Project description:This experiment aims to map nucleosome positions and comparison of the same in WT NORMAL GROWTH vs WT-NUTRIENT STARVATION/isw1∆2∆ MUTANT/rsc4-∆4 MUTANT in Saccharomyces cerevisiae using a custom designed tiling array on Agilent plat form. The corresponding platform is submitted to GEO under Geo-ID GPL15842. 60mer probes with variable tiling density were designed for all the genes transcribed by RNA polymerase III. Each gene is tiled along with its 1kb downstream and upstream region with the exceptions of RPR1, SCR1, RDN5(1-6) and SNR52. Mononucleosomal DNA and size matched naked DNA was competitively hybridized to the array. Data was extracted and normalized log ratios were calculated using Agilent sofware. Normalized log2 ratio data was used in MLM to detection nucleosome positions.
Project description:Changes in RNA levels during osmotic stress were investigated. Total RNA was extracted from a wild-type yeast strain before and after treatment with 0.4 M NaCl and the corresponding cDNAs were hybridazed on Tiling arrays. In particular, for all the intron-containing genes, the changes in the levels of intron signal in stressed cells related to the intron signal in the non-stressed cells, and the changes in the levels of exon signal in stresses cells related to the exon signal in non-stressed cells were investigated. The supplementary bar file contains the ratios between stress signals respect to non-stress signals, using the average of the 3 biological replicas.
Project description:We investigated the genome-wide distribution of Okazaki fragments in the commonly used laboratory Saccharomyces cerevisiae strain S288C to study the DNA replication model adopted by the budding yeast. The method based upon lambda exonuclease digestion for purification of RNA-primed replication intermediates was first improved to be suitable for the purification of Okazaki fragments. Then, we used this improved method to purify Okazaki fragments from S288C yeast cells, followed by Illumina sequencing. We found that the expected asymmetric distribution of Okazaki fragments around confirmed replication origins, which was derived from the semi-discontinuous DNA replication model, was not observed on S. cerevisiae chromosomes. Even around two highly efficient replication origins, ARS522 and ARS416, the ratios of Okazaki fragments on both strands were inconsistent with the semi-discontinuous DNA replication model. Our study supported the discontinuous DNA replication model. Besides, we also observed that Okazaki fragments were overpresented in the transcribed regions in S. cerevisiae mitochondrial genome, which indicated the interplay between transcription and DNA replication.
Project description:BackgroundMatings between different Saccharomyces sensu stricto yeast species produce sexually sterile hybrids, so individuals should avoid mating with other species. Any mechanism that reduces the frequency of interspecific matings will confer a selective advantage. Here we test the ability of two closely-related Saccharomyces sensu stricto species to select their own species as mates and avoid hybridisation.ResultsWe set up mate choice tests, using five independently isolated pairs of species, in which individual germinating spores were presented with the opportunity to mate either with a germinating spore of their own species or with a germinating spore of the other species. For all five strain pairs, whether a S. cerevisiae or S. paradoxus occupies the role of "chooser" strain, the level of hybridisation that is observed between the two species is significantly lower than would be expected if mates were selected at random. We also show that, overall, S. cerevisiae exhibited a stronger own-species preference than S. paradoxus.ConclusionPrezygotic reproductive isolation is well known in higher organisms but has been largely overlooked in yeast, an important model microbe. Here we present the first report of prezygotic reproductive isolation in Saccharomyces. Prezygotic reproductive isolation may be important in yeast speciation or yeast species cohesion, and may have evolved to prevent wasted matings between different species. Whilst yeast has long been used as a genetic model system, little is known about yeast in the wild. Our work sheds light on an interesting aspect of yeast natural behaviour: their ability to avoid costly interspecific matings.
Project description:We determined that extrachromosomal 2μ plasmid was present in 67 of the Saccharomyces cerevisiae 100-genome strains; in addition to variation in the size and copy number of 2μ, we identified three distinct classes of 2μ. We identified 2μ presence/absence and class associations with populations, clinical origin and nuclear genotypes. We also screened genome sequences of S. paradoxus, S. kudriavzevii, S. uvarum, S. eubayanus, S. mikatae, S. arboricolus and S. bayanus strains for both integrated and extrachromosomal 2μ. Similar to S. cerevisiae, we found no integrated 2μ sequences in any S. paradoxus strains. However, we identified part of 2μ integrated into the genomes of some S. uvarum, S. kudriavzevii, S. mikatae and S. bayanus strains, which were distinct from each other and from all extrachromosomal 2μ. We identified extrachromosomal 2μ in one S. paradoxus, one S. eubayanus, two S. bayanus and 13 S. uvarum strains. The extrachromosomal 2μ in S. paradoxus, S. eubayanus and S. cerevisiae were distinct from each other. In contrast, the extrachromosomal 2μ in S. bayanus and S. uvarum strains were identical with each other and with one of the three classes of S. cerevisiae 2μ, consistent with interspecific transfer.
Project description:The phosphorylation status of a protein is highly regulated and is determined by the opposing activities of protein kinases and protein phosphatases within the cell. While much is known about the protein kinases found in Saccharomyces cerevisiae, the protein phosphatases are much less characterized. Of the 127 protein kinases in yeast, over 90% are in the same evolutionary lineage. In contrast, protein phosphatases are fewer in number (only 43 have been identified in yeast) and comprise multiple, distinct evolutionary lineages. Here we review the protein phosphatase families of yeast with regard to structure, catalytic mechanism, regulation, and signal transduction participation.
Project description:Ubiquitination is an important post-translational modification involved in diverse biological processes. Therefore, genomewide representation of the ubiquitination system for a species is important.SCUD is a web-based database for the ubiquitination system in Saccharomyces cerevisiae (Baker's yeast). We first searched for all the known enzymes involved in the ubiquitination process in yeast, including E1, E2, E3, and deubiquitination enzymes. Then, ubiquitinated substrates were collected by literature search. Especially, E3 and deubiquitination enzymes are classified into classes and subclasses by their shared domains and unique functions. As a result, 42 different E3 enzymes were grouped into corresponding classes and subclasses, and 940 ubiquitinated substrates including mutant substrates were identified. All the enzyme and substrate information are interconnected by hyperlinks, which makes it easy to view the enzyme-specific ubiquitination information.This database aims to represent a comprehensive yeast ubiquitination system, and is easily expandable with the further experimental data. We expect that this database will be useful for the research on the ubiquitination systems of other higher organisms. SCUD is accessible at http://scud.kaist.ac.kr.