Project description:Anti-sense non-coding transcripts, genes-within-genes, and convergent gene pairs are prevalent among eukaryotes. The existence of such transcription units raises the question of what happens when RNA polymerase II (RNAPII) molecules collide head-to-head. Here we use a combination of biochemical and genetic approaches in yeast to show that polymerases transcribing opposite DNA strands cannot bypass each other. RNAPII stops, but does not dissociate upon head-to-head collision in vitro, suggesting that opposing polymerases represent insurmountable obstacles for each other. Head-to-head collision in vivo results in RNAPII stopping as well, and removal of collided RNAPII from the DNA template can be achieved via ubiquitylation-directed proteolysis. Indeed, in cells lacking efficient RNAPII poly-ubiquitylation, the half-life of collided polymerases increases, so that these can be detected between convergent genes by ChIP-Seq. These results provide new insight into fundamental mechanisms of gene traffic control, and point to an unexplored effect of anti-sense transcription on gene regulation via polymerase collision. ChIP-Seq of RNA polymerase II was performed with WT and Elongain C deletion mutant (elc1M-bM-^HM-^F) cells. 4H8 antibody against the Rpb1 C-terminal domain was used for RNA polymerase II immunoprecipitation, whilst mouse IgG antibody was used for control immunoprecipitations. Two biological replicates were performed for both WT and elc1M-bM-^HM-^F.
Project description:Anti-sense non-coding transcripts, genes-within-genes, and convergent gene pairs are prevalent among eukaryotes. The existence of such transcription units raises the question of what happens when RNA polymerase II (RNAPII) molecules collide head-to-head. Here we use a combination of biochemical and genetic approaches in yeast to show that polymerases transcribing opposite DNA strands cannot bypass each other. RNAPII stops, but does not dissociate upon head-to-head collision in vitro, suggesting that opposing polymerases represent insurmountable obstacles for each other. Head-to-head collision in vivo results in RNAPII stopping as well, and removal of collided RNAPII from the DNA template can be achieved via ubiquitylation-directed proteolysis. Indeed, in cells lacking efficient RNAPII poly-ubiquitylation, the half-life of collided polymerases increases, so that these can be detected between convergent genes by ChIP-Seq. These results provide new insight into fundamental mechanisms of gene traffic control, and point to an unexplored effect of anti-sense transcription on gene regulation via polymerase collision. Total RNA was extracted from WT or Elongin C deletion mutant (elc1M-bM-^HM-^F) cells and strand-specific RNA-Seq was performed. Three biological replicates were performed for WT and elc1M-bM-^HM-^F.
Project description:The production of Tobacco Acid Pyrophosphatase (TAP), an enzyme commonly used for the removal of the 5â??cap of eukaryotic mRNAs, has been recently discontinued. Here we performed a comparison of current alternatives for the mapping of 5â??cap mRNAs and the associated transcription start sites in Sacharomyces cerevisiae. Specifically we compared TAP with Cap-clip and a Decapping Pyrophosphohydrolase. Our results suggest that Cap-clip is a good alternative for TAP. We used two biological replicates of S. cerevisiae that was grown to exponential phase (OD600 ~1) in rich media (YPAD). Samples where processed until the dephosphorylation step (CIP treatment). After that each sample was split in 4 aliquots: TAP treatment, Cap-Clip treatment, Decapping Pyrophosphohydrolase treatment or no treatment (negative control). From that step all samples are processed in parallel.
Project description:It is generally assumed that mRNAs undergoing translation are protected from decay. Here, we show that mRNAs are, in fact, co-translationally degraded. This is a widespread and conserved process affecting most genes, where 5′–3′ transcript degradation follows the last translating ribosome, producing an in vivo ribosomal footprint. By sequencing the ends of 5′ phosphorylated mRNA degradation intermediates, we obtain a genome-wide drug-free measurement of ribosome dynamics. We identify general translation termination pauses in both normal and stress conditions. In addition, we describe novel codon-specific ribosomal pausing sites in response to oxidative stress that are dependent on the RNase Rny1. Our approach is simple and straightforward and does not require the use of translational inhibitors or in vitro RNA footprinting that can alter ribosome protection patterns. RNA samples were quantified according to their 5’modification. Samples were quantified using 2 alternative methods. 5PSeq (measures 5’P RNAs) and 5PSeq-fragmented (measures the sequencing bias present in any sample by randomly fragmenting RNA, re-phosphorilating the 5’ends and subjecting the sample to 5PSeq; it is used as a negative control). Different strains of S. cerevisiae and S. pombe samples were analyzed. Cells were grown both in rich media (YPD or YES) and synthetic defined media (SD). Cells were subjected to different treatments such as inhibition of translation elongation with cyclohexamide (CHX), oxidative stress (0.2 mM H2O2) or inhibition of histidine biosyntesys (3-AT; 100mM 3-amino-1,2,4-triazole). S. cerevisiae samples grown in rich media were also analyzed after CHX treatment and sucrose fractionation into monosome and polyribosome fractionation. All samples were analyzed in biological duplicates.
Project description:We study the effect of four QTN in RME1, IME1 & RSF1 that are causative for variation in sporulation efficiency. We investigate the relationship between genotype, gene expression and phenotype and whether the amount of gene expression variation explained by the sporulation QTN is predictive of the amount of phenotypic variation explained by them. RNA-Seq analysis of 4 replicates each of 16 allele replacement panel strains containing all combinations of the four sporulation QTN after 2 hours in sporulation medium.
Project description:The use of alternative polyadenylation sites is common and affects the post-transcriptional fate of mRNA, including its stability, localization, and translation. Here we present a method for genome-wide and strand-specific mapping of poly(A) sites and quantification of RNA levels at unprecedented efficiency by using an on-cluster dark T-fill procedure on the Illumina sequencing platform. Our method outperforms former protocols in quality and throughput, and reveals new insights into polyadenylation in Saccharomyces cerevisiae. Experimental benchmark of five different protocols (3tfill, bpmI, internal, rnaseq and yoon) for genome-wide identification of polyadenylation sites in Saccharomyces cerevisiae and transcript quantification. RNA was extracted from WT cells grown in glucose (ypd) or galactose (ypgal) as carbon source. The same RNA was used for 3 independent library constructions (technical replicates, rep).
Project description:Proteins are key molecular players in a cell, and their abundance is extensively regulated not just at the level of gene expression but also post-transcriptionally. Here, we describe a genetic screen in yeast that enables systematic characterization of how protein abundance regulation is encoded in the genome. The screen combines a CRISPR/Cas9 base editor to introduce point mutations with fluorescent tagging of endogenous proteins to facilitate a flow-cytometric readout. We first benchmarked base editor performance in yeast with individual gRNAs as well as in positive and negative selection screens. We then examined the effects of 16,452 genetic perturbations on the abundance of eleven proteins representing a variety of cellular functions. We uncovered hundreds of regulatory relationships, including a novel link between the GAPDH isoenzymes Tdh1/2/3 and the Ras/PKA pathway. Many of the identified regulators are specific to one of the eleven proteins, but we also found genes that, upon perturbation, affected the abundance of most of the tested proteins. While the more specific regulators usually act transcriptionally, broad regulators often have roles in protein translation. Overall, our novel screening approach provides unprecedented insights into the components, scale and connectedness of the protein regulatory network.
Project description:Purpose: The goals of this study were to determine whether the spliceosome interacts with non-intronic mRNAs Methods: RNAseq was performed on RNA that immunoprecipitated with the yeast SMD1 protein. Tandem-affinity-purified RNAs were extracted and RNAseq libraries were generated using the EpiCentre ScriptSeq kit (v1). We also performed RNAseq experiments on rRNA depleted total RNA extracted from an exosome mutant (rrp6M-NM-^T), a temperature-sensitive splicing mutant (prp40-1) and a parental strain (BY4741). The rRNA was depleted using the Invitrogen RiboMinus kit, according to manufactureres procedures. The depleted RNA was subsequently treated with Turbo DNAse I (Ambion) and RNAseq libraries were generated using the EpiCentre ScriptSeq kit (v1). Results: The SM RNAseq data identified a number of non-intronic mRNAs that appeard to be bound by the spliceosome. Among these was the BDF2 mRNA, which enocdes for a bromo-domain protein. BDF2 was highly enriched in both SM-IP datasets and was therefore analyzed in more detail. To determine if other non-intronic mRNAs could be regulated by the spliceosome, we analysed the transcriptome in the rrp6M-NM-^T, the prp40-1 and a parental strain. Bioinformatic analysis of these data sets revealed that roughly 1% of the non-intronic mRNAs in yeast could be targeted by the spliceosome. TopHat revealed cannonical splice junctions in roughly 30 non-intronic mRNAs, indicating that these messages are spliced. Conclusions: We demonstrate, for the first time, that the spliceosome can regulate expression of non-intronic mRNAs via one and/or two RNA cleavage events. We refer to this process as Spliceosome Mediated Decay (SMD). We report RNAseq data for two SM immunoprecipitation experiments and RNAseq datasets for the parental strain (BY4741), the prp40-1 mutant, and the rrp6M-NM-^T strain.
Project description:LncRNAs represent a major transcriptional output of the human genome, but the function of many of these elements is unknown. In this experiment, we have used the ‘CUT&RUN’ technique to quantify the changes in histone mark enrichment across the genome upon depletion of the lncRNA LINC00899 in HeLa cells. LINC00899 is of interest as its depletion results in mitotic delay, suggesting a role in mitotic progression. The CUT&RUN procedure uses antibodies to target a nuclease to the relevant protein binding site, cleaving the surrounding DNA for sequencing and yielding output equivalent to that of ChIP-seq. This experiment contains 2 replicate batches where each batch contains a sample with LINC00899 knocked down by RNA interference (RNAi); a RNAi negative control; a sample with LINC00899 knocked down with locked nucleic acid antisense oligonucleotides (LNA); and a LNA negative control. This was performed using antibodies against H3K4me3, H3K27ac, H3K36me3 and H3K27me3, as well as an IgG (goat-derived anti-rabbit) control. All samples in each batch were generated at the same time. Within each batch, all CUT&RUN experiments with the same knockdown were performed on nuclei obtained from the same cell culture. Independent cell cultures were used for experiments with different knockdown or in different batches.
Project description:Microbubbles are micron-sized bubbles generated using a fluidic oscillator. They have the potential to decrease the cost of biotechnology processes through decreasing the energy required for aeration and mixing. Propagation of yeast cells showed few morphological and transcriptomic changes when cultivated with either micro bubbles or regular bubbles. This experiment was designed to see if changes could be detected in the transcriptome when cells were cultivated on microbubbles and then split into two reactors for the fermentation phase where low levels of oxygen were provided during the fermentation phase using either micro bubbles or regular bubbles