151
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Multiple Functions of Glutamate Uptake via Meningococcal GltT-GltM L-Glutamate ABC Transporter in Neisseria meningitidis Internalization into Human Brain Microvascular Endothelial Cells. Infect Immun 2015; 83:3555-67. [PMID: 26099588 DOI: 10.1128/iai.00654-15] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 06/17/2015] [Indexed: 12/30/2022] Open
Abstract
We previously reported that Neisseria meningitidis internalization into human brain microvasocular endothelial cells (HBMEC) was triggered by the influx of extracellular L-glutamate via the GltT-GltM L-glutamate ABC transporter, but the underlying mechanism remained unclear. We found that the ΔgltT ΔgltM invasion defect in assay medium (AM) was alleviated in AM without 10% fetal bovine serum (FBS) [AM(-S)]. The alleviation disappeared again in AM(-S) supplemented with 500 μM glutamate. Glutamate uptake by the ΔgltT ΔgltM mutant was less efficient than that by the wild-type strain, but only upon HBMEC infection. We also observed that both GltT-GltM-dependent invasion and accumulation of ezrin, a key membrane-cytoskeleton linker, were more pronounced when N. meningitidis formed larger colonies on HBMEC under physiological glutamate conditions. These results suggested that GltT-GltM-dependent meningococcal internalization into HBMEC might be induced by the reduced environmental glutamate concentration upon infection. Furthermore, we found that the amount of glutathione within the ΔgltT ΔgltM mutant was much lower than that within the wild-type N. meningitidis strain only upon HBMEC infection and was correlated with intracellular survival. Considering that the L-glutamate obtained via GltT-GltM is utilized as a nutrient in host cells, l-glutamate uptake via GltT-GltM plays multiple roles in N. meningitidis internalization into HBMEC.
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152
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van der Stel AX, van Mourik A, Łaniewski P, van Putten JPM, Jagusztyn-Krynicka EK, Wösten MMSM. The Campylobacter jejuni RacRS two-component system activates the glutamate synthesis by directly upregulating γ-glutamyltranspeptidase (GGT). Front Microbiol 2015; 6:567. [PMID: 26097472 PMCID: PMC4456614 DOI: 10.3389/fmicb.2015.00567] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 05/24/2015] [Indexed: 11/15/2022] Open
Abstract
The highly conserved enzyme γ-glutamyltranspeptidase (GGT) plays an important role in metabolism of glutathione and glutamine. Yet, the regulation of ggt transcription in prokaryotes is poorly understood. In the human pathogen Campylobacter jejuni, GGT is important as it contributes to persistent colonization of the gut. Here we show that the GGT activity in C. jejuni is dependent on a functional RacRS (reduced ability to colonize) two-component system. Electrophoretic mobility shift and luciferase reporter assays indicate that the response regulator RacR binds to a promoter region ~80 bp upstream of the ggt transcriptional start site, which contains a recently identified RacR DNA binding consensus sequence. RacR needs to be phosphorylated to activate the transcription of the ggt gene, which is the case under low oxygen conditions in presence of alternative electron acceptors. A functional GGT and RacR are needed to allow C. jejuni to grow optimally on glutamine as sole carbon source under RacR inducing conditions. However, when additional carbon sources are present C. jejuni is capable of utilizing glutamine independently of GGT. RacR is the first prokaryotic transcription factor known to directly up-regulate both the cytoplasmic [glutamine-2-oxoglutarate aminotransferase (GOGAT)] as well as the periplasmic (GGT) production of glutamate.
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Affiliation(s)
| | - Andries van Mourik
- Department of Infectious Diseases and Immunology, Utrecht University, Utrecht Netherlands
| | - Paweł Łaniewski
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw Poland
| | - Jos P M van Putten
- Department of Infectious Diseases and Immunology, Utrecht University, Utrecht Netherlands
| | - Elżbieta K Jagusztyn-Krynicka
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw Poland
| | - Marc M S M Wösten
- Department of Infectious Diseases and Immunology, Utrecht University, Utrecht Netherlands
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153
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The bacterial phosphoenolpyruvate:carbohydrate phosphotransferase system: regulation by protein phosphorylation and phosphorylation-dependent protein-protein interactions. Microbiol Mol Biol Rev 2015; 78:231-56. [PMID: 24847021 DOI: 10.1128/mmbr.00001-14] [Citation(s) in RCA: 281] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The bacterial phosphoenolpyruvate (PEP):carbohydrate phosphotransferase system (PTS) carries out both catalytic and regulatory functions. It catalyzes the transport and phosphorylation of a variety of sugars and sugar derivatives but also carries out numerous regulatory functions related to carbon, nitrogen, and phosphate metabolism, to chemotaxis, to potassium transport, and to the virulence of certain pathogens. For these different regulatory processes, the signal is provided by the phosphorylation state of the PTS components, which varies according to the availability of PTS substrates and the metabolic state of the cell. PEP acts as phosphoryl donor for enzyme I (EI), which, together with HPr and one of several EIIA and EIIB pairs, forms a phosphorylation cascade which allows phosphorylation of the cognate carbohydrate bound to the membrane-spanning EIIC. HPr of firmicutes and numerous proteobacteria is also phosphorylated in an ATP-dependent reaction catalyzed by the bifunctional HPr kinase/phosphorylase. PTS-mediated regulatory mechanisms are based either on direct phosphorylation of the target protein or on phosphorylation-dependent interactions. For regulation by PTS-mediated phosphorylation, the target proteins either acquired a PTS domain by fusing it to their N or C termini or integrated a specific, conserved PTS regulation domain (PRD) or, alternatively, developed their own specific sites for PTS-mediated phosphorylation. Protein-protein interactions can occur with either phosphorylated or unphosphorylated PTS components and can either stimulate or inhibit the function of the target proteins. This large variety of signal transduction mechanisms allows the PTS to regulate numerous proteins and to form a vast regulatory network responding to the phosphorylation state of various PTS components.
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154
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σ54-Dependent Response to Nitrogen Limitation and Virulence in Burkholderia cenocepacia Strain H111. Appl Environ Microbiol 2015; 81:4077-89. [PMID: 25841012 DOI: 10.1128/aem.00694-15] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 03/31/2015] [Indexed: 11/20/2022] Open
Abstract
Members of the genus Burkholderia are versatile bacteria capable of colonizing highly diverse environmental niches. In this study, we investigated the global response of the opportunistic pathogen Burkholderia cenocepacia H111 to nitrogen limitation at the transcript and protein expression levels. In addition to a classical response to nitrogen starvation, including the activation of glutamine synthetase, PII proteins, and the two-component regulatory system NtrBC, B. cenocepacia H111 also upregulated polyhydroxybutyrate (PHB) accumulation and exopolysaccharide (EPS) production in response to nitrogen shortage. A search for consensus sequences in promoter regions of nitrogen-responsive genes identified a σ(54) consensus sequence. The mapping of the σ(54) regulon as well as the characterization of a σ(54) mutant suggests an important role of σ(54) not only in control of nitrogen metabolism but also in the virulence of this organism.
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155
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Matsuoka Y, Shimizu K. Current status and future perspectives of kinetic modeling for the cell metabolism with incorporation of the metabolic regulation mechanism. BIORESOUR BIOPROCESS 2015. [DOI: 10.1186/s40643-014-0031-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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156
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Gerhardt EC, Rodrigues TE, Müller-Santos M, Pedrosa FO, Souza EM, Forchhammer K, Huergo LF. The Bacterial signal transduction protein GlnB regulates the committed step in fatty acid biosynthesis by acting as a dissociable regulatory subunit of acetyl-CoA carboxylase. Mol Microbiol 2015; 95:1025-35. [DOI: 10.1111/mmi.12912] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2014] [Indexed: 11/30/2022]
Affiliation(s)
- Edileusa C.M. Gerhardt
- Instituto Nacional de Ciência e Tecnologia da Fixação Biológica de Nitrogênio, Departamento de Bioquímica e Biologia Molecular; Universidade Federal do Paraná; CEP 81531-990 CP 19046 Curitiba PR Brazil
- Interfakultäres Institut für Mikrobiologie und Infektionsmedizin der Eberhard-Karls Universität Tübingen; Auf der Morgenstelle 28 Tübingen 72076 Germany
| | - Thiago E. Rodrigues
- Instituto Nacional de Ciência e Tecnologia da Fixação Biológica de Nitrogênio, Departamento de Bioquímica e Biologia Molecular; Universidade Federal do Paraná; CEP 81531-990 CP 19046 Curitiba PR Brazil
| | - Marcelo Müller-Santos
- Instituto Nacional de Ciência e Tecnologia da Fixação Biológica de Nitrogênio, Departamento de Bioquímica e Biologia Molecular; Universidade Federal do Paraná; CEP 81531-990 CP 19046 Curitiba PR Brazil
| | - Fabio O. Pedrosa
- Instituto Nacional de Ciência e Tecnologia da Fixação Biológica de Nitrogênio, Departamento de Bioquímica e Biologia Molecular; Universidade Federal do Paraná; CEP 81531-990 CP 19046 Curitiba PR Brazil
| | - Emanuel M. Souza
- Instituto Nacional de Ciência e Tecnologia da Fixação Biológica de Nitrogênio, Departamento de Bioquímica e Biologia Molecular; Universidade Federal do Paraná; CEP 81531-990 CP 19046 Curitiba PR Brazil
| | - Karl Forchhammer
- Interfakultäres Institut für Mikrobiologie und Infektionsmedizin der Eberhard-Karls Universität Tübingen; Auf der Morgenstelle 28 Tübingen 72076 Germany
| | - Luciano F. Huergo
- Instituto Nacional de Ciência e Tecnologia da Fixação Biológica de Nitrogênio, Departamento de Bioquímica e Biologia Molecular; Universidade Federal do Paraná; CEP 81531-990 CP 19046 Curitiba PR Brazil
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157
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Shimizu K. Metabolic Regulation and Coordination of the Metabolism in Bacteria in Response to a Variety of Growth Conditions. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2015; 155:1-54. [PMID: 25712586 DOI: 10.1007/10_2015_320] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Living organisms have sophisticated but well-organized regulation system. It is important to understand the metabolic regulation mechanisms in relation to growth environment for the efficient design of cell factories for biofuels and biochemicals production. Here, an overview is given for carbon catabolite regulation, nitrogen regulation, ion, sulfur, and phosphate regulations, stringent response under nutrient starvation as well as oxidative stress regulation, redox state regulation, acid-shock, heat- and cold-shock regulations, solvent stress regulation, osmoregulation, and biofilm formation, and quorum sensing focusing on Escherichia coli metabolism and others. The coordinated regulation mechanisms are of particular interest in getting insight into the principle which governs the cell metabolism. The metabolism is controlled by both enzyme-level regulation and transcriptional regulation via transcription factors such as cAMP-Crp, Cra, Csr, Fis, P(II)(GlnB), NtrBC, CysB, PhoR/B, SoxR/S, Fur, MarR, ArcA/B, Fnr, NarX/L, RpoS, and (p)ppGpp for stringent response, where the timescales for enzyme-level and gene-level regulations are different. Moreover, multiple regulations are coordinated by the intracellular metabolites, where fructose 1,6-bisphosphate (FBP), phosphoenolpyruvate (PEP), and acetyl-CoA (AcCoA) play important roles for enzyme-level regulation as well as transcriptional control, while α-ketoacids such as α-ketoglutaric acid (αKG), pyruvate (PYR), and oxaloacetate (OAA) play important roles for the coordinated regulation between carbon source uptake rate and other nutrient uptake rate such as nitrogen or sulfur uptake rate by modulation of cAMP via Cya.
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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.
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158
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Fagard M, Launay A, Clément G, Courtial J, Dellagi A, Farjad M, Krapp A, Soulié MC, Masclaux-Daubresse C. Nitrogen metabolism meets phytopathology. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:5643-56. [PMID: 25080088 DOI: 10.1093/jxb/eru323] [Citation(s) in RCA: 123] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Nitrogen (N) is essential for life and is a major limiting factor of plant growth. Because soils frequently lack sufficient N, large quantities of inorganic N fertilizers are added to soils for crop production. However, nitrate, urea, and ammonium are a major source of global pollution, because much of the N that is not taken up by plants enters streams, groundwater, and lakes, where it affects algal production and causes an imbalance in aquatic food webs. Many agronomical data indicate that the higher use of N fertilizers during the green revolution had an impact on the incidence of crop diseases. In contrast, examples in which a decrease in N fertilization increases disease severity are also reported, indicating that there is a complex relationship linking N uptake and metabolism and the disease infection processes. Thus, although it is clear that N availability affects disease, the underlying mechanisms remain unclear. The aim of this review is to describe current knowledge of the mechanisms that link plant N status to the plant's response to pathogen infection and to the virulence and nutritional status of phytopathogens.
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Affiliation(s)
- Mathilde Fagard
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France AgroParisTech, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France
| | - Alban Launay
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France AgroParisTech, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France
| | - Gilles Clément
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France AgroParisTech, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France
| | - Julia Courtial
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France AgroParisTech, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France
| | - Alia Dellagi
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France AgroParisTech, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France
| | - Mahsa Farjad
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France AgroParisTech, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France
| | - Anne Krapp
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France AgroParisTech, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France
| | - Marie-Christine Soulié
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France AgroParisTech, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France
| | - Céline Masclaux-Daubresse
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France AgroParisTech, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France
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159
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Amrani A, Bergon A, Holota H, Tamburini C, Garel M, Ollivier B, Imbert J, Dolla A, Pradel N. Transcriptomics reveal several gene expression patterns in the piezophile Desulfovibrio hydrothermalis in response to hydrostatic pressure. PLoS One 2014; 9:e106831. [PMID: 25215865 PMCID: PMC4162548 DOI: 10.1371/journal.pone.0106831] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 08/01/2014] [Indexed: 11/24/2022] Open
Abstract
RNA-seq was used to study the response of Desulfovibrio hydrothermalis, isolated from a deep-sea hydrothermal chimney on the East-Pacific Rise at a depth of 2,600 m, to various hydrostatic pressure growth conditions. The transcriptomic datasets obtained after growth at 26, 10 and 0.1 MPa identified only 65 differentially expressed genes that were distributed among four main categories: aromatic amino acid and glutamate metabolisms, energy metabolism, signal transduction, and unknown function. The gene expression patterns suggest that D. hydrothermalis uses at least three different adaptation mechanisms, according to a hydrostatic pressure threshold (HPt) that was estimated to be above 10 MPa. Both glutamate and energy metabolism were found to play crucial roles in these mechanisms. Quantitation of the glutamate levels in cells revealed its accumulation at high hydrostatic pressure, suggesting its role as a piezolyte. ATP measurements showed that the energy metabolism of this bacterium is optimized for deep-sea life conditions. This study provides new insights into the molecular mechanisms linked to hydrostatic pressure adaptation in sulfate-reducing bacteria.
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Affiliation(s)
- Amira Amrani
- Aix-Marseille Université, Université du Sud Toulon-Var, CNRS/INSU, IRD, MIO, UM110, Marseille, France
- Aix-Marseille Université, CNRS, LCB-UMR7283, Marseille, France
| | - Aurélie Bergon
- Inserm, U1090, TGML/TAGC, Marseille, France
- Aix Marseille Université, UMR_S 1090, TGML/TAGC, Marseille, France
| | - Hélène Holota
- Inserm, U1090, TGML/TAGC, Marseille, France
- Aix Marseille Université, UMR_S 1090, TGML/TAGC, Marseille, France
| | - Christian Tamburini
- Aix-Marseille Université, Université du Sud Toulon-Var, CNRS/INSU, IRD, MIO, UM110, Marseille, France
| | - Marc Garel
- Aix-Marseille Université, Université du Sud Toulon-Var, CNRS/INSU, IRD, MIO, UM110, Marseille, France
| | - Bernard Ollivier
- Aix-Marseille Université, Université du Sud Toulon-Var, CNRS/INSU, IRD, MIO, UM110, Marseille, France
| | - Jean Imbert
- Inserm, U1090, TGML/TAGC, Marseille, France
- Aix Marseille Université, UMR_S 1090, TGML/TAGC, Marseille, France
| | - Alain Dolla
- Aix-Marseille Université, CNRS, LCB-UMR7283, Marseille, France
- * E-mail: (AD); (NP)
| | - Nathalie Pradel
- Aix-Marseille Université, Université du Sud Toulon-Var, CNRS/INSU, IRD, MIO, UM110, Marseille, France
- * E-mail: (AD); (NP)
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160
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Scott M, Klumpp S, Mateescu EM, Hwa T. Emergence of robust growth laws from optimal regulation of ribosome synthesis. Mol Syst Biol 2014; 10:747. [PMID: 25149558 PMCID: PMC4299513 DOI: 10.15252/msb.20145379] [Citation(s) in RCA: 262] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Bacteria must constantly adapt their growth to changes in nutrient availability; yet despite
large-scale changes in protein expression associated with sensing, adaptation, and processing
different environmental nutrients, simple growth laws connect the ribosome abundance and the growth
rate. Here, we investigate the origin of these growth laws by analyzing the features of ribosomal
regulation that coordinate proteome-wide expression changes with cell growth in a variety of
nutrient conditions in the model organism Escherichia coli. We identify
supply-driven feedforward activation of ribosomal protein synthesis as the key regulatory motif
maximizing amino acid flux, and autonomously guiding a cell to achieve optimal growth in different
environments. The growth laws emerge naturally from the robust regulatory strategy underlying growth
rate control, irrespective of the details of the molecular implementation. The study highlights the
interplay between phenomenological modeling and molecular mechanisms in uncovering fundamental
operating constraints, with implications for endogenous and synthetic design of microorganisms.
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Affiliation(s)
- Matthew Scott
- Department of Applied Mathematics, University of Waterloo, Waterloo, ON, Canada
| | - Stefan Klumpp
- Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Eduard M Mateescu
- Department of Physics and Center for Theoretical Biological Physics, University of California, San Diego La Jolla, CA, USA
| | - Terence Hwa
- Department of Physics and Center for Theoretical Biological Physics, University of California, San Diego La Jolla, CA, USA Institute for Theoretical Studies, ETH Zurich, Zurich, Switzerland
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161
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Westerhoff HV, Brooks AN, Simeonidis E, García-Contreras R, He F, Boogerd FC, Jackson VJ, Goncharuk V, Kolodkin A. Macromolecular networks and intelligence in microorganisms. Front Microbiol 2014; 5:379. [PMID: 25101076 PMCID: PMC4106424 DOI: 10.3389/fmicb.2014.00379] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 07/05/2014] [Indexed: 11/13/2022] Open
Abstract
Living organisms persist by virtue of complex interactions among many components organized into dynamic, environment-responsive networks that span multiple scales and dimensions. Biological networks constitute a type of information and communication technology (ICT): they receive information from the outside and inside of cells, integrate and interpret this information, and then activate a response. Biological networks enable molecules within cells, and even cells themselves, to communicate with each other and their environment. We have become accustomed to associating brain activity - particularly activity of the human brain - with a phenomenon we call "intelligence." Yet, four billion years of evolution could have selected networks with topologies and dynamics that confer traits analogous to this intelligence, even though they were outside the intercellular networks of the brain. Here, we explore how macromolecular networks in microbes confer intelligent characteristics, such as memory, anticipation, adaptation and reflection and we review current understanding of how network organization reflects the type of intelligence required for the environments in which they were selected. We propose that, if we were to leave terms such as "human" and "brain" out of the defining features of "intelligence," all forms of life - from microbes to humans - exhibit some or all characteristics consistent with "intelligence." We then review advances in genome-wide data production and analysis, especially in microbes, that provide a lens into microbial intelligence and propose how the insights derived from quantitatively characterizing biomolecular networks may enable synthetic biologists to create intelligent molecular networks for biotechnology, possibly generating new forms of intelligence, first in silico and then in vivo.
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Affiliation(s)
- Hans V. Westerhoff
- Department of Molecular Cell Physiology, Vrije Universiteit AmsterdamAmsterdam, Netherlands
- Manchester Centre for Integrative Systems Biology, The University of ManchesterManchester, UK
- Synthetic Systems Biology, University of AmsterdamAmsterdam, Netherlands
| | - Aaron N. Brooks
- Institute for Systems BiologySeattle, WA, USA
- Molecular and Cellular Biology Program, University of WashingtonSeattle, WA, USA
| | - Evangelos Simeonidis
- Institute for Systems BiologySeattle, WA, USA
- Luxembourg Centre for Systems Biomedicine, University of LuxembourgEsch-sur-Alzette, Luxembourg
| | | | - Fei He
- Department of Automatic Control and Systems Engineering, The University of SheffieldSheffield, UK
| | - Fred C. Boogerd
- Department of Molecular Cell Physiology, Vrije Universiteit AmsterdamAmsterdam, Netherlands
| | | | - Valeri Goncharuk
- Netherlands Institute for NeuroscienceAmsterdam, Netherlands
- Russian Cardiology Research CenterMoscow, Russia
- Department of Medicine, Center for Alzheimer and Neurodegenerative Research, University of AlbertaEdmonton, AB, Canada
| | - Alexey Kolodkin
- Institute for Systems BiologySeattle, WA, USA
- Luxembourg Centre for Systems Biomedicine, University of LuxembourgEsch-sur-Alzette, Luxembourg
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162
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Abstract
Beyond fuelling cellular activities with building blocks and energy, metabolism also integrates environmental conditions into intracellular signals. The underlying regulatory network is complex and multifaceted: it ranges from slow interactions, such as changing gene expression, to rapid ones, such as the modulation of protein activity via post-translational modification or the allosteric binding of small molecules. In this Review, we outline the coordination of common metabolic tasks, including nutrient uptake, central metabolism, the generation of energy, the supply of amino acids and protein synthesis. Increasingly, a set of key metabolites is recognized to control individual regulatory circuits, which carry out specific functions of information input and regulatory output. Such a modular view of microbial metabolism facilitates an intuitive understanding of the molecular mechanisms that underlie cellular decision making.
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163
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Zurauskienė J, Kirk P, Thorne T, Pinney J, Stumpf M. Derivative processes for modelling metabolic fluxes. ACTA ACUST UNITED AC 2014; 30:1892-8. [PMID: 24578401 PMCID: PMC4071196 DOI: 10.1093/bioinformatics/btu069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Motivation: One of the challenging questions in modelling biological systems is to characterize the functional forms of the processes that control and orchestrate molecular and cellular phenotypes. Recently proposed methods for the analysis of metabolic pathways, for example, dynamic flux estimation, can only provide estimates of the underlying fluxes at discrete time points but fail to capture the complete temporal behaviour. To describe the dynamic variation of the fluxes, we additionally require the assumption of specific functional forms that can capture the temporal behaviour. However, it also remains unclear how to address the noise which might be present in experimentally measured metabolite concentrations. Results: Here we propose a novel approach to modelling metabolic fluxes: derivative processes that are based on multiple-output Gaussian processes (MGPs), which are a flexible non-parametric Bayesian modelling technique. The main advantages that follow from MGPs approach include the natural non-parametric representation of the fluxes and ability to impute the missing data in between the measurements. Our derivative process approach allows us to model changes in metabolite derivative concentrations and to characterize the temporal behaviour of metabolic fluxes from time course data. Because the derivative of a Gaussian process is itself a Gaussian process, we can readily link metabolite concentrations to metabolic fluxes and vice versa. Here we discuss how this can be implemented in an MGP framework and illustrate its application to simple models, including nitrogen metabolism in Escherichia coli. Availability and implementation: R code is available from the authors upon request. Contact:j.norkunaite@imperial.ac.uk; m.stumpf@imperial.ac.uk Supplementary information:Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Justina Zurauskienė
- Theoretical Systems Biology Group, Centre for Bioinformatics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Paul Kirk
- Theoretical Systems Biology Group, Centre for Bioinformatics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Thomas Thorne
- Theoretical Systems Biology Group, Centre for Bioinformatics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - John Pinney
- Theoretical Systems Biology Group, Centre for Bioinformatics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Michael Stumpf
- Theoretical Systems Biology Group, Centre for Bioinformatics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
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