Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Effect of LacI (lac repressor) on transcription in Salmonella

ABSTRACT: 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: MessageAmpâ¢ 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.

ORGANISM(S): Salmonella enterica subsp. enterica serovar Typhimurium str. LT2

SUBMITTER: DrSandeepa M E

PROVIDER: E-GEOD-15950 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:DNA-binding anticancer agents cause alteration in chromatin structure and dynamics. Here, we report the dynamic interaction of the DNA intercalator and potential anticancer, plant alkaloid, sanguinarine (SGR) with chromatin. Association of SGR with different levels of chromatin structure was found to be enthalpy driven. Apart from DNA, it binds with comparable affinity to histones and induces chromatin aggregation. The dual binding property of SGR leads to inhibition of core histone modifications. Although it potently inhibits H3K9 methylation by G9a in vitro, H3K4 and H3R17 methylation are more profoundly inhibited in cells. SGR inhibits histone acetylation both in vitro and in vivo. It does not affect the in vitro transcription from DNA template but significantly represses acetylation-dependent chromatin transcription. SGR mediated repression of epigenetic marks and the alteration of chromatin geography also result in modulation of global gene expression. These data conclusively show that the anticancer DNA-binding intercalator as a modulator of chromatin modifications and transcription in the chromatin context. The total RNA was isolated from control and treated cells using the TRIzol (Invitrogen) method. The Micromax direct labeling kit, MPS502 (PerkinElmer), was used to synthesize the labeled cDNA from 70 ug of total RNA and further process the hybridized cDNA on the array. All the steps were carried out according to manufacturer’s instructions (www.perkinelmer.com/lifesciences). The array slides were scanned immediately by the PerkinElmer Scan array Gx Microarray scanner. The Scan array software (PerkinElmer) was used for grid wise normalization of array images. Five arrays were used with at least two biological treatments of cells, 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 downregulated genes and +1 for the upregulated genes. We considered only the genes that were reproducible from all five replicates.

Project description:DNA binding anticancer agents cause alteration in chromatin structure and dynamics. Here, we report the dynamic interaction of the DNA intercalator and potential anticancer, plant alkaloid, Sanguinarine (SGR) with chromatin. Association of SGR with different levels of chromatin structure was found to be enthalpydriven. Apart from DNA it binds with comparable affinity to histones and induces chromatin aggregation. The dual binding property of SGR leads to inhibition of core histone modifications. Although, it potently inhibits H3K9 methylation by G9a in vitro, H3K4 and H3R17 methylation are more profoundly inhibited in cells. SGR inhibits histone acetylation both in vitro and in vivo. It does not affect the in vitro transcription from DNA template but significantly represses acetylation dependent chromatin transcription. SGR mediated repression of epigenetic marks and the alteration of chromatin geography, also result in modulation of global gene expression. These data conclusively, show the anticancer DNA binding intercalator as a modulator of chromatin modifications and transcription in the chromatin context. The total RNA was isolated from control and treated cells using TRIZOL (Invitrogen) method. The Micromax direct labeling kit, MPS502 (PerkinElmer) was used to synthesize the labeled cDNA from 70 ug of total RNA and further process the hybridized cDNA on the array. All the steps were carried out according to manufacturerâs instructions (www.perkinelmer.com/lifesciences). 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 at least one biological treatment of cells and dye swap experiment 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.

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Effect of LacI (lac repressor) on transcription in Salmonella

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