Maeda2019_AmmoniumTransportAssimilation
Ontology highlight
ABSTRACT:
SUBMITTER: 
Kazuhiro Maeda
PROVIDER: MODEL1901090001 | BioModels | 2019-04-15
REPOSITORIES: BioModels
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Project description:This a model from the article:
The multifarious short-term regulation of ammonium assimilation of Escherichia coli: dissection using an in silico replica.
Bruggeman FJ, Boogerd FC, Westerhoff HV. FEBS J.
2005 Apr;272(8):1965-85. 15819889
,
Abstract:
Ammonium assimilation in Escherichia coli is regulated through multiple mechanisms (metabolic, signal transduction leading to covalent modification, transcription, and translation), which (in-)directly affect the activities of its two ammonium-assimilating enzymes, i.e. glutamine synthetase (GS) and glutamate dehydrogenase (GDH). Much is known about the kinetic properties of the components of the regulatory network that these enzymes are part of, but the ways in which, and the extents to which the network leads to subtle and quasi-intelligent regulation are unappreciated. To determine whether our present knowledge of the interactions between and the kinetic properties of the components of this network is complete - to the extent that when integrated in a kinetic model it suffices to calculate observed physiological behaviour - we now construct a kinetic model of this network, based on all of the kinetic data on the components that is available in the literature. We use this model to analyse regulation of ammonium assimilation at various carbon statuses for cells that have adapted to low and high ammonium concentrations. We show how a sudden increase in ammonium availability brings about a rapid redirection of the ammonium assimilation flux from GS/glutamate synthase (GOGAT) to GDH. The extent of redistribution depends on the nitrogen and carbon status of the cell. We develop a method to quantify the relative importance of the various regulators in the network. We find the importance is shared among regulators. We confirm that the adenylylation state of GS is the major regulator but that a total of 40% of the regulation is mediated by ADP (22%), glutamate (10%), glutamine (7%) and ATP (1%). The total steady-state ammonium assimilation flux is remarkably robust against changes in the ammonium concentration, but the fluxes through GS and GDH are completely nonrobust. Gene expression of GOGAT above a threshold value makes expression of GS under ammonium-limited conditions, and of GDH under glucose-limited conditions, sufficient for ammonium assimilation.
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2024-09-02 | BIOMD0000000217 | BioModels
Project description:Amino acid assimilation and metabolism are crucial for bacterial growth and survival and this is particularly obvious for lactic acid bacteria (LAB) that are generally auxotroph for various amino acids. However, amino acid assimilation is poorly characterized and a complete description of the response during amino acid starvation is still lacking in LAB. In this context, the global response of the LAB model Lactococcus lactis was characterized during isoleucine starvation in batch culture. The stress was imposed by isoleucine natural consumption in an initially rich chemically defined medium. Dynamic analyses were performed both using transcriptomic and proteomic approaches. The response was found to occur gradually and could be divided into three major parts that were firstly deduced from transcriptomic analysis and generally corroborated by proteomic results: (i) a global repression of biogenic processes (transcription, translation, and carbon metabolism and transport), (ii) a specific response related to the limiting nutrient (numerous pathways belonging to carbon or nitrogen metabolism and leading to isoleucine supply were activated) and (iii) an additional response connected to oxidative stress (induction of aerobic metabolism, electron transport, thioredoxin metabolism and pyruvate dehydrogenase). The involvement of various regulatory mechanisms such as growth rate regulation, stringent response, CodY, GlnR, and CcpA regulations, was discussed on the basis of transcriptomic data comparisons. Above the full description of L. lactis isoleucine starvation response, this work additionally provided a complex but realistic outlook of the regulation network involved in isoleucine starvation. Such integrated and comparative approach will allow, by its implementation to other regulations and environmental conditions, the whole regulatory network of L. lactis or any other microorganism to be deciphered.
2011-09-22 | GSE12962 | GEO
Project description:Amino acid assimilation and metabolism are crucial for bacterial growth and survival and this is particularly obvious for lactic acid bacteria (LAB) that are generally auxotroph for various amino acids. However, amino acid assimilation is poorly characterized and a complete description of the response during amino acid starvation is still lacking in LAB. In this context, the global response of the LAB model Lactococcus lactis was characterized during isoleucine starvation in batch culture. The stress was imposed by isoleucine natural consumption in an initially rich chemically defined medium. Dynamic analyses were performed both using transcriptomic and proteomic approaches. The response was found to occur gradually and could be divided into three major parts that were firstly deduced from transcriptomic analysis and generally corroborated by proteomic results: (i) a global repression of biogenic processes (transcription, translation, and carbon metabolism and transport), (ii) a specific response related to the limiting nutrient (numerous pathways belonging to carbon or nitrogen metabolism and leading to isoleucine supply were activated) and (iii) an additional response connected to oxidative stress (induction of aerobic metabolism, electron transport, thioredoxin metabolism and pyruvate dehydrogenase). The involvement of various regulatory mechanisms such as growth rate regulation, stringent response, CodY, GlnR, and CcpA regulations, was discussed on the basis of transcriptomic data comparisons. Above the full description of L. lactis isoleucine starvation response, this work additionally provided a complex but realistic outlook of the regulation network involved in isoleucine starvation. Such integrated and comparative approach will allow, by its implementation to other regulations and environmental conditions, the whole regulatory network of L. lactis or any other microorganism to be deciphered. Batch cultivation of Lactococcus lactis IL1403 were carried out on a chemically defined medium and under controlled conditions (30 °C, pH 6.6, nitrogen atmosphere). Cell samples were harvested at steady state. Total RNA was extracted from these samples and radiolabelled cDNA were prepared and hybridized on nylon arrays. 1948 amplicons specific of Lactococcus lactis IL1403 genes were spotted twice on the array. Samples corresponding to various growth rates were analyzed simultaneously and 3 independent repetitions were performed.
2011-09-21 | E-GEOD-12962 | biostudies-arrayexpress
Project description:Mammalian cells adapt their functional state in response to external signals in form of ligands that bind receptors on the cell-surface. Mechanistically, this involves signal-processing through a complex network of molecular interactions that govern transcription factor activity patterns. Computer simulations of the information flow through this network could help predict cellular responses in health and disease. Here we develop a recurrent neural network framework constrained by prior knowledge of the signaling network with ligand-concentrations as input and transcription factor -activity as output. Applied to synthetic data, it predicts unseen test-data (Pearson correlation r=0.98) and the effects of gene knockouts (r=0.8). We stimulate macrophages with 59 different ligands, with and without addition of lipopolysaccharide, and collect transcriptomics data. The framework predicts this data under cross-validation (r=0.8) and knockout simulations suggest a role for RIPK1 in modulating the lipopolysaccharide response. This work demonstrates the feasibility of genome-scale simulations of intracellular signaling.
2022-05-09 | GSE202515 | GEO
Project description:The gas-1(fc21) mutation affects the 49 kD subunit of complex I, decreasing the rate of complex I-dependent oxidative phosphorylation. This is a model for human mitochondrial respiratory chain disease. NAD+ and PPAR-modifying drugs may confer benefits with respect to lifespan in these short-lived mutant worms. Analysis of gas-1(fc21) electron transport chain complex I mutants treated either starting in development or in young adulthood only with nicotinic acid (1 mM), resveratrol (50 microM), rosiglitazone (5 mM) or fenofibrate (14 microM) is presented. The goal is to detect transcriptional changes in clusters of genes using gene set enrichment analysis to explain treament effects in these mutant worms.
2014-08-13 | GSE57626 | GEO
Project description:The identification of changes in transcriptional regulation during priming and differentiation of embryonic stem (ES) cells towards the endoderm lineage. Specific populations of ES cells, either primed or committed to endoderm, were isolated and subjected to global nuclear run on sequencing (GRO-Seq). The hHex-Venus (HV) reporter ES cell line, HVJu5.1 (Canham et al., 2010) was used to isolate HV- and HV+ ES cells. Primed ES cells were identified based on the expression of the HV marker in addition to the cell surface marker of undifferentiated ES cells, SSEA-1, (the lower and upper 25% of SSEA-1+, HV expressing cells). When challenged to differentiate, HV- ES cells are primed towards an epiblast fate, while HV+ ES cells are primed towards primitive endoderm. However, these populations are considered primed, rather than committed, as they will readily interconvert when re-introduced into standard ES cell culture conditions. ES cells were grown in self-renewing conditions (GMEM, LIF, 10% FCS, plated on gelatin coated dishes). Endoderm was obtained by differentiating ES cells in medium without the cytokine LIF for 5 days. The HV+, SSEA-1- differentiated fraction was then sorted and represents an early stage in endoderm differentiation.
2022-01-03 | GSE58503 | GEO
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Project description:Glucose uptake in Escherichia coli had been studied extensively, but the lack of basic information of glucose uptake systems in C. acetobutylicum has limited the understanding of glucose assimilation in this strain. There is a main glucose transporter which is very efficient for glucose uptake and the maltose, mannose and galactose transport systems are also able to transport glucose into cytoplasm of E.coli. Therefore, it is very interesting to investigate whether a similar glucose transport mechanism exists in C. acetobutylicum.
2022-12-28 | E-MTAB-12054 | biostudies-arrayexpress
Project description:Objectives <br> Type 1 interferons (IFN-I) are implicated in the pathogenesis of systemic lupus erythematosus (SLE), but most studies have only reported the effect of IFN-I on mixed cell populations. We aimed to define modules of IFN-I associated genes in purified leukocyte populations and use these as a basis for a detailed comparative analysis. <br>Methods<br>CD4+ and CD8+ T-cells, monocytes and neutrophils were purified from patients with SLE, other immune-mediated diseases and healthy volunteers (HV)and gene expression determined by microarray. Modules of IFN-I associated genes were defined using weighted gene coexpression network analysis. The composition and expression of these modules was analysed.<br>Results<br>1,150 of 1,288 IFN-I associated genes were specific to myeloid subsets, compared with 11 genes unique to T-cells. IFN-I genes were more highly expressed in myeloid subsets compared to T-cells. A subset of neutrophil samples from HV and conditions not classically associated with IFN-I signatures displayed increased IFN-I gene expression, whereas upregulation of IFN-I associated genes in T-cells was restricted to SLE.<br>Conclusions<br>Given the broad upregulation of IFN-I genes in neutrophils including in some HV, investigators reporting IFN-I signatures on the basis of whole blood samples should be cautious about interpreting this as evidence of bona fide IFN-I mediated pathology. Instead, specific upregulation of IFN-I associated genes in T-cells may be a useful biomarker and a further mechanism by which elevated IFN-I contributes to autoimmunity in SLE.
2016-06-01 | E-MTAB-2713 | biostudies-arrayexpress
Project description:We used mass spectrometry-based proteomics to unravel anaplastic lymphoma kinase (ALK) signaling in the ALK and MYCN amplified neuroblastoma cell line, NB1. We specifically measured the ALK phosphoproteome upon siRNA depletion of ALK and upon ALK inhibition using the ALK-targeting small-molecule inhibitor lorlatinib. For quantitative phosphoproteomics we used a tandem mass tag (TMT)-based approach. Conditions for the TMT 11-plex setup is specified below. For each siRNA depletion experiment, NB1 cells were treated with siRNA (80 nM; as specified below) for 48 hours prior to stimulation with 0.1% DMSO for 30 minutes. For inhibitor treatment, NB1 cells were treated for 30 minutes with either 10 microM or 10 nM lorlatinib. The experimental treatment conditions and TMT11-plex labeling are specified below: 126: siControl replicate 1, 0.1% DMSO 127N: siControl replicate 2, 0.1% DMSO 127C: siControl replicate 3, 0.1% DMSO 128N: siALK sequence 1, 0.1% DMSO 128C: siALK sequence 2, 0.1% DMSO 129N: siALK mix of sequence 1 and 2, 0.1% DMSO 129C: 10 microM lorlatinib replicate 1 130N: 10 microM lorlatinib replicate 2 130C: 10 microM lorlatinib replicate 3 131N: 10 nM lorlatinib replicate 1 131C: 10 nM lorlatinib replicate 2
2018-11-21 | PXD009477 | Pride