Project description:The effects of RyhB expression were examined by Ribo-seq and RNA-seq after 10 min to avoid indirect effects. Expression of RyhB was induced by arabinose from cells carrying pBAD-ryhB plasmid. The RyhB expression was confirmed by real-time PCR. As a control, cells with vector pNM12 were grown and induced. The cells were pulverized and total mRNAs were extracted from the pulverized cells and processed for Ribo-seq and RNA-seq.
Project description:A quantitative view of cellular functions requires precise measures of the rates of biomolecule production, especially proteins-the direct effectors of biological processes. Here we present a genome-wide approach, based on ribosome profiling, for measuring absolute protein synthesis rates. The resultant E. coli dataset transforms our understanding of the extent to which protein synthesis is precisely controlled to optimize function and efficiency. For example, members of multi-protein complexes are made in precise proportion to their stoichiometry, whereas components of functional modules are produced differentially according to their hierarchical role. Estimates of absolute protein abundance also reveal principles used to optimize design. These include how the level of different types of transcription factors is optimized for rapid response, and how a metabolic pathway (methionine biosynthesis) balances production cost with activity requirements. More broadly, our studies reveal how general principles, important both for understanding natural systems and for synthesizing new ones, emerge from global quantitative analyses of protein synthesis. 4 samples of E. coli ribosome profiling and mRNA-seq, including biological replicates
Project description:In enteric bacteria, the transcription factor ?E maintains membrane homeostasis by inducing expression of proteins involved in membrane repair and of two small, regulatory RNAs (sRNAs) that downregulate synthesis of abundant membrane porins. Here, we describe the discovery of a third ?E-dependent sRNA, MicL, transcribed from a promoter located within the coding sequence of the cutC gene. MicL is synthesized as a 308 nt primary transcript that is processed to an 80 nt form. Both forms possess features typical of Hfq-binding sRNAs, but surprisingly only target a single mRNA, which encodes the outer membrane lipoprotein Lpp, the most abundant protein of the cell. We show that the copper sensitivity phenotype previously ascribed to inactivation of the cutC gene is actually derived from the loss of MicL and elevated Lpp levels. This observation raises the possibility that other phenotypes currently attributed to protein defects are due to deficiencies in unappreciated regulatory RNAs. We also report that ?E activity is sensitive to Lpp abundance and that MicL and Lpp comprise a new ?E regulatory loop that opposes membrane stress. Together MicA, RybB and MicL allow ?E to repress the expression of all abundant outer membrane proteins in response to stress. 12 samples mRNA-seq data, 2 samples ribosome profiling data. For mRNA-seq data, samples were gathered at the indicated time (in min) after induction of either vector (WT), long (MicL), and short (MicL-S) forms of MicL.
Project description:Caulobacter crescentus undergoes an asymmetric cell division controlled by a genetic circuit that cycles in space and time. We provide a universal strategy for defining the coding potential of bacterial genomes by applying ribosome profiling, RNA-seq, global 5’-RACE, and liquid chromatography coupled with tandem mass spectrometry (LC-MS) data to the 4-megabase C. crescentus genome. We mapped transcript units at single base-pair resolution using RNA-seq together with global 5’ RACE. Additionally, using ribosome profiling and LC-MS, we mapped translation start sites and coding regions with near complete coverage. We found most start codons lacked corresponding Shine-Dalgarno sites although ribosomes were observed to pause at internal Shine-Dalgarno sites within the ORF. These data suggest a more prevalent use of the Shine-Dalgarno sequence for ribosome pausing rather than translation initiation in C. crescentus. Overall 19% of the transcribed and translated genomic elements were newly identified or significantly improved by this approach providing a valuable genomic resource to elucidate the complete C. crescentus genetic circuitry that controls asymmetric cell division. Ribosome profiling and RNA-seq data were collected in Caulobacter crescentus NA1000 cells grown in M2G and PYE media to map transcript and ORF features in the genome.
Project description:Protein synthesis by ribosomes takes place on a linear substrate but at variable speeds. Transient pausing of ribosomes can impact a variety of co-translational processes, including protein targeting and folding. These pauses are influenced by the sequence of the mRNA. Thus redundancy in the genetic code allows the same protein to be translated at different rates. However, our knowledge of both the position and the mechanism of translational pausing in vivo is highly limited. Here we present a genome-wide analysis of translational pausing in bacteria using ribosome profiling-deep sequencing of ribosome-protected mRNA fragments. This approach enables high-resolution measurement of ribosome density profiles along most transcripts at unperturbed, endogenous expression levels. Unexpectedly, we found that codons decoded by rare tRNAs do not lead to slow translation under nutrient-rich conditions. Instead, Shine-Dalgarno-(SD) like features within coding sequences cause pervasive translational pausing. Using an orthogonal ribosome possessing an altered anti-SD sequence, we demonstrated that pausing is due to hybridization between mRNA and the 16S rRNA of the translating ribosome. In protein coding sequences, internal SD sequences are disfavoured, which leads to biased usage, avoiding codons and codon pairs that resemble canonical SD sites. Our results indicate that internal SD-like sequences are a major determinant of translation rates and a global driving force for the coding of bacterial genomes. Identification of translation pause sites in vivo using ribosome profiling
Project description:Mammalian transcriptomes display complex circadian rhythms with multiple phases of gene expression that cannot be accounted for by current models of the molecular clock.M-BM- We have determined the underlyingM-BM- mechanisms by measuring nascent RNA transcription around the clock in mouse liver. Unbiased examination of eRNAs that cluster in specific circadian phasesM-BM- identified functional enhancers driven by distinct transcription factors (TFs). We further identify on a global scale the components of the TF cistromes that function to orchestrate circadian gene expression. Integrated genomicM-BM- analysesM-BM- also revealed novel mechanisms by which a single circadian factor controls opposing transcriptional phases. These findings shed new light on the diversity and specificity of TF function in the generation of multiple phases of circadian gene transcription in a mammalian organ. Nascent RNA transcripts in mouse liver were profiled at 8 time points of the 24 hour light-dark cycle. Static state mRNAs in WT and Rev-erbA -/- mice were profiled using microarray (GSE59460).
Project description:During translation elongation, the ribosome ratchets along its mRNA template, incorporating each new amino acid and translocating from one codon to the next. The elongation cycle requires dramatic structural rearrangements of the ribosome. We show here that deep sequencing of ribosome-protected mRNA fragments reveals not only the position of each ribosome but also, unexpectedly, its particular stage of the elongation cycle. Sequencing reveals two distinct populations of ribosome footprints, 28-30 nucleotides and 20-22 nucleotides long, representing translating ribosomes in distinct states, differentially stabilized by specific elongation inhibitors. We find that the balance of small and large footprints varies by codon and is correlated with translation speed. The ability to visualize conformational changes in the ribosome during elongation, at single-codon resolution, provides a new way to study the detailed kinetics of translation and a new probe with which to identify the factors that affect each step in the elongation cycle. Ribosome profiling, or sequencing of ribosome-protected mRNA fragments, in yeast. We assay ribosome footprint sizes and positions in three conditions: untreated yeast (3 replicates) and yeast treated with translation inhibitors cycloheximide (2 replicates) and anisomycin (2 biological replicates, one technical replicate). We also treat yeast with 3-aminotriazole to measure the effect of limited histidine tRNAs on ribosome footprint size and distribution (two treatment durations).
Project description:Hfq is a transcriptional and translational pleiotropic regulator in several bacteria. RNA-Seq, Ribo-Seq and Proteomic analyses were carried out in the wild-type and a hfq deletion strain of Pseudomonas fluorescens SBW25 with the intention to separate the influence of Hfq on the transcript stability and translation. This submission relates to the Ribosome profiling data only. Ribosomes were purified from MNase treated cell lysates by density gradient ultracentrifugation from two replicate cultures each of SBW25-WT and SBW25-hfq strains. RNA was extracted from the purified ribosomes and subjected to RNA-Seq in an Illumina HiSeq2000 machine. The resulting sequence data was analysed by mapping to the reference sequence of Pseudomonas fluorescens SBW25 as available in the Genbank accession NC_012660.
Project description:Ribosome profiling performed in Mycobacterium smegmatis MC2 155 wild-type cells versus cells with deletions of genes encoding small ORFs MSMEG_0945 and MSMEG_1916.
Project description:Hox genes are essential regulators of embryonic development. They are activated in a temporal sequence following their topological order within their genomic clusters. Subsequently, states of activity are fine-tuned and maintained to translate into domains of progressively overlapping gene products. While the mechanisms underlying such temporal and spatial progressions begin to be understood, many of their aspects remain unclear. We have systematically analyzed the 3D chromatin organization of Hox clusters in vivo, during their activation using high-resolution circular chromosome conformation capture (4C-seq). Initially, Hox clusters are organized as single 3D chromatin compartments decorated with bivalent chromatin marks. Their progressive transcriptional activation is associated with a dynamic bi-modal 3D organization, whereby the genes switch one after the other, from an inactive to an active 3D compartment. These local 3D dynamics occur within a larger constitutive framework of interactions within the surrounding Topological Associated Domains, which confirms previous results that regulation of this process in primarily cluster intrinsic. The local step-wise progression in time can be stopped and memorized at various body levels and hence it may accounts for the various chromatin architectures previously described at different anterior to posterior body levels for the same embryo at a later stage. Circular Chromosome Conformation Capture (4C-seq) samples from mouse ES cells and mouse embryonic samples at different stages of development. Data based on 41 biological samples.