Effect of LacI (lac repressor) on transcription in Salmonella
Ontology highlight
ABSTRACT:
ORGANISM(S): Salmonella enterica subsp. enterica serovar Typhimurium str. LT2
PROVIDER: GSE15950 | GEO | 2009/05/07
SECONDARY ACCESSION(S): PRJNA115353
REPOSITORIES: GEO
Similar Datasets
Project description:Salmonella is an important enteric pathogen that causes a spectrum of diseases varying from mild gastroenteritis to life threatening typhoid fever. Salmonella does not have lac operon. However, E. Coli, Salmonellaâs close relative, has lac operon. Being an enteric pathogen like E. coli, Salmonella will also benefit from lac operon. Then, why Salmonella has lost lac operon?. To address this question, lacI, an important component of lac operon was expressed in Salmonella via pTrc99A plasmid. As a control, pTrc99A without lacI was also expressed in Salmonella. The effect of LacI on the transcription profile of Salmonella was analyzed using microarray technique. Overall design The total RNA was isolated from Salmonella using âRNeasy Mini Kitâ (QIAGEN). Organism used: Salmonella enterica serovar Typhimurium LT2 * Slides: Agilentâs arrays (8x15k) AMADID: NO: 17809 * Starting material: Salmonella RNA in nuclease-free water * RNA Samples used: Wild type (WT), WT + pTrc99A+LacI (PTRC), WT + pTrc99A-LacI(Delta lac) * Labeling kit: MessageAmp⢠II-Bacteria RNA Amplification Kit from Ambion Cat # AM1790 * Labeling Method: T7 promoter based-linear amplification to generate labeled complementary RNA * Total RNA and cRNA Purification Kit: Qiagenâs RNeasy minikit Cat#74104 * Hybridization Kit: Agilentâs In situ Hybridzation kit 5184-3568 * RNA quality was checked using Bioanalyzer. The array slides were scanned immediately by PerkinElmer Scan array Gx Microarray scanner. The Scan array software (PerkinElmer) was used for grid wise normalization of array images. Two arrays were used with mutant and rescue experiments and dye swap experiments were included in the final analysis. The data was analysed by GeneSpring GX and Biointerpreter software from Genotypic Technology, Bangalore. The differential expression was considered if the Log 2 mean of at least -1 for the down regulated genes and +1 for the upregulated genes. We considered only the genes that were reproducible from both replicates.
2010-05-19 | E-GEOD-15950 | biostudies-arrayexpress
Project description:We analyze LacI mutations with the goal to understand and better predict basal transcriptional repression function after mutation. This study utilized lac repressor variants from the Taylor, et al. 2015 Nature Methods study including ten tiles of synthesized single mutations (NCBI GEO Series GSE75009), and an additional six tiles corresponding to higher-order mutations (this study).
2021-06-22 | GSE175456 | GEO
Project description:Examination of intestinal colonization of enteric pathogen Salmonella typhimurium
2015-08-14 | MSV000079240 | MassIVE
Project description:In this work we introduce a new high-throughput method, Spec-seq, that directly measures specificity by sequencing. It has several advantages over existing methods to quantify large collections (thousands) of binding site energies in one experiment. Using lac repressor as an example, we show that this method has excellent reproducibility giving energy measurements generally consistent within about 0.1kT. While not measuring in parallel as many different sequences as some of the higher throughput methods, we obtain high accuracies because we measure exactly what is necessary, the relative affinity to a large collection of sequences, without any mathematical fitting procedures or approximations required. It is similar to MITOMI in the number of different sites that can be analyzed in parallel, but it is much simpler to perform, requiring only a means to separate bound and unbound fractions which are then sequenced using standard high throughput, short read sequencing machines that are now readily available. When applied to the lac repressor we obtain, in a single experiment, data covering a large fraction of all the previous studies, plus thousands of additional variants, allowing us to compile a much more comprehensive profile of its specificity. We learn that the lac repressor can bind to sites of different lengths but that the preferred sequence, and the mode of binding, depends on the length. We also apply the method to two other members of the LacI/GalR protein family, PurR and YcjW, to obtain extensive models of their specificity and test the generality of the lac repressor's ability to bind to operators of variable length. We find that the lac repressor is apparently unique in its ability to bind with high affinity to sites of different lengths and with different modes of binding.
2014-10-01 | GSE61223 | GEO
Project description:In this work we introduce a new high-throughput method, Spec-seq, that directly measures specificity by sequencing. It has several advantages over existing methods to quantify large collections (thousands) of binding site energies in one experiment. Using lac repressor as an example, we show that this method has excellent reproducibility giving energy measurements generally consistent within about 0.1kT. While not measuring in parallel as many different sequences as some of the higher throughput methods, we obtain high accuracies because we measure exactly what is necessary, the relative affinity to a large collection of sequences, without any mathematical fitting procedures or approximations required. It is similar to MITOMI in the number of different sites that can be analyzed in parallel, but it is much simpler to perform, requiring only a means to separate bound and unbound fractions which are then sequenced using standard high throughput, short read sequencing machines that are now readily available. When applied to the lac repressor we obtain, in a single experiment, data covering a large fraction of all the previous studies, plus thousands of additional variants, allowing us to compile a much more comprehensive profile of its specificity. We learn that the lac repressor can bind to sites of different lengths but that the preferred sequence, and the mode of binding, depends on the length. We also apply the method to two other members of the LacI/GalR protein family, PurR and YcjW, to obtain extensive models of their specificity and test the generality of the lac repressor's ability to bind to operators of variable length. We find that the lac repressor is apparently unique in its ability to bind with high affinity to sites of different lengths and with different modes of binding. 4 independent experiments.
2014-10-01 | E-GEOD-61223 | biostudies-arrayexpress
Project description:Disease outbreaks due to the consumption of legume seedlings contaminated with human enteric bacterial pathogens like Escherichia coli O157:H7 and Salmonella enterica are reported every year. We found surface and internal colonization of Medicago truncatula by Salmonella enterica and Escherichia coli O157:H7 even with inoculum levels as low as two bacteria per plant. Expression analyses using microarray revealed that some Medicago truncatula genes were regulated in a similar manner in response to both of these enteric pathogens. Medicago truncatula roots were inoculated with low inoculum levels of two enteric bacteria per plant (E. coli O157:H7 and Salmonella). 10 days post inoculated plants were used for RNA extraction and hybridization on Affymetrix microarrays.
2013-12-18 | E-GEOD-53406 | biostudies-arrayexpress
Project description:AbuOun2009 - Genome-scale metabolic network
of Salmonella typhimurium (iMA945)
This model is described in the article:
Genome scale reconstruction
of a Salmonella metabolic model: comparison of similarity and
differences with a commensal Escherichia coli strain.
AbuOun M, Suthers PF, Jones GI,
Carter BR, Saunders MP, Maranas CD, Woodward MJ, Anjum MF.
J. Biol. Chem. 2009 Oct; 284(43):
29480-29488
Abstract:
Salmonella are closely related to commensal Escherichia coli
but have gained virulence factors enabling them to behave as
enteric pathogens. Less well studied are the similarities and
differences that exist between the metabolic properties of
these organisms that may contribute toward niche adaptation of
Salmonella pathogens. To address this, we have constructed a
genome scale Salmonella metabolic model (iMA945). The model
comprises 945 open reading frames or genes, 1964 reactions, and
1036 metabolites. There was significant overlap with genes
present in E. coli MG1655 model iAF1260. In silico growth
predictions were simulated using the model on different carbon,
nitrogen, phosphorous, and sulfur sources. These were compared
with substrate utilization data gathered from high throughput
phenotyping microarrays revealing good agreement. Of the
compounds tested, the majority were utilizable by both
Salmonella and E. coli. Nevertheless a number of differences
were identified both between Salmonella and E. coli and also
within the Salmonella strains included. These differences
provide valuable insight into differences between a commensal
and a closely related pathogen and within different pathogenic
strains opening new avenues for future explorations.
This model is hosted on
BioModels Database
and identified by:
MODEL1507180009.
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To the extent possible under law, all copyright and related or
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2015-07-30 | MODEL1507180009 | BioModels
Project description:Transcriptome comparison of the Streptococcus pneumoniae strain D39 grown in the presence of either lactose or galactose with that of the strain grown in the presence of glucose, revealed the elevated expression of various genes and operons, including the lac gene cluster that is organized into two operons i.e. lac operon-I (lacABCD) and lac operon-II (lacTFEG). Deletion of the DeoR family transcriptional regulator lacR that is present downstream of the lac gene cluster, revealed elevated expression of lac operon-I, even in the absence of lactose. This suggests a function of LacR as a transcriptional repressor of lac operon-I that encodes enzymes involved in the Tagatose-6-P pathway in the absence of lactose or galactose. Deletion of lacR did not affect the expression of lac operon-II that encodes for a lactose-specific PTS. This finding was further confirmed by ?-galactosidase assays with PlacA-lacZ and PlacT-lacZ in the presence of either lactose or glucose as a sole carbon source in the medium. This suggests the presence of another transcriptional regulator in the regulation of lac operon-II, which could be the BglG-family transcriptional antiterminator LacT. We demonstrate the role of LacT as a transcriptional activator of lac operon-II in the presence of lactose and CcpA-independent regulation of the lac gene cluster in S. pneumoniae. This SuperSeries is composed of the SubSeries listed below.
2014-06-20 | GSE58184 | GEO
Project description:Effect of LacI (lac repressor) on transcription in Salmonella
| PRJNA115353 | ENA
Project description:Disease outbreaks due to the consumption of legume seedlings contaminated with human enteric bacterial pathogens like Escherichia coli O157:H7 and Salmonella enterica are reported every year. We found surface and internal colonization of Medicago truncatula by Salmonella enterica and Escherichia coli O157:H7 even with inoculum levels as low as two bacteria per plant. Expression analyses using microarray revealed that some Medicago truncatula genes were regulated in a similar manner in response to both of these enteric pathogens.
2013-12-18 | GSE53406 | GEO