Project description:To obtain a comprehensive survey of the structure and expression level of transcripts across the yeast genome, we used tiling arrays to profile wild-type transcriptomes in ethanol (YPE), glucose (YPD, SDC), and galactose (YPGal), which together encompass the main laboratory growth conditions of yeast. Transcript start and end positions were mapped to the genome by a segmentation algorithm and subsequent manual curation. To identify Cryptic Unstable Transcripts (CUTs), profiles were also measured for a deletion mutant of Rrp6, an important component of the nuclear exosome, which is involved in the degradation of CUTs. Expression profiles are provided in a searchable web-database (http://steinmetzlab.embl.de/NFRsharing).
Project description:Transcription profile in YPD media of 48 segregants spores obtained from a cross of the yeast strains S96 and YJM789. These spores are a subset of those published by Mancera et al, Nature, 2008. Two CEL files were mislabelled: eQTL_080822_spore_38B.CEL and eQTL_080826_spore_21C.CEL, actually spores 24A and 8D respectively. The correct spore IDs are in the sample annotation (under StrainOrLine).
Project description:To profile genome-wide allele-specific expression in an unbiased manner we designed a high-resolution yeast tiling microarray that covers the genomes of both the laboratory strain S288c and the recently sequenced clinical isolate YJM789. This array design allows simultaneous expression profiling of allelic variants in a heterozygous hybrid strain. We hybridized cDNA from the heterozygous Y/S and from the homozygous S and Y strains grown in rich medium (YPD). Strand specificity during sample preparation was maintained by inclusion of actinomycin D during reverse transcription to prevent spurious synthesis of second strand cDNA.
Project description:Widely transcribed and compact genomes face the major challenge of coping with frequent overlapping or concurrent transcription events. Efficient and timely transcription termination is crucial to control pervasive transcription. In yeast, RNA polymerase II (RNAPII) termination mainly occurs via two pathways, one generating mRNAs and one dedicated to non-coding RNAs, and is triggered by signals that are recognized on the nascent RNA by a specific complex. We describe here a novel pathway of RNAPII transcription termination that is triggered by the binding to the DNA of the transcriptional activator Reb1p. We show that termination follows road-block induced pausing of RNAPII and requires ubiquitylation of RNAPII. The released RNAs are rapidly degraded, which defines a new class of cryptic unstable transcripts. We show that Reb1p-dependent termination can prevent transcriptional interference. This work reveals a novel role for Reb1p and a new paradigm for preserving the functional integrity of nucleosome free regions.
Project description:Temporal expression profiling during sporulation for TAO3(4477C) allele replacement strains in S288c. Raw gene expression data CEL files for control TAO3(4477G) allele strain are given in E-MTAB-3454 (see 9 array files from \S_Spo0h0m_Scerevisiae_tlg.CEL\ to \S_Spo8h30m_Scerevisiae_tlg.CEL\).
Project description:Yeast Npl3 is a highly abundant RNA binding protein, related to metazoan SR proteins, with reported functions including transcription elongation, splicing and RNA 3’ end processing. To identify direct targets and functions for Npl3, we used UV crosslinking and analysis of cDNA (CRAC) to map precise RNA binding sites. Npl3 binds diverse RNA species, at sites indicative of roles in both early pre-mRNA processing and 3’ end formation on mRNAs and ncRNAs. Consistent with this, tiling array and RNAPII binding data revealed 3’ extended mRNA and snoRNA transcripts in the absence of Npl3. This reflected transcriptional readthrough by RNAPII, and extension and stabilization of cryptic unstable transcript (CUT) long noncoding RNAs. Transcription readthrough was widespread, often resulting in down-regulation of neighboring genes. We conclude that Npl3 is required for the formation of a termination-competent RNA, affecting both coding and noncoding RNAs.
Project description:Recent transcription profiling studies have revealed an unanticipatedly large proportion of antisense transcription across eukaryotic and bacterial genomes. However, the extent and significance of antisense transcripts is controversial partly because experimental artifacts are suspected. Here, we present a method to generate clean genome-wide transcriptome profiles, using actinomycin D (ActD) during reverse transcription. We show that antisense artifacts appear to be triggered by spurious synthesis of second-strand cDNA during reverse transcription reactions. Strand-specific hybridization signals obtained from Saccharomyces cerevisiae tiling arrays were compared between samples prepared with and without ActD. Use of ActD removed about half of the detectable antisense transcripts, consistent with their being artifacts, while sense expression levels and about 200 antisense transcripts were not affected. Our findings thus facilitate a more accurate assessment of the extent and position of antisense transcription, towards a better understanding of its role in cells.