Plasticity of Mitochondrial DNA Inheritance and its Impact on Nuclear Gene Transcription in Yeast Hybrids grown on YP Glycerol 28C
ABSTRACT: Mitochondrial DNA (mtDNA) in budding yeast is biparentally inherited, but colonies rapidly lose one type of parental mtDNA, becoming homoplasmic. Therefore, hybrids between different yeast species possess two homologous nuclear genomes, but only one type of mitochondrial DNA. We hypothesise that the choice of mtDNA retention is influenced by its contribution to hybrid fitness in different environments, and that the allelic expression of the two nuclear sub-genomes is affected by the presence of different mtDNAs in hybrids. Here, we crossed Saccharomyces cerevisiae with S. uvarum under different environmental conditions and examined the plasticity of the retention of mtDNA in each hybrid.
Project description:We did transcription profiling on the effect of rlm1 (MAPK Slt2 transcription factor) deletion and swi3 (component of SWI/SNF complex involved in chromatin remodeling) deletion in genes involved in cell wall stress (Congo Red) response. Three biological samples were analyzed for each condition, and a microarray experiment were carried out for each sample 1. absence of the drug 2. presence of 30 µg/ml of Congo Red
Project description:This experiment was performed in order to assess the specificity of Rad9 binding to S. cerevisiae genome. In another ChIP-chip experiment in SC BCS BPS growth conditions we have found Rad9 present to a significant number of genomic loci with a bias to transcriptionally active regions. In order to see if that pattern was random and depended or not on the activity state of the genes, we conducted a Rad9 ChIP on chip experiment with the strain grown in medium with galactose instead of glucose, where it is known that particular gene groups are transcriptionally activated. We then compared to the results of our previous experiment where the strain was grown in glucose.
Project description:The experiment describes the transcriptional response of Saccharomyces cerevisiae BY4741 and of the deletion mutant Δhaa1 following an incubation in the presence of 50 mM acetic acid (at pH 4.0)
Project description:Mitochondria are vital in providing cellular energy via their oxidative phosphorylation system, which requires the coordinated expression of genes encoded by both the nuclear and mitochondrial genomes (mtDNA). Transcription of the circular mammalian mtDNA depends on a single mitochondrial RNA polymerase (POLRMT). Although the transcription initiation process is well understood, it remains highly controversial if POLRMT also serves as the primase for initiation of mtDNA replication. In the nucleus, the RNA polymerases needed for gene expression have no such role. Conditional knockout of Polrmt in heart results in severe mitochondrial dysfunction causing dilated cardiomyopathy in young mice. We further studied the molecular consequences of different expression levels of POLRMT and found that POLRMT is essential for primer synthesis to initiate mtDNA replication in vivo. Furthermore, transcription initiation for primer formation has priority over gene expression. Surprisingly, mitochondrial transcription factor A (TFAM) exists in an mtDNA-free pool in the Polrmt knockout mice. TFAM levels remain unchanged despite strong mtDNA depletion and TFAM is thus protected from degradation of the AAA+ Lon protease in absence of POLRMT. Lastly, mitochondrial transcription elongation factor (TEFM) can compensate for a partial depletion of POLRMT in heterozygous Polrmt knockout mice, indicating a direct regulatory role for this factor in transcription. In conclusion, we present here the first in vivo evidence that POLRMT has a key regulatory role in replication of mammalian mtDNA and is part of a mechanism that provides a switch between RNA primer formation for mtDNA replication and mtDNA expression. Isolated heart mitochondria from three control mice (L/L) and three Polrmt knockout mice (L/L, cre), aged 3-4 weeks, were sequenced and analyzed for differential expression.
Project description:Meiotic recombination hotspots are associated with histone post-translational modifications and open chromatin. However, it remains unclear how histone modifications and chromatin structure directly regulate meiotic recombination. Here, we identify acetylation of histone H4 at Lys44 (H4K44ac) as a new histone modification, occurring on the nucleosomal lateral surface. We show that H4K44ac is specific to yeast sporulation, rising during yeast meiosis and displaying genome-wide enrichment at recombination hotspots in meiosis. The H4K44 residue is required for normal meiotic recombination, for normal levels of double strand breaks during meiosis, and for optimal sporulation. Non-modifiable substitution H4K44R results in reduced MNase digestion and decreased binding of recombination-associated proteins at hotspots. Our results show that H4K44ac creates an accessible chromatin environment for key proteins to facilitate meiotic recombination. One sample, H4K44ac chIP from 4hrs sporulation yeast and one background H4 chIP from the same, two replicates each Two replicates each of H3K4me3 and H3K56ac chIP-seq in WT and H4K44->R mutant yeast, with two replicates of H3 chIP-seq in each genetic background Two replicates each of Rad51 chIP-seq in WT and H4K44->R mutant yeast with a single replicate of accompanying input DNA in each genetic background
Project description:Investigation of whole genome gene expression level changes in three S. cerevisiae Y55 mutants, compared to the wild-type strain. The UV-induced mutations enable the mutant strains to ferment high-gravity maltose faster than the WT. The mutants analyzed in this study are further described in Baerends, R.J.S., J.L. Qiu, L. Gautier, and A. Brandt. A high-throughput system for screening of fast-fermenting Saccharomyces cerevisiae strains. Manuscript in preparation. A single-dye 12-plex array chip study using double-stranded DNA prepared from messenger RNA purified from total RNA recovered from three separate Saccharomyces cerevisiae Y55 wild-type cultures and 3x three separate cultures each corresponding to a fast-fermenting UV-induced mutant (mutant 1, 2 and 3), during fermentation of high-gravity maltose at day 2. Each array on the 12-plex chip measures the expression level of 5,777 genes from Saccharomyces cerevisiae S288C with eight 60-mer probes per gene, with three-fold technical redundancy.
Project description:We compared the RNA expression profile from a Saccharomyces cerevisiae yeast strain (3xABF2) containing two (2) extra copies of Abf2p, a mtDNA maintenance factor, to the signal from its wild type counterpart (14ww). The two strains used have been described in Genetics 148: 1763-1776.
Project description:We studied the transcriptional profile in response to acute PtdIns-4,5P2 depletion induced by heterologous expression of a plasma membrane-directed version of mammalian PI3K catalytic subunit (p110α-CAAX). Three biological samples were analyzed for samples expressing for 4 hours p110α-CAAX (PI3K) versus the kinase dead mutant p110α-CAAX K802R (KD), and one microarray experiment was carried out for each sample.
Project description:Mitochondria derived from Saccharomyces cerevisiae grown on either a non-fermentable (glycerol) or a fermentable (glucose) carbon source were cross-linked with BS3. Additionally, by using a stable-isotope labelled quantitative cross-linking approach, we were able to quantify differences in protein-protein cross-links in mitochondria according to the growth condition. Furthermore, so far uncharacterized yeast proteins were put into biological context based on their cross-linking pattern.
Project description:Mitochondrial biogenesis is regulated by signaling pathways sensitive to extracellular conditions and to the internal environment of the cell. We found that deletion of protein phosphatase 2A (PP2A) or of protein phosphatase 6 (PP6) diminishes the nuclear transcriptional response associated with mtDNA damage. Six samples were analyzed to determine message RNA levels.