Analyzing the dose-dependence of the Saccharomyces cerevisiae global transcriptional response to MMS and IR
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ABSTRACT: Wt S. cerevisiae cells from a W303 background were exposed to multiple doses of MMS and Gamma Radiation and their global transcriptional response was measured Keywords: dose response
Project description:BackgroundOne of the most crucial tasks for a cell to ensure its long term survival is preserving the integrity of its genetic heritage via maintenance of DNA structure and sequence. While the DNA damage response in the yeast Saccharomyces cerevisiae, a model eukaryotic organism, has been extensively studied, much remains to be elucidated about how the organism senses and responds to different types and doses of DNA damage. We have measured the global transcriptional response of S. cerevisiae to multiple doses of two representative DNA damaging agents, methyl methanesulfonate (MMS) and gamma radiation.ResultsHierarchical clustering of genes with a statistically significant change in transcription illustrated the differences in the cellular responses to MMS and gamma radiation. Overall, MMS produced a larger transcriptional response than gamma radiation, and many of the genes modulated in response to MMS are involved in protein and translational regulation. Several clusters of coregulated genes whose responses varied with DNA damaging agent dose were identified. Perhaps the most interesting cluster contained four genes exhibiting biphasic induction in response to MMS dose. All of the genes (DUN1, RNR2, RNR4, and HUG1) are involved in the Mec1p kinase pathway known to respond to MMS, presumably due to stalled DNA replication forks. The biphasic responses of these genes suggest that the pathway is induced at lower levels as MMS dose increases. The genes in this cluster with a threefold or greater transcriptional response to gamma radiation all showed an increased induction with increasing gamma radiation dosage.ConclusionAnalyzing genome-wide transcriptional changes to multiple doses of external stresses enabled the identification of cellular responses that are modulated by magnitude of the stress, providing insights into how a cell deals with genotoxicity.
Project description:Proteomic analysis of the extracellular matrix of Saccharomyces cerevisiae W303-1A Wt and the isogenic mutant strain gup1Δ during the development of multicellular overlays.
Project description:The cellular response to treatment with DNA-damaging substances at low concentrations which are genotoxic but do not have a strong cytotoxic effect are of special interest. In addition, environmental variations that influence growth conditions, e.g. different media, and individual fitness, e.g. different strains, are likely to influence and modulate the adverse effects of individual DNA damaging substances. At sub-cytotoxic levels, DNA damaging substances play an important role in the accumulation of genomic mutations. In longer living organisms, like humans and other mammals, exposure to DNA damaging substances over extended period of time is a critical factor that contributes to the development of various diseases and in particular of tumors. The aim of our work was to study how strain background and growth conditions influence respond to DNA damage caused by low doses of MMS and which part of these changes is responsible for their sensitivity to toxic conditions. We analyzed sensitivity of two yeast strains FF18984 and BY4742 to MMS in media with limited and full nutrient availability. Keywords: Yeast, S.cerevisiae, MMS, stress response, DNA damage
Project description:The treatment of methyl methane sulfonate (MMS) increases sensitivity to the DNA damage which, further leads to the cell death followed by a cell cycle delay. Delay in the cell cycle is because of the change in global transcription regulation which results into proteome change. There are several microarray studies on the transcriptome changes after MMS treatment, but very few studies are reported related to proteome change. The proteome analysis in this report identified subgroups of proteins, belonging to known cell cycle regulators, metabolic pathways and protein folding. About 53 proteins were identified by MS/MS and found that 36 of them were induced, 10 were repressed and few of them showed insignificant change. Our results indicated the change in the interactome as well as phosphorylation status of carboxy terminal domain (CTD) of RNA Polymerase II (RNAP-II) after MMS treatment. The RNAP-II complex was affinity purified and ~1640 peptides were identified using nano LC/MS corresponding to 27 interacting proteins along with the twelve RNAP-II subunit. These identified proteins participated in the repair of the damage, changes the function of the main energetic pathways and the carbon flux in various end products. The main metabolic enzymes in the glycolysis, pyruvate phosphate and amino acid biosynthesis pathways showed significant change. Our results indicate that DNA damage is somehow related to these pathways and is co-regulated simultaneously.
Project description:Transcriptional profiling of Saccharomyces cerevisiae cells comparing the W303-1A wildtype with the W303-1A double mutant for MSN2 and MSN4 during zinc deficient conditions Keywords: Genetic modification with zinc limitation