Response of Lactococcus lactis to isoleucine starvation
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ABSTRACT:
ORGANISM(S): Lactococcus lactis
PROVIDER: GSE4872 | GEO | 2008/02/23
SECONDARY ACCESSION(S): PRJNA95935
REPOSITORIES: GEO
Similar Datasets
Project description:For the first time in Lactococcus lactis, amino acid starvation response was characterized. The natural imposition of isoleucine starvation, by its consumption during growth, associated to transcript profiling, allowed defining exhaustively this stress stimulon. It consisted of a general induction of nitrogen metabolism (amino acid biosynthesis and transport, proteolytic system and proteases), a strong repression of genes encoding major physiological activities (translation, transcription, carbon metabolism, purine and pyrimidine biosynthesis and fatty acid metabolism) and the induction of unexpected cross responses to acid, osmotic and oxidative stresses. Keywords: stress response, time course Isoleucine starvation was imposed by the consumption of this amino acid during the growth of Lactococcus lactis IL1403 on ILV0.1 medium (CDM with ten-fold reduced concentrations of isoleucine, leucine and valine) and under controlled conditions (30 °C, pH 6.6, nitrogen atmosphere). Cell samples were harvested in exponential phase and after 30 min, 1.7 h and 3.5 h of isoleucine starvation. Total RNA was extracted from these samples and radiolabelled cDNA were prepared and hybridized on nylon arrays. 2053 amplicons specific of Lactococcus lactis IL1403 genes were spotted twice on the array. The 4 time-points were analyzed simultaneously and 3 independent repetitions were performed.
2010-06-25 | E-GEOD-4872 | biostudies-arrayexpress
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: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:Transcriptional regulation of branched-chain amino acid metabolism in Saccharomyces cerevisiae involves two key regulator proteins, Leu3p and Gcn4p. Leu3p is a pathway-specific regulator, known to regulate six genes involved in branched-chain amino acid metabolism and one gene in nitrogen assimilation. Gcn4p is a global regulator, involved in the general response to amino acid and purine starvation. To investigate the contribution of Leu3p in regulation of gene expression, a leu3D strain was compared to an isogenic reference strain using DNA-microarray analysis. This comparison was performed for both glucose-grown, ammonium-limited and ethanol-limited, ammonium-excess chemostat cultures. In ethanol-limited cultures, absence of Leu3p led to reduced transcript levels of six of the seven established Leu3p target genes, but did not affect key physiological parameters. In ammonium-limited cultures, absence of Leu3p caused a drastic decrease in storage carbohydrate content. mRNA levels of genes involved in storage carbohydrate metabolism were also found reduced. Under N-limited conditions, the leu3D genotype elicited an amino-acid starvation response, leading to increased transcript levels of many amino acid biosynthesis genes. By combining the transcriptome data with data from earlier studies that measured DNA binding of Leu3p both in vitro and in vivo, BAT1, GAT1 and OAC1 were identified as additional Leu3p-regulated genes. This study demonstrates that unravelling of transcriptional regulation networks should preferably include several cultivation conditions and requires a combination of experimental approaches.
2007-07-07 | E-GEOD-2076 | biostudies-arrayexpress
Project description:Mice were put on either a control or low isoleucine diet and their liver transcriptomic expression was measured in both the fasting and fed state. This was to discover the impact of reducing a single branched chain amino acid on the metabolism of the liver.
2021-04-21 | GSE168588 | GEO
Project description:Transcriptional regulation of branched-chain amino acid metabolism in Saccharomyces cerevisiae involves two key regulator proteins, Leu3p and Gcn4p. Leu3p is a pathway-specific regulator, known to regulate six genes involved in branched-chain amino acid metabolism and one gene in nitrogen assimilation. Gcn4p is a global regulator, involved in the general response to amino acid and purine starvation. To investigate the contribution of Leu3p in regulation of gene expression, a leu3D strain was compared to an isogenic reference strain using DNA-microarray analysis. This comparison was performed for both glucose-grown, ammonium-limited and ethanol-limited, ammonium-excess chemostat cultures. In ethanol-limited cultures, absence of Leu3p led to reduced transcript levels of six of the seven established Leu3p target genes, but did not affect key physiological parameters. In ammonium-limited cultures, absence of Leu3p caused a drastic decrease in storage carbohydrate content. mRNA levels of genes involved in storage carbohydrate metabolism were also found reduced. Under N-limited conditions, the leu3D genotype elicited an amino-acid starvation response, leading to increased transcript levels of many amino acid biosynthesis genes. By combining the transcriptome data with data from earlier studies that measured DNA binding of Leu3p both in vitro and in vivo, BAT1, GAT1 and OAC1 were identified as additional Leu3p-regulated genes. This study demonstrates that unravelling of transcriptional regulation networks should preferably include several cultivation conditions and requires a combination of experimental approaches. Keywords: ordered
2004-12-17 | GSE2076 | GEO
Project description:The aim of this study was to determine how nitrogen repletion affected the genomic cell response of a Saccharomyces cerevisiae wine yeast strain, in particular within the first hour following relief from nutrient starvation. We found almost 4000 genes induced or repressed sometimes within minutes of nutrient changes. Some of the transcriptional responses to nitrogen depended on the TOR pathway which control positively ribosomal protein genes, amino acid and purine biosynthesis or amino acid permease genes and negatively stress-response genes, RTG specific TCA cycle genes and NCR sensitive genes. Some unexpected transcriptional responses concerned all the glycolytic genes, the starch and glucose metabolism and citrate cycle related genes which were down-regulated, as well as genes from the lipid metabolism.
2018-07-10 | GSE116766 | GEO
Project description:Two nutrient sensing and regulatory pathways, the general amino acid control (GAAC) and the target of rapamycin (TOR), control yeast growth and metabolism in response to changes in nutrient availability. Starvation for amino acids activates the GAAC pathway, involving Gcn2p phosphorylation of eIF2 and preferential translation of GCN4, a transcription activator of genes involved in amino acid metabolism. TOR senses nitrogen availability and regulates gene expression through transcription factors, such as Gln3p. We used microarray analyses to address the integration of the GAAC and TOR pathways in directing the yeast transcriptome in response to amino acid starvation and rapamycin treatment. Of the ~2500 genes whose expression was changed by 2-fold or greater, Gcn4p and Gln3p were required for 542 and 657 genes, respectively. While Gcn4p activates a common core of 57 genes in response to amino acid starvation or rapamycin treatment, the different stress arrangements allow for variations in Gcn4p-directed transcription. With few exceptions, genes requiring Gcn2p eIF2 kinase for induced expression also required Gcn4p, emphasizing the role of Gcn2p as an upstream activator of Gcn4p-directed transcription. There is also significant coordination between the GAAC and TOR pathways, with Gcn4p being required for activation of more genes during rapamycin treatment than Gln3p. Importantly, TOR regulates the GAAC-directed transcription of genes required for assimilation of nitrogen sources, such as γ-amino-butyric acid. Therefore, yeast has integrated gene expression responses to amino acid abundance and nitrogen source quality through the control of Gcn2p phosphorylation of eIF2 and GCN4 translation. Keywords: gene expression In this study, we carried out microarray analyses in a collection of yeast strains deleted for GCN2, GCN4, and GLN3, individually or in combinations, to explore the importance of the TOR and GAAC pathways in directing the transcriptome in response to amino acid starvation and rapamycin treatment.
2010-03-07 | E-GEOD-15254 | biostudies-arrayexpress
Project description:Transcriptional control of amino acid biosynthesis
| PRJNA100395 | ENA
Project description:Iron is an essential cofactor for a wide range of cellular processes. Previous studies have shown that siderophore-mediated uptake and intracellular handling of iron are crucial for virulence of Aspergillus fumigatus. Here we show that the bzip-type transcription factor HapX plays a crucial role in the transcriptional remodeling required for adaption to iron starvation in this opportunistic fungal pathogen. HapX was found to be interconnected in a negative feed-back loop with the previously identified iron regulator SreA: SreA repressed expression of hapX during iron sufficiency and HapX repressed sreA during iron starvation. Genome-wide transcriptional profiling and analysis of selected metabolites (protophorphyrine IX, siderophores and amino acids) indicated extensive metabolic remodeling in response to iron starvation. HapX was found to participate in both, repression and activation of genes during iron starvation. HapX was in particular required for repression of iron-dependent and mitochondrial-localized activities including respiration, TCA cycle, amino acid metabolism, iron-sulfur-cluster biosynthesis and heme biosynthesis. Pathways positively affected by HapX included production of siderophores and the ribotoxin and major allergen AspF1. Analysis of the free amino acid pool revealed HapX-dependent coordination of the production of siderophores with the supply of its precursor ornithine. Consistent with the hapX expression pattern, HapX-deficiency was deleterious with respect to growth rate and conidiation during iron depleted but not iron-replete conditions. HapX-deficiency caused significant attenuation of virulence in a murine model aspergillosis underlining that A. fumigatus faces iron starvation in the host and that the HapX-dependent metabolic reprogramming is therefore crucial for virulence.
2010-07-01 | GSE22052 | GEO