Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitute 1% of all described fungal species.
Heterochromatin is a tightly packed form of DNA or condensed DNA, which comes in multiple varieties. These varieties lie on a continuum between the two extremes of constitutive heterochromatin and facultative heterochromatin. Both play a role in the expression of genes. Because it is tightly packed, it was thought to be inaccessible to polymerases and therefore not transcribed; however, according to Volpe et al. (2002), and many other papers since, much of this DNA is in fact transcribed, but it is continuously turned over via RNA-induced transcriptional silencing (RITS). Recent studies with electron microscopy and OsO4 staining reveal that the dense packing is not due to the chromatin.
Saccharomyces cerevisiae is a species of yeast. The species has been instrumental in winemaking, baking, and brewing since ancient times. It is believed to have been originally isolated from the skin of grapes. It is one of the most intensively studied eukaryotic model organisms in molecular and cell biology, much like Escherichia coli as the model bacterium. It is the microorganism behind the most common type of fermentation. S. cerevisiae cells are round to ovoid, 5–10 μm in diameter. It reproduces by budding.
Schizosaccharomyces pombe, also called "fission yeast", is a species of yeast used in traditional brewing and as a model organism in molecular and cell biology. It is a unicellular eukaryote, whose cells are rod-shaped. Cells typically measure 3 to 4 micrometres in diameter and 7 to 14 micrometres in length. Its genome, which is approximately 14.1 million base pairs, is estimated to contain 4,970 protein-coding genes and at least 450 non-coding RNAs.
A pre-replication complex (pre-RC) is a protein complex that forms at the origin of replication during the initiation step of DNA replication. Formation of the pre-RC is required for DNA replication to occur. Complete and faithful replication of the genome ensures that each daughter cell will carry the same genetic information as the parent cell. Accordingly, formation of the pre-RC is a very important part of the cell cycle.
Subtelomeres are segments of DNA between telomeric caps and chromatin.
The Biological General Repository for Interaction Datasets (BioGRID) is a curated biological database of protein-protein interactions, genetic interactions, chemical interactions, and post-translational modifications created in 2003 (originally referred to as simply the General Repository for Interaction Datasets by Mike Tyers, Bobby-Joe Breitkreutz, and Chris Stark at the Lunenfeld-Tanenbaum Research Institute at Mount Sinai Hospital. It strives to provide a comprehensive curated resource for all major model organism species while attempting to remove redundancy to create a single mapping of data. Users of The BioGRID can search for their protein, chemical or publication of interest and retrieve annotation, as well as curated data as reported, by the primary literature and compiled by in house large-scale curation efforts. The BioGRID is hosted in Toronto, Ontario, Canada and Dallas, Texas, United States and is partnered with the Saccharomyces Genome Database, FlyBase, WormBase, PomBase, and the Alliance of Genome Resources. The BioGRID is funded by the NIH and CIHR. BioGRID is an observer member of the International Molecular Exchange Consortium.
The mating-type locus is a specialized region in the genomes of some yeast and other fungi, usually organized into heterochromatin and possessing unique histone methylation patterns. The genes in this region regulate the mating type of the organism and therefore determine key events in its life cycle, such as whether it will reproduce sexually or asexually. In fission yeast such as S. pombe, the formation and maintenance of the heterochromatin organization is regulated by RNA-induced transcriptional silencing, a form of RNA interference responsible for genomic maintenance in many organisms. Mating type regions have also been well studied in budding yeast S. cerevisiae and in the fungus Neurospora crassa.
Spo11 is a protein that in humans is encoded by the SPO11 gene. Spo11, in a complex with mTopVIB, creates double strand breaks to initiate meiotic recombination. Its active site contains a tyrosine which ligates and dissociates with DNA to promote break formation. One Spo11 protein is involved per strand of DNA, thus two Spo11 proteins are involved in each double stranded break event.
Chromosome segregation is the process in eukaryotes by which two sister chromatids formed as a consequence of DNA replication, or paired homologous chromosomes, separate from each other and migrate to opposite poles of the nucleus. This segregation process occurs during both mitosis and meiosis. Chromosome segregation also occurs in prokaryotes. However, in contrast to eukaryotic chromosome segregation, replication and segregation are not temporally separated. Instead segregation occurs progressively following replication.
In enzymology, an initiation-specific alpha-1,6-mannosyltransferase is an enzyme that catalyzes the chemical reaction in which an alpha-D-mannosyl residue is transferred from GDP-mannose to a lipid-linked oligosaccharide, being linked by an alpha-1,6-D-mannosyl-D-mannose bond.
Wee1 is a nuclear kinase belonging to the Ser/Thr family of protein kinases in the fission yeast Schizosaccharomyces pombe. Wee1 has a molecular mass of 96 kDa and is a key regulator of cell cycle progression. It influences cell size by inhibiting the entry into mitosis, through inhibiting Cdk1. Wee1 has homologues in many other organisms, including mammals.
Saccharomyces paradoxus is a wild yeast and the closest known species to the baker's yeast Saccharomyces cerevisiae. It is used in population genomics and phylogenetic studies to compare its wild characteristics to laboratory yeasts.
The Honourable John Murdoch Mitchison FRS, FRSE was a British zoologist.
Mitsuhiro Yanagida ForMemRS is a Japanese molecular biologist known for research on cell cycle and chromosome structure using the fission yeast Schizosaccharomyces pombe. He was elected as a foreign member of the Royal Society on 11 May 2000.
In molecular biology the protein domain XPG refers to, in this case, the N-terminus of XPG. The XPG protein can be corrected by a 133 kDa nuclear protein, XPGC. XPGC is an acidic protein that confers normal ultraviolet (UV) light resistance. It is a magnesium-dependent, single-strand DNA endonuclease that makes structure-specific endonucleolytic incisions in a DNA substrate containing a duplex region and single-stranded arms. XPGC cleaves one strand of the duplex at the border with the single-stranded region.
Urs Leupold was a Swiss geneticist whose studies of the fission yeast Schizosaccharomyces pombe were instrumental in establishing this organism as a key model system for eukaryotic cell and molecular biology. Leupold began his studies of S. pombe in 1946 upon encouragement by Øjvind Winge. In 1947, Leupold determined that a culture of S. pombe str. liquefaciens contained strains expressing four distinct mating types: h40, h90, h+, and h−. Most current S. pombe laboratory strains are derived from the h90, h+, and h− strains known as 968, 975, and 972.
PomBase is a model organism database that provides online access to the fission yeast Schizosaccharomyces pombe genome sequence and annotated features, together with a wide range of manually curated functional gene-specific data. The PomBase website was redeveloped in 2016 to provide users with a more fully integrated, better-performing service.
Aerobic fermentation or aerobic glycolysis is a metabolic process by which cells metabolize sugars via fermentation in the presence of oxygen and occurs through the repression of normal respiratory metabolism. Preference of aerobic fermentation over aerobic respiration is referred to as the Crabtree effect in yeast, and is part of the Warburg effect in tumor cells. While aerobic fermentation does not produce adenosine triphosphate (ATP) in high yield, it allows proliferating cells to convert nutrients such as glucose and glutamine more efficiently into biomass by avoiding unnecessary catabolic oxidation of such nutrients into carbon dioxide, preserving carbon-carbon bonds and promoting anabolism.
ERG5 or Sterol 22-desaturase is a cytochrome P450 enzyme in the ergosterol biosynthesis pathway of fungi Saccharomyces cerevisiae, with the CYP Symbol CYP61A1. CYP61A1 is one of only three P450 enzyme found in baker's yeast, the other two are CYP51F1 and CYP56A1. The ortholog in Schizosaccharomyces pombe, was named CYP61A3 for historical reasons, and is only one of two P450 enzyme found with CYP51F1. ERG5 catalyzes the C22-C23 double bond formation on the sterol side chain of ergostatrienol to convert it into ergostatetraenol, then the C24 double bond of ergostatetrenol will be hydrogenation reduced into ergosterol by ERG4.
