Project description:We investigated the effect that intragenic s54 binding sites have on transcripton elongation. In an rpoN deletion we have over-expressed rpoN from a plasmid (with vector only contol) and then looked at changes in transcription elongation around intragenic s54 binding sites by RNA-seq. We are also looking at changes in transcription initiation/elongation at sites of sigma factor overlap.
Project description:Bacteria can generate heterogeneity through phase variation, including enzyme-mediated inversion of specific intergenic regions of genomic DNA. We developed a computation tool that identifies invertible elements using long-read datasets, PhaVa. We identified over 300 ‘intragenic invertons,’ a new class of invertible elements entirely within genes, in both bacteria and archaea. In the gut commensal Bacteroides thetaiotaomicron, we experimentally characterized an intragenic inverton in the thiamine biosynthesis protein thiC. We used mass spectrometry in data-independent acquisition mode to identify and quantify B. theta proteins, including thiC inverton expression at the protein level.
Project description:The transcription termination factor Rho is a global regulator of RNA polymerase (RNAP). Although individual Rho-dependent terminators have been studied extensively, less is known about the sites of RNAP regulation by Rho on a genome-wide scale. Using chromatin immunoprecipitation and microarrays (ChIP-chip), we examined changes in the distribution of Escherichia coli RNAP in response to the Rho-specific inhibitor bicyclomycin (BCM). We found ~200 Rho-terminated loci that were divided evenly into two classes: intergenic (at the ends of genes) and intragenic (within genes). The intergenic class contained noncoding RNAs such as small RNAs (sRNAs) and transfer RNAs (tRNAs), establishing a previously unappreciated role of Rho in termination of stable RNA synthesis. The intragenic class of terminators included a novel set of short antisense transcripts, as judged by a shift in the distribution of RNAP in BCM-treated cells that was opposite to the direction of the corresponding gene. These Rho-terminated antisense transcripts point to a novel role of noncoding transcription in E. coli gene regulation that may resemble the ubiquitous noncoding transcription recently found to play myriad roles in eukaryotic gene regulation.
Project description:The transcription termination factor Rho is a global regulator of RNA polymerase (RNAP). Although individual Rho-dependent terminators have been studied extensively, less is known about the sites of RNAP regulation by Rho on a genome-wide scale. Using chromatin immunoprecipitation and microarrays (ChIP-chip), we examined changes in the distribution of Escherichia coli RNAP in response to the Rho-specific inhibitor bicyclomycin (BCM). We found ~200 Rho-terminated loci that were divided evenly into two classes: intergenic (at the ends of genes) and intragenic (within genes). The intergenic class contained noncoding RNAs such as small RNAs (sRNAs) and transfer RNAs (tRNAs), establishing a previously unappreciated role of Rho in termination of stable RNA synthesis. The intragenic class of terminators included a novel set of short antisense transcripts, as judged by a shift in the distribution of RNAP in BCM-treated cells that was opposite to the direction of the corresponding gene. These Rho-terminated antisense transcripts point to a novel role of noncoding transcription in E. coli gene regulation that may resemble the ubiquitous noncoding transcription recently found to play myriad roles in eukaryotic gene regulation. Chromatin immunoprecipitation (ChIP) experiments were performed using antibodies against RNA polymerase (Beta or Beta' subunit) in cells treated with 20ug/ml bicyclomycin or untreated cells. Differentially labeled ChIP DNA and genomic DNA were competitively hybridized to an E. coli K-12 MG1655 tiling array with overlapping probes at ~12bp spacing across the entire genome. The series contains 4 datasets.