Genome conformation capture reveals that the Escherichia coli chromosome is organized by replication and transcription
ABSTRACT: To fit within the confines of the cell, bacterial chromosomes are highly condensed into a structure called the nucleoid. Despite the high degree of compaction in the nucleoid, the genome remains accessible to essential biological processes, such as replication and transcription. Here, we present the first high-resolution chromosome conformation capture-based molecular analysis of the spatial organization of the Escherichia coli nucleoid during rapid growth in rich medium and following an induced amino acid starvation that promotes the stringent response. Our analyses identify the presence of origin and terminus domains in exponentially growing cells. Moreover, we observe an increased number of interactions within the origin domain and significant clustering of SeqA-binding sequences, suggesting a role for SeqA in clustering of newly replicated chromosomes. By contrast, ‘histone-like’ protein (i.e. Fis, IHF and H-NS) binding sites did not cluster, and their role in global nucleoid organization does not manifest through the mediation of chromosomal contacts. Finally, genes that were downregulated after induction of the stringent response were spatially clustered, indicating that transcription in E. coli occurs at transcription foci. A 4 chips study of exponentially growing wild type E. coli strain MG1655 grown in LB rich media or after induction of the stringent response by serine hydroxamate for 30 min. Two technical replicates, Three biological replicates mixed prior hybridization on the chip.
Project description:Investigation of whole genome gene expression level changes in a Escherichia coli MG1655 K-12 nsrR with AUG start codon compared to the wild type nsrR (with a GUG start codon) and to the control lacking the nsrR gene. Conversion of the nsrR start codon from the wild type GUG to AUG increased the efficiency of translation and had measurable effects on the expression patterns of some NsrR regulated genes. A nine chip study using total RNA recovered from three separate cultures of Escherichia coli MG1655 K-12 AUGnsrR, three separate cultures of the WT nsrR (GUGnsrR) and three separate cultures of nsrR deletion strain. Each chip measures the expression level of 4,254 genes from Escherichia coli MG1655 K-12 with eight 60-mer probes per gene, with 2-fold technical redundancy.
Project description:Investigation of whole genome gene expression level in E. coli rpoS knock-out strain grown up to stationary phase in M9 minimal media supplemented with 0.2% glucose E. coli rpoS deletion mutant grown up to OD600nm 1.5 (stationary phase) in M9 minimal media supplemented with 0.2% glucose. The high-density oligonucleotide tiling arrays used were consisted of 371,034 oligonucleotide. Data for wild type controls are GSM389302, GSM389303, and GSM389304.
Project description:Investigation of whole genome gene expression level in E. coli K-12 MG1655 in glucose M9 minimal media with/without heatshock A six chip study using total RNA recovered from E. coli K-12 MG1655 grown up to OD600nm 0.6 (mid-exponential phase) in M9 minimal media supplemented with 0.2% glucose with/without heatshock in 42oC. The high-density oligonucleotide tiling arrays used were consisted of 371,034 oligonucleotide probes with 50-bp length that are spaced 25 bp apart across the E. coli genome (NimbleGen). Experiments were performed with three biological replicates.
Project description:Investigation of the whole genome expression level changes in phosphate limited Bacillus subtilis wild-type and delta-phoPR cells Investigation of the whole genome expression level changes of wild-type and delta-phoPR Bacills subtilis cells comparing high and low phosphate medium For each sample analyzed in this study 3 technical replicates were performed. 3 different samples were taken for wild-type cell and delta-phoPR cell, respectively. Samples were taken from exponentially growing cells in high and low phosphate medium as well as from phosphate-limited cells.
Project description:Examination of E. coli transcripts present in bacteria in urine samples from 8 patients attending a urology clinic with symptoms of cystitis, as compared to transcripts present in the same E. coli strains during mid-exponential growth in filter-sterilized human urine in vitro. A 48 array study using total RNA recovered from eight clinical E. coli isolates immediately following collection from women and following culture in pooled human urine ex vivo. Each array measures the expression of the 5,379 ORFs in the CFT073 genome, using an average of 14 60-mer probes per ORF. Arrays were performed in triplicate: biological replicates of the in vitro-cultured samples and technical replicates of the in vivo samples.
Project description:Investigation on expression levels of normal tissue from prostate cancer patients on locus 8q24. 3 chips with 3 arrays each study, using 3 pairs of normal vs. tumor tissue and 3 replicates of the same sample. Each chip contained one pair of normal vs. tumor and one copy of the repeated sample.
Project description:Investigation on expression levels of normal tissue from prostate cancer patients on locus 8q24. The region chr8:127640000-129120000 is tiled with 60 nt probes at 10 nt interval (hg18) 7 chip study, using 7 independent samples.
Project description:Investigation on expression levels of normal tissue from prostate cancer patients on locus 8q24. The region chr8:127640000-129120000 is tiled with isothermal probes (hg17) 7 chip study, using 7 independent samples.
Project description:Embryonic stem cells (ESCs) and induced-pluripotent stem cells (iPSCs) self-renew and differentiate into an array of cell types in vitro and in vivo. A complex network of genetic and epigenetic pathways regulates the self-renewal and differentiation of these pluripotent cells, and the structure and covalent modifications of chromatin play a prominent role in this process. We examine nucleosome occupancy in mouse and human embryonic stem cells (ESCs), induced-pluripotent stem cells (iPSCs), and differentiated cell types using MNase-seq. To address variability inherent in this technique, we developed a bioinformatic approach that enabled the identification of regions of difference (RoD) in nucleosome occupancy between pluripotent and somatic cells. The majority of changes in nucleosomal signatures that occur in differentiation are reset during reprogramming. We conclude that changes in nucleosome occupancy are a hallmark of pluripotency and likely identify key regulatory regions that play a role in determining cell identity. A six chip study using total RNA recovered from three cell types with 2 replicates each