximising growth rate. Comparing model predictions with quantitative experimental data suggests that under glucose limitation, a mitochondrial constraint limits growth at the onset of ethanol formation—known as the Crabtree effect. Under sugar excess, however, a constraint on total cytosolic volume dictates overflow metabolism. Our comprehensive model thus identifies condition-dependent and compartment-specific constraints that can explain metabolic strategies and protein expression profiles from growth rate optimisation, providing a framework to understand metabolic adaptation in eukaryal cells. Metabolically active organelles compete for cytosolic space and resources during metabolism rewiring. Here, the authors develop a computational model of yeast metabolism and resource allocation to predict condition- and compartment-specific proteome constraints that govern metabolic strategies.
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Affiliation(s)
- Ibrahim E Elsemman
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, DK2800, Lyngby, Denmark.,Department of Information Systems, Faculty of Computers and Information, Assiut University, Assiut, Egypt
| | - Angelica Rodriguez Prado
- Systems Biology Lab, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.,Department of Industrial Microbiology, Technical University Delft, Delft, The Netherlands
| | - Pranas Grigaitis
- Systems Biology Lab, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | | | - Victoria Harman
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Stephen W Holman
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Johan van Heerden
- Systems Biology Lab, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Frank J Bruggeman
- Systems Biology Lab, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Mark M M Bisschops
- Department of Industrial Microbiology, Technical University Delft, Delft, The Netherlands
| | - Nikolaus Sonnenschein
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, DK2800, Lyngby, Denmark
| | - Simon Hubbard
- Division of Evolution & Genomic Sciences, University of Manchester, Manchester, UK
| | - Rob Beynon
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Pascale Daran-Lapujade
- Department of Industrial Microbiology, Technical University Delft, Delft, The Netherlands
| | - Jens Nielsen
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, DK2800, Lyngby, Denmark. .,Department of Biology and Biological Engineering, Chalmers University of Technology, SE41296, Gothenburg, Sweden.
| | - Bas Teusink
- Systems Biology Lab, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
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18
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Targeting the ATP synthase in bacterial and fungal pathogens – beyond Mycobacterium tuberculosis. J Glob Antimicrob Resist 2022; 29:29-41. [DOI: 10.1016/j.jgar.2022.01.026] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 01/24/2022] [Accepted: 01/30/2022] [Indexed: 11/23/2022] Open
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19
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Moreno-Paz S, Schmitz J, Martins Dos Santos VAP, Suarez-Diez M. Enzyme-constrained models predict the dynamics of Saccharomyces cerevisiae growth in continuous, batch and fed-batch bioreactors. Microb Biotechnol 2022; 15:1434-1445. [PMID: 35048533 PMCID: PMC9049605 DOI: 10.1111/1751-7915.13995] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 11/23/2021] [Accepted: 12/05/2021] [Indexed: 11/29/2022] Open
Abstract
Genome‐scale, constraint‐based models (GEM) and their derivatives are commonly used to model and gain insights into microbial metabolism. Often, however, their accuracy and predictive power are limited and enable only approximate designs. To improve their usefulness for strain and bioprocess design, we studied here their capacity to accurately predict metabolic changes in response to operational conditions in a bioreactor, as well as intracellular, active reactions. We used flux balance analysis (FBA) and dynamic FBA (dFBA) to predict growth dynamics of the model organism Saccharomyces cerevisiae under different industrially relevant conditions. We compared simulations with the latest developed GEM for this organism (Yeast8) and its enzyme‐constrained version (ecYeast8) herein described with experimental data and found that ecYeast8 outperforms Yeast8 in all the simulations. EcYeast8 was able to predict well‐known traits of yeast metabolism including the onset of the Crabtree effect, the order of substrate consumption during mixed carbon cultivation and production of a target metabolite. We showed how the combination of ecGEM and dFBA links reactor operation and genetic modifications to flux predictions, enabling the prediction of yields and productivities of different strains and (dynamic) production processes. Additionally, we present flux sampling as a tool to analyse flux predictions of ecGEM, of major importance for strain design applications. We showed that constraining protein availability substantially improves accuracy of the description of the metabolic state of the cell under dynamic conditions. This therefore enables more realistic and faithful designs of industrially relevant cell‐based processes and, thus, the usefulness of such models.
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Affiliation(s)
- Sara Moreno-Paz
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Wageningen, The Netherlands
| | - Joep Schmitz
- DSM Biotechnology Center, DSM, Delft, The Netherlands
| | - Vitor A P Martins Dos Santos
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Wageningen, The Netherlands.,Laboratory of Bioprocess Engineering, Wageningen University & Research, Wageningen, The Netherlands.,Lifeglimmer GmbH, Berlin, Germany
| | - Maria Suarez-Diez
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Wageningen, The Netherlands
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20
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Euler C, Mahadevan R. On the design principles of metabolic flux sensing. Biophys J 2022; 121:237-247. [PMID: 34951981 PMCID: PMC8790210 DOI: 10.1016/j.bpj.2021.12.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 10/01/2021] [Accepted: 12/16/2021] [Indexed: 01/21/2023] Open
Abstract
Metabolism is precisely coordinated, with the goal of balancing fluxes to maintain robust growth. However, coordinating fluxes requires information about rates, which can only be inferred through concentrations. While flux-sensitive metabolites have been reported, the design principles underlying such sensing have not been clearly elucidated. Here we use kinetic modeling to show that substrate concentrations of thermodynamically constrained reactions reflect upstream flux and therefore carry information about rates. Then we use untargeted multi-omic data from Escherichia coli and Saccharomyces cerevisiae to show that the concentrations of some metabolites in central carbon metabolism reflect fluxes as a result of thermodynamic constraints. We then establish, using 37 real concentration-flux relationships across both organisms, that in vivo ΔG∘≥-4 kJ/mol is the threshold above which substrates are likely to be sensitive to upstream flux(es).
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Affiliation(s)
- Christian Euler
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Radhakrishnan Mahadevan
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada; Institute for Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.
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21
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Kim M, Sung J, Chia N. Resource-allocation constraint governs structure and function of microbial communities in metabolic modeling. Metab Eng 2022; 70:12-22. [PMID: 34990848 DOI: 10.1016/j.ymben.2021.12.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 12/01/2021] [Accepted: 12/29/2021] [Indexed: 10/19/2022]
Abstract
Predictive modeling tools for assessing microbial communities are important for realizing transformative capabilities of microbiomes in agriculture, ecology, and medicine. Constraint-based community-scale metabolic modeling is unique in its potential for making mechanistic predictions regarding both the structure and function of microbial communities. However, accessing this potential requires an understanding of key physicochemical constraints, which are typically considered on a per-species basis. What is needed is a means of incorporating global constraints relevant to microbial ecology into community models. Resource-allocation constraint, which describes how limited resources should be distributed to different cellular processes, sets limits on the efficiency of metabolic and ecological processes. In this study, we investigate the implications of resource-allocation constraints in community-scale metabolic modeling through a simple mechanism-agnostic implementation of resource-allocation constraints directly at the flux level. By systematically performing single-, two-, and multi-species growth simulations, we show that resource-allocation constraints are indispensable for predicting the structure and function of microbial communities. Our findings call for a scalable workflow for implementing a mechanistic version of resource-allocation constraints to ultimately harness the full potential of community-scale metabolic modeling tools.
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Affiliation(s)
- Minsuk Kim
- Microbiome Program, Center for Individualized Medicine, Mayo Clinic, Rochester, MN, 55905, USA; Division of Surgical Research, Department of Surgery, Mayo Clinic, Rochester, MN, 55905, USA
| | - Jaeyun Sung
- Microbiome Program, Center for Individualized Medicine, Mayo Clinic, Rochester, MN, 55905, USA; Division of Surgical Research, Department of Surgery, Mayo Clinic, Rochester, MN, 55905, USA; Division of Rheumatology, Department of Medicine, Mayo Clinic, Rochester, MN, 55905, USA
| | - Nicholas Chia
- Microbiome Program, Center for Individualized Medicine, Mayo Clinic, Rochester, MN, 55905, USA; Division of Surgical Research, Department of Surgery, Mayo Clinic, Rochester, MN, 55905, USA.
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22
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Taymaz-Nikerel H, Lara AR. Vitreoscilla Haemoglobin: A Tool to Reduce Overflow Metabolism. Microorganisms 2021; 10:microorganisms10010043. [PMID: 35056491 PMCID: PMC8779101 DOI: 10.3390/microorganisms10010043] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/18/2021] [Accepted: 12/20/2021] [Indexed: 11/26/2022] Open
Abstract
Overflow metabolism is a phenomenon extended in nature, ranging from microbial to cancer cells. Accumulation of overflow metabolites pose a challenge for large-scale bioprocesses. Yet, the causes of overflow metabolism are not fully clarified. In this work, the underlying mechanisms, reasons and consequences of overflow metabolism in different organisms have been summarized. The reported effect of aerobic expression of Vitreoscilla haemoglobin (VHb) in different organisms are revised. The use of VHb to reduce overflow metabolism is proposed and studied through flux balance analysis in E. coli at a fixed maximum substrate and oxygen uptake rates. Simulations showed that the presence of VHb increases the growth rate, while decreasing acetate production, in line with the experimental measurements. Therefore, aerobic VHb expression is considered a potential tool to reduce overflow metabolism in cells.
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Affiliation(s)
- Hilal Taymaz-Nikerel
- Department of Genetics and Bioengineering, Istanbul Bilgi University, İstanbul 34060, Turkey;
| | - Alvaro R. Lara
- Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana, Mexico City 05348, Mexico
- Correspondence:
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23
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Dourado H, Mori M, Hwa T, Lercher MJ. On the optimality of the enzyme-substrate relationship in bacteria. PLoS Biol 2021; 19:e3001416. [PMID: 34699521 PMCID: PMC8547704 DOI: 10.1371/journal.pbio.3001416] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 09/17/2021] [Indexed: 11/28/2022] Open
Abstract
Much recent progress has been made to understand the impact of proteome allocation on bacterial growth; much less is known about the relationship between the abundances of the enzymes and their substrates, which jointly determine metabolic fluxes. Here, we report a correlation between the concentrations of enzymes and their substrates in Escherichia coli. We suggest this relationship to be a consequence of optimal resource allocation, subject to an overall constraint on the biomass density: For a cellular reaction network composed of effectively irreversible reactions, maximal reaction flux is achieved when the dry mass allocated to each substrate is equal to the dry mass of the unsaturated (or “free”) enzymes waiting to consume it. Calculations based on this optimality principle successfully predict the quantitative relationship between the observed enzyme and metabolite abundances, parameterized only by molecular masses and enzyme–substrate dissociation constants (Km). The corresponding organizing principle provides a fundamental rationale for cellular investment into different types of molecules, which may aid in the design of more efficient synthetic cellular systems. This study shows that in E. coli, the cellular mass of each metabolite approximately equals the combined mass of the free enzymes waiting to consume it; this simple relationship arises from the optimal utilization of cellular dry mass, and quantitatively describes available experimental data.
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Affiliation(s)
- Hugo Dourado
- Institute for Computer Science and Department of Biology, Heinrich Heine University, Düsseldorf, Germany
| | - Matteo Mori
- Department of Physics, University of California at San Diego, La Jolla, California, United States of America
| | - Terence Hwa
- Department of Physics, University of California at San Diego, La Jolla, California, United States of America
| | - Martin J. Lercher
- Institute for Computer Science and Department of Biology, Heinrich Heine University, Düsseldorf, Germany
- * E-mail:
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24
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Zeng H, Rohani R, Huang WE, Yang A. Understanding and mathematical modelling of cellular resource allocation in microorganisms: a comparative synthesis. BMC Bioinformatics 2021; 22:467. [PMID: 34583645 PMCID: PMC8479906 DOI: 10.1186/s12859-021-04382-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 09/20/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The rising consensus that the cell can dynamically allocate its resources provides an interesting angle for discovering the governing principles of cell growth and metabolism. Extensive efforts have been made in the past decade to elucidate the relationship between resource allocation and phenotypic patterns of microorganisms. Despite these exciting developments, there is still a lack of explicit comparison between potentially competing propositions and a lack of synthesis of inter-related proposals and findings. RESULTS In this work, we have reviewed resource allocation-derived principles, hypotheses and mathematical models to recapitulate important achievements in this area. In particular, the emergence of resource allocation phenomena is deciphered by the putative tug of war between the cellular objectives, demands and the supply capability. Competing hypotheses for explaining the most-studied phenomenon arising from resource allocation, i.e. the overflow metabolism, have been re-examined towards uncovering the potential physiological root cause. The possible link between proteome fractions and the partition of the ribosomal machinery has been analysed through mathematical derivations. Finally, open questions are highlighted and an outlook on the practical applications is provided. It is the authors' intention that this review contributes to a clearer understanding of the role of resource allocation in resolving bacterial growth strategies, one of the central questions in microbiology. CONCLUSIONS We have shown the importance of resource allocation in understanding various aspects of cellular systems. Several important questions such as the physiological root cause of overflow metabolism and the correct interpretation of 'protein costs' are shown to remain open. As the understanding of the mechanisms and utility of resource application in cellular systems further develops, we anticipate that mathematical modelling tools incorporating resource allocation will facilitate the circuit-host design in synthetic biology.
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Affiliation(s)
- Hong Zeng
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University, Beijing, 100048, China
| | - Reza Rohani
- Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, UK
| | - Wei E Huang
- Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, UK
| | - Aidong Yang
- Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, UK.
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25
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Belliveau NM, Chure G, Hueschen CL, Garcia HG, Kondev J, Fisher DS, Theriot JA, Phillips R. Fundamental limits on the rate of bacterial growth and their influence on proteomic composition. Cell Syst 2021; 12:924-944.e2. [PMID: 34214468 PMCID: PMC8460600 DOI: 10.1016/j.cels.2021.06.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 04/12/2021] [Accepted: 06/04/2021] [Indexed: 12/11/2022]
Abstract
Despite abundant measurements of bacterial growth rate, cell size, and protein content, we lack a rigorous understanding of what sets the scale of these quantities and when protein abundances should (or should not) depend on growth rate. Here, we estimate the basic requirements and physical constraints on steady-state growth by considering key processes in cellular physiology across a collection of Escherichia coli proteomic data covering ≈4,000 proteins and 36 growth rates. Our analysis suggests that cells are predominantly tuned for the task of cell doubling across a continuum of growth rates; specific processes do not limit growth rate or dictate cell size. We present a model of proteomic regulation as a function of nutrient supply that reconciles observed interdependences between protein synthesis, cell size, and growth rate and propose that a theoretical inability to parallelize ribosomal synthesis places a firm limit on the achievable growth rate. A record of this paper's transparent peer review process is included in the supplemental information.
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Affiliation(s)
- Nathan M Belliveau
- Department of Biology, Howard Hughes Medical Institute, University of Washington, Seattle, WA 98105, USA
| | - Griffin Chure
- Department of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Christina L Hueschen
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Hernan G Garcia
- Department of Molecular Cell Biology and Department of Physics, University of California Berkeley, Berkeley, CA 94720, USA
| | - Jane Kondev
- Department of Physics, Brandeis University, Waltham, MA 02453, USA
| | - Daniel S Fisher
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Julie A Theriot
- Department of Biology, Howard Hughes Medical Institute, University of Washington, Seattle, WA 98105, USA.
| | - Rob Phillips
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA; Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.
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26
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Chen Y, Nielsen J, Kerkhoven EJ. Proteome Constraints in
Genome‐Scale
Models. Metab Eng 2021. [DOI: 10.1002/9783527823468.ch4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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27
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Kim J, Silva-Rocha R, de Lorenzo V. Picking the right metaphors for addressing microbial systems: economic theory helps understanding biological complexity. Int Microbiol 2021; 24:507-519. [PMID: 34269947 DOI: 10.1007/s10123-021-00194-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/28/2021] [Accepted: 07/01/2021] [Indexed: 11/28/2022]
Abstract
Any descriptive language is necessarily metaphoric and interpretative. Two somewhat overlapping-but not identical-languages have been thoroughly employed in the last decade to address the issue of regulatory complexity in biological systems: the terminology of network theory and the jargon of electric circuitry. These approaches have found many formal equivalences between the layout of extant genetic circuits and the architecture of man-made counterparts. However, these languages still fail to describe accurately key features of biological objects, in particular the diversity of signal-transfer molecules and the diffusion that is inherent to any biochemical system. Furthermore, current formalisms associated with networks and circuits can hardly face the problem of multi-scale regulatory complexity-from single molecules to entire ecosystems. We argue that the language of economic theory might be instrumental not only to portray accurately many features of regulatory networks, but also to unveil aspects of the biological complexity problem that remain opaque to other types of analyses. The main perspective opened by the economic metaphor when applied to control of microbiological activities is a focus on metabolism, not gene selfishness, as the necessary background to make sense of regulatory phenomena. As an example, we analyse and reinterpret the widespread phenomenon of catabolite repression with the formal frame of the consumer's choice theory.
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Affiliation(s)
- Juhyun Kim
- Department of Chemical Engineering, Imperial College London, London, SW7 2AZ, UK
| | - Rafael Silva-Rocha
- Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, 14049-900, Brazil
| | - Víctor de Lorenzo
- Systems Biology Department, Centro Nacional de Biotecnología-CSIC, Campus de Cantoblanco, 28049, Madrid, Spain.
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Zhang L, Li X, Zuo W, Li S, Sun G, Wang W, Yu Y, Huang H. Root exuded low-molecular-weight organic acids affected the phenanthrene degrader differently: A multi-omics study. JOURNAL OF HAZARDOUS MATERIALS 2021; 414:125367. [PMID: 33677320 DOI: 10.1016/j.jhazmat.2021.125367] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/28/2021] [Accepted: 02/07/2021] [Indexed: 06/12/2023]
Abstract
As a class of highly toxic and persistent organic pollutants, polycyclic aromatic hydrocarbons (PAHs) are an increasingly urgent environmental problem. Low-molecular-weight organic acids (LMWOAs) are important factors that regulate the degradation of PAHs by plant rhizosphere microorganisms, which affect the absorption of PAHs by plant roots. However, the comprehensive mechanisms by which LMWOAs influence the biodegradation of PAHs at cellular and omics levels are still unknown. Here, we systematically analyzed the roles of citric, glutaric and oxalic acid in the PAH-degradation process, and investigated the mechanisms through which these three LMWOAs enhance phenanthrene (PHE) biodegradation by B. subtilis ZL09-26. The results showed that LMWOAs can improve the solubility and biodegradation of PHE, enhance cell growth and activity, and relieve membrane and oxidative stress. Citric acid enhanced PHE biodegradation mainly by improving the strain's cell proliferation and activity, while glutaric and oxalic acid accelerated PHE biodegradation mainly by improving the expression of enzymes and providing energy for the cells of B. subtilis ZL09-26. This study provides new insights into rhizospheric bioremediation mechanisms, which may enable the development of new biostimulation techniques to improve the bioremediation of PAHs.
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Affiliation(s)
- Lei Zhang
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China; College of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210009, People's Republic of China
| | - Xiujuan Li
- College of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210009, People's Republic of China
| | - Wenlu Zuo
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China; College of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210009, People's Republic of China
| | - Shuang Li
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China
| | - Gangzheng Sun
- Research Institute of Petroleum Engineering and Technology, Shengli Oilfield Company, Sinopec, Dongying 257067, People's Republic of China
| | - Weidong Wang
- Research Institute of Petroleum Engineering and Technology, Shengli Oilfield Company, Sinopec, Dongying 257067, People's Republic of China
| | - Yadong Yu
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China; College of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210009, People's Republic of China.
| | - He Huang
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China; College of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210009, People's Republic of China.
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29
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Physical bioenergetics: Energy fluxes, budgets, and constraints in cells. Proc Natl Acad Sci U S A 2021; 118:2026786118. [PMID: 34140336 DOI: 10.1073/pnas.2026786118] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Cells are the basic units of all living matter which harness the flow of energy to drive the processes of life. While the biochemical networks involved in energy transduction are well-characterized, the energetic costs and constraints for specific cellular processes remain largely unknown. In particular, what are the energy budgets of cells? What are the constraints and limits energy flows impose on cellular processes? Do cells operate near these limits, and if so how do energetic constraints impact cellular functions? Physics has provided many tools to study nonequilibrium systems and to define physical limits, but applying these tools to cell biology remains a challenge. Physical bioenergetics, which resides at the interface of nonequilibrium physics, energy metabolism, and cell biology, seeks to understand how much energy cells are using, how they partition this energy between different cellular processes, and the associated energetic constraints. Here we review recent advances and discuss open questions and challenges in physical bioenergetics.
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30
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Early Heat Exposure Effects on Proteomic Changes of the Broiler Liver under Acute Heat Stress. Animals (Basel) 2021; 11:ani11051338. [PMID: 34066761 PMCID: PMC8151403 DOI: 10.3390/ani11051338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 05/04/2021] [Accepted: 05/05/2021] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Early heat exposure have been studied in the poultry industry as a method of reducing heat stress (HS) on poultry. However, the results of each study are inconsistent, and it has not been confirmed which mechanisms reduce HS by early heat exposure. Therefore, we tried to confirm the relaxation mechanism through proteomic analysis after applying early and acute heat exposure to broilers. The broilers were divided into three treatments, followed by CC (control group), CH (acute HS at the 35th day), and HH (early heat exposure at the fifth day and acute HS at the 35th day. Liver samples were collected and analyzed for proteomics and functional analysis. Proteins related to various functions, such as carbohydrate metabolism, fatty acid metabolism, energy metabolism, and the oxidation–reduction process, which were dramatically changed by acute HS, and were alleviated similar to the control group by early heat exposure. Through these results, the mechanism by which early heat exposure induces homeostasis during acute HS, and the possibility of the early heat exposure as a method of reducing HS were confirmed. Abstract As environmental temperatures continue to rise, heat stress (HS) is having a negative effect on the livestock industry. In order to solve this problem, many studies have been conducted to reduce HS. Among them, early heat exposure has been suggested as a method for reducing HS in poultry. In this study, we analyzed proteomics and tried to identify the metabolic mechanisms of early heat exposure on acute HS. A total of 48 chicks were separated into three groups: CC (control groups raised at optimum temperature), CH (raised with CC but exposed acute HS at the 35th day), and HH (raised with CC but exposed early heat at the fifth day and acute HS at the 35th day). After the whole period, liver samples were collected for proteomic analysis. A total of 97 differentially expressed proteins were identified by acute HS. Of these, 62 proteins recovered their expression levels by early heat exposure. We used these 62 proteins to determine the protective effects of early heat exposure. Of the various protein-related terms, we focused on the oxidative phosphorylation, fatty acid metabolism, carbohydrate metabolism, and energy production metabolism. Our findings suggest the possibility of early heat exposure effects in acute HS that may be useful in breeding or management techniques for producing broilers with high heat resistance.
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31
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Chen Y, van Pelt‐KleinJan E, van Olst B, Douwenga S, Boeren S, Bachmann H, Molenaar D, Nielsen J, Teusink B. Proteome constraints reveal targets for improving microbial fitness in nutrient-rich environments. Mol Syst Biol 2021; 17:e10093. [PMID: 33821549 PMCID: PMC8022198 DOI: 10.15252/msb.202010093] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 02/26/2021] [Accepted: 03/01/2021] [Indexed: 11/28/2022] Open
Abstract
Cells adapt to different conditions via gene expression that tunes metabolism for maximal fitness. Constraints on cellular proteome may limit such expression strategies and introduce trade-offs. Resource allocation under proteome constraints has explained regulatory strategies in bacteria. It is unclear, however, to what extent these constraints can predict evolutionary changes, especially for microorganisms that evolved under nutrient-rich conditions, i.e., multiple available nitrogen sources, such as Lactococcus lactis. Here, we present a proteome-constrained genome-scale metabolic model of L. lactis (pcLactis) to interpret growth on multiple nutrients. Through integration of proteomics and flux data, in glucose-limited chemostats, the model predicted glucose and arginine uptake as dominant constraints at low growth rates. Indeed, glucose and arginine catabolism were found upregulated in evolved mutants. At high growth rates, pcLactis correctly predicted the observed shutdown of arginine catabolism because limited proteome availability favored lactate for ATP production. Thus, our model-based analysis is able to identify and explain the proteome constraints that limit growth rate in nutrient-rich environments and thus form targets of fitness improvement.
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Affiliation(s)
- Yu Chen
- Department of Biology and Biological EngineeringChalmers University of TechnologyGothenburgSweden
- Novo Nordisk Foundation Center for BiosustainabilityChalmers University of TechnologyGothenburgSweden
| | - Eunice van Pelt‐KleinJan
- TiFNWageningenthe Netherlands
- Systems Biology LabAmsterdam Institute of Molecular and Life Sciences (AIMMS)Vrije Universiteit AmsterdamAmsterdamThe Netherlands
| | - Berdien van Olst
- TiFNWageningenthe Netherlands
- Host‐Microbe InteractomicsWageningen University & ResearchWageningenThe Netherlands
- Laboratory of BiochemistryWageningen University & ResearchWageningenThe Netherlands
| | - Sieze Douwenga
- TiFNWageningenthe Netherlands
- Systems Biology LabAmsterdam Institute of Molecular and Life Sciences (AIMMS)Vrije Universiteit AmsterdamAmsterdamThe Netherlands
| | - Sjef Boeren
- TiFNWageningenthe Netherlands
- Laboratory of BiochemistryWageningen University & ResearchWageningenThe Netherlands
| | - Herwig Bachmann
- TiFNWageningenthe Netherlands
- Systems Biology LabAmsterdam Institute of Molecular and Life Sciences (AIMMS)Vrije Universiteit AmsterdamAmsterdamThe Netherlands
- NIZO Food ResearchEdeThe Netherlands
| | - Douwe Molenaar
- TiFNWageningenthe Netherlands
- Systems Biology LabAmsterdam Institute of Molecular and Life Sciences (AIMMS)Vrije Universiteit AmsterdamAmsterdamThe Netherlands
| | - Jens Nielsen
- Department of Biology and Biological EngineeringChalmers University of TechnologyGothenburgSweden
- Novo Nordisk Foundation Center for BiosustainabilityChalmers University of TechnologyGothenburgSweden
- Novo Nordisk Foundation Center for BiosustainabilityTechnical University of DenmarkLyngbyDenmark
- BioInnovation InstituteCopenhagen NDenmark
| | - Bas Teusink
- TiFNWageningenthe Netherlands
- Systems Biology LabAmsterdam Institute of Molecular and Life Sciences (AIMMS)Vrije Universiteit AmsterdamAmsterdamThe Netherlands
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32
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Millard P, Enjalbert B, Uttenweiler-Joseph S, Portais JC, Létisse F. Control and regulation of acetate overflow in Escherichia coli. eLife 2021; 10:63661. [PMID: 33720011 PMCID: PMC8021400 DOI: 10.7554/elife.63661] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 03/12/2021] [Indexed: 12/21/2022] Open
Abstract
Overflow metabolism refers to the production of seemingly wasteful by-products by cells during growth on glucose even when oxygen is abundant. Two theories have been proposed to explain acetate overflow in Escherichia coli – global control of the central metabolism and local control of the acetate pathway – but neither accounts for all observations. Here, we develop a kinetic model of E. coli metabolism that quantitatively accounts for observed behaviours and successfully predicts the response of E. coli to new perturbations. We reconcile these theories and clarify the origin, control, and regulation of the acetate flux. We also find that, in turns, acetate regulates glucose metabolism by coordinating the expression of glycolytic and TCA genes. Acetate should not be considered a wasteful end-product since it is also a co-substrate and a global regulator of glucose metabolism in E. coli. This has broad implications for our understanding of overflow metabolism.
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Affiliation(s)
- Pierre Millard
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.,MetaToul-MetaboHUB, National Infrastructure of Metabolomics and Fluxomics, Toulouse, France
| | - Brice Enjalbert
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France
| | | | - Jean-Charles Portais
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.,MetaToul-MetaboHUB, National Infrastructure of Metabolomics and Fluxomics, Toulouse, France.,RESTORE, Université de Toulouse, INSERM U1031, CNRS 5070, Université Toulouse III - Paul Sabatier, EFS, Toulouse, France
| | - Fabien Létisse
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.,Université Toulouse III - Paul Sabatier, Toulouse, France
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33
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Regueira A, Lema JM, Mauricio-Iglesias M. Microbial inefficient substrate use through the perspective of resource allocation models. Curr Opin Biotechnol 2021; 67:130-140. [PMID: 33540363 DOI: 10.1016/j.copbio.2021.01.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 01/19/2021] [Accepted: 01/20/2021] [Indexed: 01/15/2023]
Abstract
Microorganisms extract energy from substrates following strategies that may seem suboptimal at first glance. Beyond the so-called yield-rate trade-off, resource allocation models, which focus on assigning different functional roles to the limited number of enzymes that a cell can support, offer a framework to interpret the inefficient substrate use by microorganisms. We review here relevant examples of substrate conversions where a significant part of the available energy is not utilised and how resource allocation models offer a mechanistic interpretation thereof, notably for open mixed cultures. Future developments are identified, in particular, the challenge of considering metabolic flexibility towards uncertain environmental changes instead of strict fixed optimality objectives, with the final goal of increasing the prediction capabilities of resource allocation models. Finally, we highlight the relevance of resource allocation to understand and enable a promising biorefinery platform revolving around lactate, which would increase the flexibility of waste-to-chemical biorefinery schemes.
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Affiliation(s)
- Alberte Regueira
- CRETUS Institute, Department of Chemical Engineering, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
| | - Juan M Lema
- CRETUS Institute, Department of Chemical Engineering, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Miguel Mauricio-Iglesias
- CRETUS Institute, Department of Chemical Engineering, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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34
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McGill SL, Yung Y, Hunt KA, Henson MA, Hanley L, Carlson RP. Pseudomonas aeruginosa reverse diauxie is a multidimensional, optimized, resource utilization strategy. Sci Rep 2021; 11:1457. [PMID: 33446818 PMCID: PMC7809481 DOI: 10.1038/s41598-020-80522-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 12/17/2020] [Indexed: 12/19/2022] Open
Abstract
Pseudomonas aeruginosa is a globally-distributed bacterium often found in medical infections. The opportunistic pathogen uses a different, carbon catabolite repression (CCR) strategy than many, model microorganisms. It does not utilize a classic diauxie phenotype, nor does it follow common systems biology assumptions including preferential consumption of glucose with an 'overflow' metabolism. Despite these contradictions, P. aeruginosa is competitive in many, disparate environments underscoring knowledge gaps in microbial ecology and systems biology. Physiological, omics, and in silico analyses were used to quantify the P. aeruginosa CCR strategy known as 'reverse diauxie'. An ecological basis of reverse diauxie was identified using a genome-scale, metabolic model interrogated with in vitro omics data. Reverse diauxie preference for lower energy, nonfermentable carbon sources, such as acetate or succinate over glucose, was predicted using a multidimensional strategy which minimized resource investment into central metabolism while completely oxidizing substrates. Application of a common, in silico optimization criterion, which maximizes growth rate, did not predict the reverse diauxie phenotypes. This study quantifies P. aeruginosa metabolic strategies foundational to its wide distribution and virulence including its potentially, mutualistic interactions with microorganisms found commonly in the environment and in medical infections.
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Affiliation(s)
- S Lee McGill
- Department of Chemical and Biological Engineering, Center for Biofilm Engineering, Montana State University, Bozeman, MT, 59717, USA.,Department of Microbiology and Immunology, Montana State University, Bozeman, MT, 59717, USA
| | - Yeni Yung
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Kristopher A Hunt
- Department of Chemical and Biological Engineering, Center for Biofilm Engineering, Montana State University, Bozeman, MT, 59717, USA.,Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, 98115, USA
| | - Michael A Henson
- Department of Chemical Engineering, Institute for Applied Life Sciences, University of Massachusetts, Amherst, MA, 01003, USA
| | - Luke Hanley
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Ross P Carlson
- Department of Chemical and Biological Engineering, Center for Biofilm Engineering, Montana State University, Bozeman, MT, 59717, USA. .,Department of Microbiology and Immunology, Montana State University, Bozeman, MT, 59717, USA.
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35
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Dahal S, Zhao J, Yang L. Genome-scale Modeling of Metabolism and Macromolecular Expression and Their Applications. BIOTECHNOL BIOPROC E 2021. [DOI: 10.1007/s12257-020-0061-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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36
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Antoniewicz MR. A guide to metabolic flux analysis in metabolic engineering: Methods, tools and applications. Metab Eng 2020; 63:2-12. [PMID: 33157225 DOI: 10.1016/j.ymben.2020.11.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 10/28/2020] [Accepted: 11/01/2020] [Indexed: 12/22/2022]
Abstract
The field of metabolic engineering is primarily concerned with improving the biological production of value-added chemicals, fuels and pharmaceuticals through the design, construction and optimization of metabolic pathways, redirection of intracellular fluxes, and refinement of cellular properties relevant for industrial bioprocess implementation. Metabolic network models and metabolic fluxes are central concepts in metabolic engineering, as was emphasized in the first paper published in this journal, "Metabolic fluxes and metabolic engineering" (Metabolic Engineering, 1: 1-11, 1999). In the past two decades, a wide range of computational, analytical and experimental approaches have been developed to interrogate the capabilities of biological systems through analysis of metabolic network models using techniques such as flux balance analysis (FBA), and quantify metabolic fluxes using constrained-based modeling approaches such as metabolic flux analysis (MFA) and more advanced experimental techniques based on the use of stable-isotope tracers, i.e. 13C-metabolic flux analysis (13C-MFA). In this review, we describe the basic principles of metabolic flux analysis, discuss current best practices in flux quantification, highlight potential pitfalls and alternative approaches in the application of these tools, and give a broad overview of pragmatic applications of flux analysis in metabolic engineering practice.
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Affiliation(s)
- Maciek R Antoniewicz
- Department of Chemical Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Michigan, Ann Arbor, MI, 48109, USA.
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37
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Toward a systematic design of smart probiotics. Curr Opin Biotechnol 2020; 64:199-209. [DOI: 10.1016/j.copbio.2020.05.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 04/24/2020] [Accepted: 05/07/2020] [Indexed: 12/13/2022]
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38
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Yang DD, Alexander A, Kinnersley M, Cook E, Caudy A, Rosebrock A, Rosenzweig F. Fitness and Productivity Increase with Ecotypic Diversity among Escherichia coli Strains That Coevolved in a Simple, Constant Environment. Appl Environ Microbiol 2020; 86:e00051-20. [PMID: 32060029 PMCID: PMC7117940 DOI: 10.1128/aem.00051-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 02/05/2020] [Indexed: 12/11/2022] Open
Abstract
The productivity of a biological community often correlates with its diversity. In the microbial world this phenomenon can sometimes be explained by positive, density-dependent interactions such as cross-feeding and syntrophy. These metabolic interactions help account for the astonishing variety of microbial life and drive many of the biogeochemical cycles without which life as we know it could not exist. While it is difficult to recapitulate experimentally how these interactions evolved among multiple taxa, we can explore in the laboratory how they arise within one. These experiments provide insight into how different bacterial ecotypes evolve and from these, possibly new "species." We have previously shown that in a simple, constant environment a single clone of Escherichia coli can give rise to a consortium of genetically and phenotypically differentiated strains, in effect, a set of ecotypes, that coexist by cross-feeding. We marked these different ecotypes and their shared ancestor by integrating fluorescent protein into their genomes and then used flow cytometry to show that each evolved strain is more fit than the shared ancestor, that pairs of evolved strains are fitter still, and that the entire consortium is the fittest of all. We further demonstrate that the rank order of fitness values agrees with estimates of yield, indicating that an experimentally evolved consortium more efficiently converts primary and secondary resources to offspring than its ancestor or any member acting in isolation.IMPORTANCE Polymicrobial consortia occur in both environmental and clinical settings. In many cases, diversity and productivity correlate in these consortia, especially when sustained by positive, density-dependent interactions. However, the evolutionary history of such entities is typically obscure, making it difficult to establish the relative fitness of consortium partners and to use those data to illuminate the diversity-productivity relationship. Here, we dissect an Escherichia coli consortium that evolved under continuous glucose limitation in the laboratory from a single common ancestor. We show that a partnership consisting of cross-feeding ecotypes is better able to secure primary and secondary resources and to convert those resources to offspring than the ancestral clone. Such interactions may be a prelude to a special form of syntrophy and are likely determinants of microbial community structure in nature, including those having clinical significance such as chronic infections.
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Affiliation(s)
- Dong-Dong Yang
- Division Biological Sciences, University of Montana, Missoula, Montana, USA
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Ashley Alexander
- Division Biological Sciences, University of Montana, Missoula, Montana, USA
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Margie Kinnersley
- Division Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Emily Cook
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Amy Caudy
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - Adam Rosebrock
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - Frank Rosenzweig
- Division Biological Sciences, University of Montana, Missoula, Montana, USA
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia, USA
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39
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Kamrad S, Grossbach J, Rodríguez‐López M, Mülleder M, Townsend S, Cappelletti V, Stojanovski G, Correia‐Melo C, Picotti P, Beyer A, Ralser M, Bähler J. Pyruvate kinase variant of fission yeast tunes carbon metabolism, cell regulation, growth and stress resistance. Mol Syst Biol 2020; 16:e9270. [PMID: 32319721 PMCID: PMC7175467 DOI: 10.15252/msb.20199270] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 03/12/2020] [Accepted: 03/18/2020] [Indexed: 12/11/2022] Open
Abstract
Cells balance glycolysis with respiration to support their metabolic needs in different environmental or physiological contexts. With abundant glucose, many cells prefer to grow by aerobic glycolysis or fermentation. Using 161 natural isolates of fission yeast, we investigated the genetic basis and phenotypic effects of the fermentation-respiration balance. The laboratory and a few other strains depended more on respiration. This trait was associated with a single nucleotide polymorphism in a conserved region of Pyk1, the sole pyruvate kinase in fission yeast. This variant reduced Pyk1 activity and glycolytic flux. Replacing the "low-activity" pyk1 allele in the laboratory strain with the "high-activity" allele was sufficient to increase fermentation and decrease respiration. This metabolic rebalancing triggered systems-level adjustments in the transcriptome and proteome and in cellular traits, including increased growth and chronological lifespan but decreased resistance to oxidative stress. Thus, low Pyk1 activity does not lead to a growth advantage but to stress tolerance. The genetic tuning of glycolytic flux may reflect an adaptive trade-off in a species lacking pyruvate kinase isoforms.
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Affiliation(s)
- Stephan Kamrad
- Molecular Biology of Metabolism LaboratoryThe Francis Crick InstituteLondonUK
- Department of Genetics, Evolution & EnvironmentInstitute of Healthy AgeingUniversity College LondonLondonUK
| | - Jan Grossbach
- CECADMedical Faculty & Faculty of Mathematics and Natural SciencesUniversity of CologneCologneGermany
| | - Maria Rodríguez‐López
- Department of Genetics, Evolution & EnvironmentInstitute of Healthy AgeingUniversity College LondonLondonUK
| | - Michael Mülleder
- Molecular Biology of Metabolism LaboratoryThe Francis Crick InstituteLondonUK
- Charité University MedicineBerlinGermany
| | - StJohn Townsend
- Molecular Biology of Metabolism LaboratoryThe Francis Crick InstituteLondonUK
- Department of Genetics, Evolution & EnvironmentInstitute of Healthy AgeingUniversity College LondonLondonUK
| | - Valentina Cappelletti
- Department of BiologyInstitute of Molecular Systems BiologyETH ZurichZurichSwitzerland
| | - Gorjan Stojanovski
- Department of Genetics, Evolution & EnvironmentInstitute of Healthy AgeingUniversity College LondonLondonUK
| | - Clara Correia‐Melo
- Molecular Biology of Metabolism LaboratoryThe Francis Crick InstituteLondonUK
| | - Paola Picotti
- Department of BiologyInstitute of Molecular Systems BiologyETH ZurichZurichSwitzerland
| | - Andreas Beyer
- CECADMedical Faculty & Faculty of Mathematics and Natural SciencesUniversity of CologneCologneGermany
- Center for Molecular Medicine CologneCologneGermany
| | - Markus Ralser
- Molecular Biology of Metabolism LaboratoryThe Francis Crick InstituteLondonUK
- Charité University MedicineBerlinGermany
| | - Jürg Bähler
- Department of Genetics, Evolution & EnvironmentInstitute of Healthy AgeingUniversity College LondonLondonUK
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40
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Bridging substrate intake kinetics and bacterial growth phenotypes with flux balance analysis incorporating proteome allocation. Sci Rep 2020; 10:4283. [PMID: 32152336 PMCID: PMC7062752 DOI: 10.1038/s41598-020-61174-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Accepted: 02/24/2020] [Indexed: 11/08/2022] Open
Abstract
Empirical kinetic models such as the Monod equation have been widely applied to relate the cell growth with substrate availability. The Monod equation shares a similar form with the mechanistically-based Michaelis-Menten kinetics for enzymatic processes, which has provoked long-standing and un-concluded conjectures on their relationship. In this work, we integrated proteome allocation principles into a Flux Balance Analysis (FBA) model of Escherichia coli, which quantitatively revealed potential mechanisms that underpin the phenomenological Monod parameters: the maximum specific growth rate could be dictated by the abundance of growth-controlling proteome and growth-pertinent proteome cost; more importantly, the Monod constant (Ks) was shown to relate to the Michaelis constant for substrate transport (Km,g), with the link being dependent on the cell's metabolic strategy. Besides, the proposed model was able to predict glucose uptake rate at given external glucose concentration through the size of available proteome resource for substrate transport and its enzymatic cost, while growth rate and acetate overflow were accurately simulated for two E. coli strains. Bridging the enzymatic kinetics of substrate intake and overall growth phenotypes, this work offers a mechanistic interpretation to the empirical Monod law, and demonstrates the potential of coupling local and global cellular constrains in predictive modelling.
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Abstract
The biological fitness of microbes is largely determined by the rate with which they replicate their biomass composition. Mathematical models that maximize this balanced growth rate while accounting for mass conservation, reaction kinetics, and limits on dry mass per volume are inevitably non-linear. Here, we develop a general theory for such models, termed Growth Balance Analysis (GBA), which provides explicit expressions for protein concentrations, fluxes, and growth rates. These variables are functions of the concentrations of cellular components, for which we calculate marginal fitness costs and benefits that are related to metabolic control coefficients. At maximal growth rate, the net benefits of all concentrations are equal. Based solely on physicochemical constraints, GBA unveils fundamental quantitative principles of cellular resource allocation and growth; it accurately predicts the relationship between growth rates and ribosome concentrations in E. coli and yeast and between growth rate and dry mass density in E. coli.
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Affiliation(s)
- Hugo Dourado
- Institute for Computer Science & Department of Biology, Heinrich Heine University, 40221, Düsseldorf, Germany
| | - Martin J Lercher
- Institute for Computer Science & Department of Biology, Heinrich Heine University, 40221, Düsseldorf, Germany.
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Schütze A, Benndorf D, Püttker S, Kohrs F, Bettenbrock K. The Impact of ackA, pta, and ackA-pta Mutations on Growth, Gene Expression and Protein Acetylation in Escherichia coli K-12. Front Microbiol 2020; 11:233. [PMID: 32153530 PMCID: PMC7047895 DOI: 10.3389/fmicb.2020.00233] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 01/31/2020] [Indexed: 01/06/2023] Open
Abstract
Acetate is a characteristic by-product of Escherichia coli K-12 growing in batch cultures with glucose, both under aerobic as well as anaerobic conditions. While the reason underlying aerobic acetate production is still under discussion, during anaerobic growth acetate production is important for ATP generation by substrate level phosphorylation. Under both conditions, acetate is produced by a pathway consisting of the enzyme phosphate acetyltransferase (Pta) producing acetyl-phosphate from acetyl-coenzyme A, and of the enzyme acetate kinase (AckA) producing acetate from acetyl-phosphate, a reaction that is coupled to the production of ATP. Mutants in the AckA-Pta pathway differ from each other in the potential to produce and accumulate acetyl-phosphate. In the publication at hand, we investigated different mutants in the acetate pathway, both under aerobic as well as anaerobic conditions. While under aerobic conditions only small changes in growth rate were observed, all acetate mutants showed severe reduction in growth rate and changes in the by-product pattern during anaerobic growth. The AckA- mutant showed the most severe growth defect. The glucose uptake rate and the ATP concentration were strongly reduced in this strain. This mutant exhibited also changes in gene expression. In this strain, the atoDAEB operon was significantly upregulated under anaerobic conditions hinting to the production of acetoacetate. During anaerobic growth, protein acetylation increased significantly in the ackA mutant. Acetylation of several enzymes of glycolysis and central metabolism, of aspartate carbamoyl transferase, methionine synthase, catalase and of proteins involved in translation was increased. Supplementation of methionine and uracil eliminated the additional growth defect of the ackA mutant. The data show that anaerobic, fermentative growth of mutants in the AckA-Pta pathway is reduced but still possible. Growth reduction can be explained by the lack of an important ATP generating pathway of mixed acid fermentation. An ackA deletion mutant is more severely impaired than pta or ackA-pta deletion mutants. This is most probably due to the production of acetyl-P in the ackA mutant, leading to increased protein acetylation.
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Affiliation(s)
- Andrea Schütze
- Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
| | - Dirk Benndorf
- Bioprocess Engineering, Otto von Guericke University, Magdeburg, Germany
| | - Sebastian Püttker
- Bioprocess Engineering, Otto von Guericke University, Magdeburg, Germany
| | - Fabian Kohrs
- Bioprocess Engineering, Otto von Guericke University, Magdeburg, Germany
| | - Katja Bettenbrock
- Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
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43
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Quantitative Connection between Cell Size and Growth Rate by Phospholipid Metabolism. Cells 2020; 9:cells9020391. [PMID: 32046235 PMCID: PMC7072380 DOI: 10.3390/cells9020391] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 02/04/2020] [Indexed: 11/16/2022] Open
Abstract
The processes involved in cell growth are extremely complicated even for a single cell organism such as Escherichia coli, while the relationship between growth rate and cell size is simple. We aimed to reveal the systematic link between them from the aspect of the genome-scale metabolic network. Since the growth rate reflects metabolic rates of bacteria and the cell size relates to phospholipid synthesis, a part of bacterial metabolic networks, we calculated the cell length from the cardiolipin synthesis rate, where the cardiolipin synthesis reaction is able to represent the phospholipid metabolism of Escherichia coli in the exponential growth phase. Combined with the flux balance analysis, it enables us to predict cell length and to examine the quantitative relationship between cell length and growth rate. By simulating bacteria growing in various nutrient media with the flux balance analysis and calculating the corresponding cell length, we found that the increase of the synthesis rate of phospholipid, the cell width, and the protein fraction in membranes caused the increase of cell length with growth rate. Different tendencies of phospholipid synthesis rate changing with growth rate result in different relationships between cell length and growth rate. The effects of gene deletions on cell size and growth rate are also examined. Knocking out the genes, such as Δ tktA, Δ tktB, Δ yqaB, Δ pgm, and Δ cysQ, affects growth rate largely while affecting cell length slightly. Results of this method are in good agreement with experiments.
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de Groot DH, Lischke J, Muolo R, Planqué R, Bruggeman FJ, Teusink B. The common message of constraint-based optimization approaches: overflow metabolism is caused by two growth-limiting constraints. Cell Mol Life Sci 2020; 77:441-453. [PMID: 31758233 PMCID: PMC7010627 DOI: 10.1007/s00018-019-03380-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 11/05/2019] [Accepted: 11/12/2019] [Indexed: 12/14/2022]
Abstract
Living cells can express different metabolic pathways that support growth. The criteria that determine which pathways are selected in which environment remain unclear. One recurrent selection is overflow metabolism: the simultaneous usage of an ATP-efficient and -inefficient pathway, shown for example in Escherichia coli, Saccharomyces cerevisiae and cancer cells. Many models, based on different assumptions, can reproduce this observation. Therefore, they provide no conclusive evidence which mechanism is causing overflow metabolism. We compare the mathematical structure of these models. Although ranging from flux balance analyses to self-fabricating metabolism and expression models, we can rewrite all models into one standard form. We conclude that all models predict overflow metabolism when two, model-specific, growth-limiting constraints are hit. This is consistent with recent theory. Thus, identifying these two constraints is essential for understanding overflow metabolism. We list all imposed constraints by these models, so that they can hopefully be tested in future experiments.
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Affiliation(s)
- Daan H de Groot
- Systems Bioinformatics, AIMMS, Vrije Universiteit Amsterdam, 1081HZ, Amsterdam, The Netherlands.
| | - Julia Lischke
- Systems Bioinformatics, AIMMS, Vrije Universiteit Amsterdam, 1081HZ, Amsterdam, The Netherlands
| | - Riccardo Muolo
- Systems Bioinformatics, AIMMS, Vrije Universiteit Amsterdam, 1081HZ, Amsterdam, The Netherlands
| | - Robert Planqué
- Department of Mathematics, Vrije Universiteit Amsterdam, 1081HV, Amsterdam, The Netherlands
| | - Frank J Bruggeman
- Systems Bioinformatics, AIMMS, Vrije Universiteit Amsterdam, 1081HZ, Amsterdam, The Netherlands
| | - Bas Teusink
- Systems Bioinformatics, AIMMS, Vrije Universiteit Amsterdam, 1081HZ, Amsterdam, The Netherlands
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Park H, McGill SL, Arnold AD, Carlson RP. Pseudomonad reverse carbon catabolite repression, interspecies metabolite exchange, and consortial division of labor. Cell Mol Life Sci 2020; 77:395-413. [PMID: 31768608 PMCID: PMC7015805 DOI: 10.1007/s00018-019-03377-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 11/04/2019] [Accepted: 11/12/2019] [Indexed: 10/25/2022]
Abstract
Microorganisms acquire energy and nutrients from dynamic environments, where substrates vary in both type and abundance. The regulatory system responsible for prioritizing preferred substrates is known as carbon catabolite repression (CCR). Two broad classes of CCR have been documented in the literature. The best described CCR strategy, referred to here as classic CCR (cCCR), has been experimentally and theoretically studied using model organisms such as Escherichia coli. cCCR phenotypes are often used to generalize universal strategies for fitness, sometimes incorrectly. For instance, extremely competitive microorganisms, such as Pseudomonads, which arguably have broader global distributions than E. coli, have achieved their success using metabolic strategies that are nearly opposite of cCCR. These organisms utilize a CCR strategy termed 'reverse CCR' (rCCR), because the order of preferred substrates is nearly reverse that of cCCR. rCCR phenotypes prefer organic acids over glucose, may or may not select preferred substrates to optimize growth rates, and do not allocate intracellular resources in a manner that produces an overflow metabolism. cCCR and rCCR have traditionally been interpreted from the perspective of monocultures, even though most microorganisms live in consortia. Here, we review the basic tenets of the two CCR strategies and consider these phenotypes from the perspective of resource acquisition in consortia, a scenario that surely influenced the evolution of cCCR and rCCR. For instance, cCCR and rCCR metabolism are near mirror images of each other; when considered from a consortium basis, the complementary properties of the two strategies can mitigate direct competition for energy and nutrients and instead establish cooperative division of labor.
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Affiliation(s)
- Heejoon Park
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, USA
- Center for Biofilm Engineering, Montana State University, Bozeman, USA
| | - S Lee McGill
- Department of Microbiology and Immunology, Montana State University, Bozeman, USA
- Center for Biofilm Engineering, Montana State University, Bozeman, USA
| | - Adrienne D Arnold
- Department of Microbiology and Immunology, Montana State University, Bozeman, USA
- Center for Biofilm Engineering, Montana State University, Bozeman, USA
| | - Ross P Carlson
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, USA.
- Department of Microbiology and Immunology, Montana State University, Bozeman, USA.
- Center for Biofilm Engineering, Montana State University, Bozeman, USA.
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46
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McKinlay JB, Cook GM, Hards K. Microbial energy management-A product of three broad tradeoffs. Adv Microb Physiol 2020; 77:139-185. [PMID: 34756210 DOI: 10.1016/bs.ampbs.2020.09.001] [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] [Indexed: 12/11/2022]
Abstract
Wherever thermodynamics allows, microbial life has evolved to transform and harness energy. Microbial life thus abounds in the most unexpected places, enabled by profound metabolic diversity. Within this diversity, energy is transformed primarily through variations on a few core mechanisms. Energy is further managed by the physiological processes of cell growth and maintenance that use energy. Some aspects of microbial physiology are streamlined for energetic efficiency while other aspects seem suboptimal or even wasteful. We propose that the energy that a microbe harnesses and devotes to growth and maintenance is a product of three broad tradeoffs: (i) economic, trading enzyme synthesis or operational cost for functional benefit, (ii) environmental, trading optimization for a single environment for adaptability to multiple environments, and (iii) thermodynamic, trading energetic yield for forward metabolic flux. Consideration of these tradeoffs allows one to reconcile features of microbial physiology that seem to opposingly promote either energetic efficiency or waste.
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Affiliation(s)
- James B McKinlay
- Department of Biology, Indiana University, Bloomington, IN, United States.
| | - Gregory M Cook
- Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland, New Zealand
| | - Kiel Hards
- Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland, New Zealand
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47
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Bajic D, Sanchez A. The ecology and evolution of microbial metabolic strategies. Curr Opin Biotechnol 2019; 62:123-128. [PMID: 31670179 DOI: 10.1016/j.copbio.2019.09.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 08/21/2019] [Accepted: 09/06/2019] [Indexed: 12/21/2022]
Abstract
Free-living microbes are generally capable of growing on multiple different nutrients. Some of those nutrients are used simultaneously, while others are used sequentially. The pattern of nutrient preferences and co-utilization defines the metabolic strategy of a microorganism. Metabolic strategies can substantially affect ecological interactions between species, but their evolution and distribution across the tree of life remain poorly characterized. We discuss how the confluence of better computational models of genotype-phenotype maps and high-throughput experimental tools can help us fill gaps in our knowledge and incorporate metabolic strategies into quantitative predictive models of microbial consortia.
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Affiliation(s)
- Djordje Bajic
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06511, United States; Microbial Sciences Institute, Yale University West Campus, West Haven, CT 06516, United States
| | - Alvaro Sanchez
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06511, United States; Microbial Sciences Institute, Yale University West Campus, West Haven, CT 06516, United States.
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48
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Kim J, Darlington A, Salvador M, Utrilla J, Jiménez JI. Trade-offs between gene expression, growth and phenotypic diversity in microbial populations. Curr Opin Biotechnol 2019; 62:29-37. [PMID: 31580950 PMCID: PMC7208540 DOI: 10.1016/j.copbio.2019.08.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 08/15/2019] [Accepted: 08/20/2019] [Indexed: 12/13/2022]
Abstract
Limitations in molecular resources for gene expression influence bacterial physiology. Bacteria optimise trade-offs between resource allocation and growth. Resource allocation plays a role in the emergence of phenotypic heterogeneity. Trade-offs between bet-hedging and growth can be harnessed in biotechnology.
Bacterial cells have a limited number of resources that can be allocated for gene expression. The intracellular competition for these resources has an impact on the cell physiology. Bacteria have evolved mechanisms to optimize resource allocation in a variety of scenarios, showing a trade-off between the resources used to maximise growth (e.g. ribosome synthesis) and the rest of cellular functions. Limitations in gene expression also play a role in generating phenotypic diversity, which is advantageous in fluctuating environments, at the expenses of decreasing growth rates. Our current understanding of these trade-offs can be exploited for biotechnological applications benefiting from the selective manipulation of the allocation of resources.
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Affiliation(s)
- Juhyun Kim
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7XH, United Kingdom
| | | | - Manuel Salvador
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7XH, United Kingdom
| | - José Utrilla
- Centre for Genomic Sciences, Universidad Nacional Autónoma de México, Campus Morelos, Av. Universidad s/n Col. Chamilpa 62210, Cuernavaca, Mexico
| | - José I Jiménez
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7XH, United Kingdom.
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49
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Shimizu K, Matsuoka Y. Redox rebalance against genetic perturbations and modulation of central carbon metabolism by the oxidative stress regulation. Biotechnol Adv 2019; 37:107441. [PMID: 31472206 DOI: 10.1016/j.biotechadv.2019.107441] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 08/04/2019] [Accepted: 08/23/2019] [Indexed: 12/11/2022]
Abstract
The micro-aerophilic organisms and aerobes as well as yeast and higher organisms have evolved to gain energy through respiration (via oxidative phosphorylation), thereby enabling them to grow much faster than anaerobes. However, during respiration, reactive oxygen species (ROSs) are inherently (inevitably) generated, and threaten the cell's survival. Therefore, living organisms (or cells) must furnish the potent defense systems to keep such ROSs at harmless level, where the cofactor balance plays crucial roles. Namely, NADH is the source of energy generation (catabolism) in the respiratory chain reactions, through which ROSs are generated, while NADPH plays important roles not only for the cell synthesis (anabolism) but also for detoxifying ROSs. Therefore, the cell must rebalance the redox ratio by modulating the fluxes of the central carbon metabolism (CCM) by regulating the multi-level regulation machinery upon genetic perturbations and the change in the growth conditions. Here, we discuss about how aerobes accomplish such cofactor homeostasis against redox perturbations. In particular, we consider how single-gene mutants (including pgi, pfk, zwf, gnd and pyk mutants) modulate their metabolisms in relation to cofactor rebalance (and also by adaptive laboratory evolution). We also discuss about how the overproduction of NADPH (by the pathway gene mutation) can be utilized for the efficient production of useful value-added chemicals such as medicinal compounds, polyhydroxyalkanoates, and amino acids, all of which require NADPH in their synthetic pathways. We then discuss about the metabolic responses against oxidative stress, where αketoacids play important roles not only for the coordination between catabolism and anabolism, but also for detoxifying ROSs by non-enzymatic reactions, as well as for reducing the production of ROSs by repressing the activities of the TCA cycle and respiration (via carbon catabolite repression). Thus, we discuss about the mechanisms (basic strategies) that modulate the metabolism from respiration to respiro-fermentative metabolism causing overflow, based on the role of Pyk activity, affecting the NADPH production at the oxidative pentose phosphate (PP) pathway, and the roles of αketoacids for the change in the source of energy generation from the oxidative phosphorylation to the substrate level phosphorylation.
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Affiliation(s)
- Kazuyuki Shimizu
- Kyushu institute of Technology, Iizuka, Fukuoka 820-8502, Japan; Institute of Advanced Biosciences, Keio university, Tsuruoka, Yamagata 997-0017, Japan.
| | - Yu Matsuoka
- Kyushu institute of Technology, Iizuka, Fukuoka 820-8502, Japan.
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50
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Nilsson A, Nielsen J, Palsson BO. Metabolic Models of Protein Allocation Call for the Kinetome. Cell Syst 2019; 5:538-541. [PMID: 29284126 DOI: 10.1016/j.cels.2017.11.013] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Revised: 10/09/2017] [Accepted: 11/20/2017] [Indexed: 11/26/2022]
Abstract
The flux of metabolites in the living cell depend on enzyme activities. Recently, many metabolic phenotypes have been explained by computer models that incorporate enzyme activity data. To move further, the scientific community needs to measure the kinetics of all enzymes in a systematic way.
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Affiliation(s)
- Avlant Nilsson
- Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, SE412 96 Gothenburg, Sweden
| | - Jens Nielsen
- Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, SE412 96 Gothenburg, Sweden; Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Hørsholm DK2970, Denmark.
| | - Bernhard O Palsson
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Hørsholm DK2970, Denmark; Departments of Bioengineering and Pediatrics, Mail Code 412, University of California, San Diego, La Jolla, CA 92093, USA
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