Project description:Effect of FLO8 or MSS11 deletion and -overexpression on yeast transcript profiles compared to wild type in laboratory yeast strains Σ1278b and S288c.
Project description:The general pathways of eukaryotic mRNA decay occur via deadenylation followed by 3’ to 5’ degradation or decapping, although some endonuclease sites have been identified in metazoan mRNAs. To determine the role of endonucleases in mRNA degradation in Saccharomyces cerevisiae, we mapped 5’ monophosphate ends on mRNAs in wild-type and dcp2∆ xrn1∆ yeast cells, wherein mRNA endonuclease cleavage products are stabilized. This led to three important observations. First, only few mRNAs that undergo low level endonucleotyic cleavage were observed suggesting that endonucleases are not a major contributor to yeast mRNA decay. Second, independent of known decapping enzymes, we observed low levels of 5’ monophosphates on some mRNAs suggesting that an unknown mechanism can generate 5' exposed ends, although for all substrates tested Dcp2 was the primary decapping enzyme. Finally, we identified debranched lariat intermediates from intron-containing genes, demonstrating a significant discard pathway for mRNAs during the second step of pre-mRNA splicing, which is a potential new step to regulate gene expression.
Project description:Effect of either FLO8 or MSS11 deletion and -overexpression on yeast transcript profiles compared to wild type in laboratory yeast strains Σ1278b and S288c - also the effect of FLO11 (MUC1) overexpression in the Σ1278b genetic background The aim of this study was to (1) perform a repeat analysis (to improve statistical analysis of these data sets) similar to data submitted previously (GSE17716) and also (2) study the effect of FLO11 over-expression on the transcriptome. Background: The outer cell wall of the yeast Saccharomyces cerevisiae serves as the interface with the surrounding environment and defines cell-cell and cell-surface interactions. Many of these interactions are facilitated by specific adhesins that belong to the Flo protein family. This family of mannoproteins has been implicated in phenotypes such as flocculation and substrate adhesion as well as pseudohyphal growth. Genetic data strongly suggest that individual Flo proteins are responsible for many specific cellular adhesion phenotypes. However, it remains unclear whether such phenotypes are determined solely by the nature of the expressed FLO genes or rather the result of a combination of FLO gene expression and other cell wall properties and cell wall proteins. Mss11p has been shown to be a central element of FLO1 and FLO11 gene regulation and acts together with the cAMP-PKA-dependent transcription factor Flo8p. We use genome wide transcript analysis to identify genes that are direct ly or indirectly regulated by Mss11p in the genetic backgrounds: Sigma1278b and S288c. Sigma 1278b is the strain historically used for the study of pseudohyphae (FLO11 expression) but we also included S288c as this strain is widely used in the research community and was used to determine the first full genome sequence (Thus correspond with SGD information). We also compare this data with transcriptome data from Sigma 1278b yeast over-expressing FLO8 to compare similarities/differences between these two signalling factors. Finally the effect of FLO11 over-expression in Sigma1278b on global transcription is studied so that we can differentiate between "direct" gene targets of Flo8p or Mss11p, and those regulated as a result by the "indirect" effect caused by modified cell wall Flo11p levels.
Project description:Post-transcriptional modifications to messenger RNAs (mRNAs) have the potential to alter the biological function of this important class of biomolecules. The study of mRNA modifications is a rapidly emerging field, and the full complement of chemical modifications in mRNAs is not yet established. We sought to identify and quantify the modifications present in yeast mRNAs using an ultra-high performance liquid chromatography tandem mass spectrometry method to detect 40 nucleoside variations in parallel. We observe six modified nucleosides with high confidence in highly purified mRNA samples (N7-methylguanosine, N6-methyladenosine, 2’-O-methylguanosine, 2’-O-methylcytidine, N4-acetylcytidine and 5-formylcytidine), and identify the yeast protein responsible for N4-acetylcytidine incorporation in mRNAs, Rra1. Additionally, we find that mRNA modification levels change in response to heat shock, glucose starvation and/or oxidative stress. This work expands the repertoire of potential chemical modifications in mRNAs, and highlights the value of integrating mass spectrometry tools in the mRNA modification discovery and characterization pipeline.
Project description:Aneuploidy and aging are correlated; however, a causal link between these two phenomena has remained elusive. Here we show that yeast disomic for a single native yeast chromosome generally have a decreased replicative lifespan. In addition, the extent of this lifespan deficit correlates with the size of the extra chromosome. We identified a mutation in BUL1 that rescues both the lifespan deficit and a protein trafficking defect in yeast disomic for chromosome 5. Bul1 is an E4 ubiquitin ligase adaptor involved in a protein quality-control pathway that targets membrane proteins for endocytosis and destruction in the lysosomal vacuole thereby maintaining protein homeostasis. Concurrent suppression of the aging and trafficking phenotypes suggests that disrupted membrane protein homeostasis in aneuploid yeast may contribute to their accelerated aging. The data reported here demonstrate that aneuploidy can impair protein homeostasis, shorten lifespan, and may contribute to age-associated phenotypes.