1. Cytochrome alpha 3 in whole-cell suspensions of the fission yeast Schizosaccharomyces pombe reacted in the reduced form with CO to give a photodissociable CO complex with absorption maxima at 429, 543 and 591 nm in CO-liganded reduced-minus-reduced difference spectra. 2. Other CO-bound haemoproteins, cytochromes P-420 and P-450, were not photodissociated under the conditions employed. 3. Measurements of the rates of reassociation of CO with cytochrome alpha 3 after flash photolysis over the temperature range from −101 to −109 degrees C gave a value for Eact. of 28.6 kJ/mol. 4. Between −94 and −106 degrees C, O2 reacted with cytochrome oxidase in intact cells to give an oxygenated intermediate (compound A). 5. At −70 degrees C compound A was converted into a second spectrally distinct intermediate (compound B). 6. Electron transport, indicated by the oxidation of cytochromes alpha + alpha 3 and cytochrome c, did not occur until the temperature was raised to −50 degrees C. 7. At ...
1. We used 11 different inhibitors of energy conservation as inhibitors of ATPase (adenosine triphosphatase) in extracts of Schizosaccharomyces pombe obtained from cells at different stages of the cell cycle. 2. All the inhibitors showed cell-cycle-dependent variations in their I50 values (microng of inhibitor/mg of protein giving 50% inhibition of inhibitor-sensitive ATPase at pH 8.6). 3. From the sensitivity profiles through the cell cycle it was concluded that: (a) oligomycin, venturicidin, triethyltin sulphate and dibutylchloromethyltin chloride all act at closely associated site(s); (b) NN-dicyclohexylcarbodi-imide and leucinostatin both act at a similar site, which is, however, distinct from that at which other inhibitors of the membrane factor (Fo) act. 4. The variations in I50 values for efrapeptin closely followed changes in specific activity of ATPase, as would be expected for an inhibitor acting at catalytic sites; these fluctuations were different from those for aurovertin, Dio-9, ...
Active in the repair of DNA damage and in mating-type switching. Probably involved in the repair of DNA double-strands breaks. Has a role in promoting S phase completion.
Binds specifically to cytosolic chaperonin (c-CPN) and transfers target proteins to it. Binds to nascent polypeptide chain and promotes folding in an environment in which there are many competing pathways for nonnative proteins (By similarity).
TY - JOUR. T1 - Degradation of HMG-CoA reductase-induced membranes in the fission yeast, Schizosaccharomyces pombe. AU - Lum, Pek Yee. AU - Wright, Robin. PY - 1995/10/1. Y1 - 1995/10/1. N2 - Elevated levels of certain membrane proteins, including the sterol biosynthetic enzyme HMG-CoA reductase, induce proliferation of the endoplasmic reticulum. When the amounts of these proteins return to basal levels, the proliferated membranes are degraded, but the molecular details of this degradation remain unknown. We have examined the degradation of HMG-CoA reductase-induced membranes in the fission yeast, Schizosaccharomyces pombe. In this yeast, increased levels of the Saccharomyces cerevisiae HMG-CoA reductase isozyme encoded by HMG1 induced several types of membranes, including karmellae, which formed a cap of stacked membranes that partially surrounded the nucleus. When expression of HMG1 was repressed, the karmellae detached from the nucleus and formed concentric, multilayered membrane whorls that ...
Project Information The Schizosaccharomyces Comparative Genome Project project is part of the Broad Institute Fungal Genome Initiative. Its goal was to sequence, annotate and analyze the genomes and transcriptomes of Schizosaccharomyces japonicus, Schizosaccharomyces octosporus and Schizosaccharomyces cryophilus. The primary collaborator for this project was Nick Rhind at the University of Massachusetts, Worcester, Medical School.
In fission yeast both DNA polymerase alpha (pol alpha) and delta (pol delta) are required for DNA chromosomal replication. Here we demonstrate that Schizosaccharomyces pombe cdc20+ encodes the catalytic subunit of DNA polymerase epsilon (pol epsilon) and that this enzyme is also required for DNA replication. Following a shift to the restrictive temperature, cdc20 temperature-sensitive mutant cells block at the onset of DNA replication, suggesting that cdc20+ is required early in S phase very near to the initiation step. In the budding yeast Saccharomyces cerevisiae, it has been reported that in addition to its proposed role in chromosomal replication, DNA pol epsilon (encoded by POL2) also functions directly as an S phase checkpoint sensor [Navas, T. A., Zhou, Z. & Elledge, S. J. (1995) Cell 80, 29-39]. We have investigated whether cdc20+ is required for the checkpoint control operating in fission yeast, and our data indicate that pol epsilon does not have a role as a checkpoint sensor ...
Yeast strains and cell culture: Schizosaccharomyces pombe strains used were a haploid strain (h− leu1-32 ura4-D18 ade6-m216), a diploid strain (h−/h+ leu1-32/leu1-32 ura4-D18/ura4-D18 ade6-m210/ade6-m216), and a mutant haploid strain pim1-d1ts (h− leu1-32 ura4-D18 pim1-d1ts; Sazer and Nurse 1994), all of which are derived from strain 972 (Leupold 1970). Cell culture conditions, media composition, and genetic analyses have been described previously (Morenoet al. 1991).. nmt1 promoter regulation: Gene expression under the control of the nmt1 promoter (Maundrell 1990) in pREP3X or pREP41X (Forsburg 1993) was repressed by the inclusion of 5 μg/ml thiamine in the Edinburgh Minimal Media (EMM; Morenoet al. 1991). To derepress expression, cells were washed three times with thiamine-free EMM and grown in fresh thiamine-free EMM.. cDNA library screen and DNA manipulations: An S. pombe cDNA library (a gift from Bruce Edgar and Chris Norbury) in the pREP3X vector (Forsburg 1993) was transformed into ...
In this study, we created a fission yeast insertion mutant library in which all mutants were tagged with unique barcode sequences and stored as two readily available selection platforms. The 384-well mutant arrays allow genetic screens on individual mutants and can be extended to genetic approaches such as synthetic genetic array (SGA) [45, 46]. These mutant arrays have been used to identify mutants with four distinct phenotypes (Table 2) as well as strains that are hyper-sensitive to cancer chemotherapeutics camptothecin and bleomycin (Hale and Runge, unpublished data). In addition to 384-well mutant arrays, mutant pools of 1800 mutants are available for parallel analysis.. The insertion mutagenesis used in this study relied on random non-homologous recombination, where a vast majority of transformants have unstable, circularized vector DNA and only a small portion have stable insertions. To facilitate the collection of stable insertion mutants, we included low-dose 5-FOA in our initial ...
Syntaxin is a component of t-soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE), which is responsible for docking membrane vesicles at the target membrane and is highly conserved among eukaryotes. In the fission yeast Schizosaccharomyces pombe, the psy1(+) gene encoding a …
NUCLEOCYTOPLASMIC transport is a process specific to eukaryotes in which the chromosomes are physically separated from the cytoplasm by the nuclear envelope (NE). In all eukaryotes, the receptor-mediated transport of nuclear proteins across the NE from their site of synthesis in the cytoplasm is essential for all nuclear processes. The precise tissue-specific and temporal regulation of nuclear protein import is also critical in the regulation of cell cycle progression and in developmental and signal transduction pathways (reviewed in Kaffman and OShea 1999).. Proteins are targeted to the nucleus by an NLS (nuclear localization signal). There are two types of classical NLSs, both of which must bind to an importin-α adaptor for transport to the nucleus: the mono-partite NLS that consists of 4 or more basic amino acids preceded by a helix-breaking residue and the bipartite NLS that has two short stretches of basic amino acids separated by a 9- to 12-amino-acid spacer (reviewed in Izaurralde and ...
For the survival of both the parent and the progeny, it is imperative that the process of their physical division (cytokinesis) be precisely coordinated with progression through the mitotic cell cycle. Recent studies in the budding yeast Saccharomyces cerevisiae and the fission yeast Schizosaccharomyces pombe are beginning to unravel the nature of the links between cytokinesis and the nuclear division cycle. The cyclin-dependent kinases and a novel surveillance mechanism that monitors cytokinesis and/or morphogenesis appear to play important regulatory roles in forging these links. It is becoming increasingly clear that the inactivation of the mitosis-promoting cyclin-dependent kinase, which marks the completion of the nuclear division cycle, is essential for actomyosin ring constriction and division septum assembly in both yeasts. Additionally, the spindle pole bodies are emerging as important transient locale for proteins that might play a key role in coupling the completion of mitosis to the ...
The fission yeast Schizosaccharomyces pombe divides by medial fission through the use of an actomyosin contractile ring. Precisely at the end of anaphase, the ring begins to constrict and the septum forms. Proper coordination of cell division with mitosis is crucial to ensure proper segregation of chromosomes to daughter cells. The Sid2p kinase is one of several proteins that function as part of a novel signaling pathway required for initiation of medial ring constriction and septation. Here, we show that Sid2p is a component of the spindle pole body at all stages of the cell cycle and localizes transiently to the cell division site during medial ring constriction and septation. A medial ring and an intact microtubule cytoskeleton are required for the localization of Sid2p to the division site. We have established an in vitro assay for measuring Sid2p kinase activity, and found that Sid2p kinase activity peaks during medial ring constriction and septation. Both Sid2p localization to the division site
To decrypt the regulatory code of the genome, sequence elements must be defined that determine the kinetics of RNA metabolism and thus gene expression. Here, we attempt such decryption in an eukaryotic model organism, the fission yeast S. pombe. We first derive an improved genome annotation that redefines borders of 36% of expressed mRNAs and adds 487 non-coding RNAs (ncRNAs). We then combine RNA labeling invivo with mathematical modeling to obtain rates of RNA synthesis and degradation for 5,484 expressed RNAs and splicing rates for4,958 introns. We identify functional sequence elements inDNA and RNA that control RNA metabolic rates and quantifythecontributions of individual nucleotides to RNA synthesis,splicing, and degradation. Our approach reveals distinct kineticsof mRNA and ncRNA metabolism, separates antisense regulation by transcription interference from RNA interference, and provides a general tool for studying the regulatory code of genomes. ...
The fission yeast Schizosaccharomyces pombe is a useful model for analysing DNA replication as genetic methods to allow conditional inactivation of relevant proteins can provide important information about S-phase execution. A number of strategies are available to allow regulation of protein level or activity but there are disadvantages specific to each method and this may have limitations for particular proteins or experiments. We have investigated the utility of the inducible hormone-binding domain (HBD) system, which has been described in other organisms but little used in fission yeast, for the creation of conditional-lethal replication mutants. In this method, proteins are tagged with HBD and can be regulated with β-estradiol. In this article, we describe the application of this method in fission yeast, specifically with regard to analysis of the function of GINS, an essential component of the eukaryotic replicative helicase, the CMG complex.
Elevated levels of certain membrane proteins, including the sterol biosynthetic enzyme HMG-CoA reductase, induce proliferation of the endoplasmic reticulum. When the amounts of these proteins return to basal levels, the proliferated membranes are degraded, but the molecular details of this degradation remain unknown. We have examined the degradation of HMG-CoA reductase-induced membranes in the fission yeast, Schizosaccharomyces pombe. In this yeast, increased levels of the Saccharomyces cerevisiae HMG-CoA reductase isozyme encoded by HMG1 induced several types of membranes, including karmellae, which formed a cap of stacked membranes that partially surrounded the nucleus. When expression of HMG1 was repressed, the karmellae detached from the nucleus and formed concentric, multilayered membrane whorls that were then degraded. During the degradation process, CDCFDA-stained compartments distinct from preexisting vacuoles formed within the interior of the whorls. In addition to these compartments, ...
In the fission yeast Schizosaccharomyces pombe, the onset of septum formation is induced by a signal transduction network involving several protein kinases and a GTPase switch. One of the roles of the spg1p GTPase is to localise the cdc7p protein kinase to the poles of the mitotic spindle, from where the onset of septation is thought to be signalled at the end of mitosis. Immunofluorescence studies have shown that cdc7p is located on both spindle pole bodies early in mitosis, but only on one during the later stages of anaphase. This is mediated by inactivation of spg1p on one pole before the other. The GAP for spg1p is a complex of two proteins, cdc16p and byr4p. Localisation of cdc16p and byr4p by indirect immunofluorescence during the mitotic cell cycle showed that both proteins are present on the spindle pole body in interphase cells. During mitosis, byr4p is seen first on both poles of the spindle, then on only one. This occurs prior to cdc7p becoming asymmetric. In contrast, the signal due ...
The cdc2+ gene function plays a central role in the control of the mitotic cell cycle of the fission yeast Schizosaccharomyces pombe. Recessive temperature-sensitive mutations in the cdc2 gene cause cell cycle arrest when shifted to the restrictive temperature, while a second class of mutations within the cdc2 gene causes a premature advancement into mitosis. Previously the cdc2+ gene has been cloned and has been shown to encode a 34 kDa phosphoprotein with in vitro protein kinase activity. Here we describe the cloning of 11 mutant alleles of the cdc2 gene using two simple methods, one of which is presented here for the first time. We have sequenced these alleles and find a variety of single amino acid substitutions mapping throughout the cdc2 protein. Analysis of these mutations has identified a number of regions within the cdc2 protein that are important for cdc2+ activity and regulation. These include regions which may be involved in the interaction of the cdc2+ gene product with the proteins ...
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Inactivating a specific protein in vivo can yield important information about its function. One strategy previously developed in Saccharomyces cerevisiae by the Varshavsky group involves fusing a degron, derived from mouse dihydrofolate reductase, to the N-terminus of the target protein, which thereby confers temperature-sensitive degradation at the restrictive temperature. We describe here the application of this technique in the fission yeast, Schizosaccharomyces pombe.
Eukaryotic cells have developed elaborate regulatory mechanisms to ensure that DNA replication is restricted to S phase and occurs just once per cell cycle. An important component of this regulation is the coordination of multiple origins of replication. Data from many systems have provided a model of the initiation of DNA synthesis in which several multiprotein complexes interact with discrete replication origins in a specific temporal pattern to regulate entry into S phase (24, 26, 32). Two protein kinase complexes are required to activate the replication origins: cyclin-cyclin-dependent kinase (CDK), which acts both positively and negatively to control origin function (21,22), and the product of the hsk1 + (also called CDC7) gene complex.. Schizosaccharomyces pombe hsk1 + is a member of the conserved family of CDC7 protein kinases (23, 37). Thehsk1 + gene was originally cloned by its sequence homology to budding yeast CDC7 and is essential for viability (36). Spores with hsk1 +deleted are ...
Eukaryotic cells have developed elaborate regulatory mechanisms to ensure that DNA replication is restricted to S phase and occurs just once per cell cycle. An important component of this regulation is the coordination of multiple origins of replication. Data from many systems have provided a model of the initiation of DNA synthesis in which several multiprotein complexes interact with discrete replication origins in a specific temporal pattern to regulate entry into S phase (24, 26, 32). Two protein kinase complexes are required to activate the replication origins: cyclin-cyclin-dependent kinase (CDK), which acts both positively and negatively to control origin function (21,22), and the product of the hsk1 + (also called CDC7) gene complex.. Schizosaccharomyces pombe hsk1 + is a member of the conserved family of CDC7 protein kinases (23, 37). Thehsk1 + gene was originally cloned by its sequence homology to budding yeast CDC7 and is essential for viability (36). Spores with hsk1 +deleted are ...
In virtually all eukaryotes, mitosis starts after the completion of DNA synthesis. This orderly process is ensured by the checkpoint mechanism that blocks the onset of mitosis while DNA is being synthesized or is damaged. In the fission yeast Schizosaccharomyces pombe, this mechanism involves some r …
Reactive oxygen species (ROS) can damage cellular components leading to cell death, but paradoxically, ROS also play essential roles in metabolism and signalling in eukaryotic cells. Dysregulation of this balance is associated with a range of host diseases and cells have consequently evolved sophisticated signalling networks to sense, detoxify and adapt to changes in ROS levels. Hydrogen peroxide, for example, is reduced by thiol-peroxidases which in turn, can trigger the oxidation of thiol-dependent redox transcription factors. However, the relationship between hydrogen peroxide stimuli and the level of redox transcription factor activation has largely been described in qualitative terms. Because quantitative measures of the redox signal have been lacking, we tested whether three signalling parameters viz. the signalling time, duration and amplitude could be used to quantify the hydrogen peroxide-dependent redox signal in the Tpx1/Pap1 pathway in Schizosaccharomyces pombe. We found significant ...
Kohli, J., Hottinger, H., Munz, P., Strauss, A., Thuriaux, P. 1977. Genetic mapping in Schizosaccharomyces pombe by mitotic and meiotic analysis and induced haploidization. Genetics, 87, 471-489 ...
The Schizosaccharomyces pombe HIRA-like protein hip1 is required for the periodic expression of histone genes and contributes to the function of complex ...
Brown, William R.A. and Litti, Gianni and Rosa, Carlos and James, Steve and Roberts, Ian and Robert, Vincent and Jolly, Neil and Tang, Wen and Baumann, Peter and Green, Carter and Schlegel, Kristina and Young, Jonathan and Hirchaud, Fabienne and Leek, Spencer and Thomas, Geraint and Blomberg, Anders and Warringer, Jonas (2011) A geographically diverse collection of schizosaccharomyces pombe isolates shows limited phenotypic variation but extensive karyotypic diversity. G3, 1 (7). pp. 615-626. ISSN 2160-1836 ...
Rombouts, PMM, Gomez-Morilla, I, Grime, GW, Webb, RP, Cuenca, L, Rodriguez, R, Browton, M, Wardell, N, Underwood, B, Kirkby, NF et al and Kirkby, KJ. (2007) A microPIXE investigation of the interaction of cells of Schizosaccharomyces pombe with the culture medium In: 10th International Conference on Nuclear Microprobe Technology and Applications held in Conjunction with the 2nd International Workshop on Proton Beam Writing, 2006-07-09 - 2006-07-14, Singapore, SINGAPORE. Full text not available from this repository ...
ID AB009602; SV 1; linear; mRNA; STD; FUN; 561 BP. XX AC AB009602; XX DT 15-DEC-1997 (Rel. 53, Created) DT 14-APR-2005 (Rel. 83, Last updated, Version 2) XX DE Schizosaccharomyces pombe mRNA for MET1 homolog, partial cds. XX KW MET1 homolog. XX OS Schizosaccharomyces pombe (fission yeast) OC Eukaryota; Fungi; Dikarya; Ascomycota; Taphrinomycotina; OC Schizosaccharomycetes; Schizosaccharomycetales; Schizosaccharomycetaceae; OC Schizosaccharomyces. XX RN [1] RP 1-561 RA Kawamukai M.; RT ; RL Submitted (07-DEC-1997) to the EMBL/GenBank/DDBJ databases. RL Makoto Kawamukai, Shimane University, Life and Environmental Science; 1060 RL Nishikawatsu, Matsue, Shimane 690, Japan RL (E-mail:[email protected], Tel:0852-32-6587, Fax:0852-32-6499) XX RN [2] RP 1-561 RA Kawamukai M.; RT "S.pmbe MET1 homolog"; RL Unpublished. XX FH Key Location/Qualifiers FH FT source 1..561 FT /organism="Schizosaccharomyces pombe" FT /mol_type="mRNA" FT /clone_lib="pGAD GH" FT /db_xref="taxon:4896" FT CDS ,1..275 FT ...
In dividing cells, the assembly and contraction of the cytokinetic actomyosin ring (CAR) is precisely coordinated with spindle formation and chromosome segregation. Despite having a cell wall, the fission yeast Schizosaccharomyces pombe forms a CAR reminiscent of the structure responsible for the cleavage of cells with flexible boundaries. We used the myo2-gc fission yeast strain in which the chromosomal copy of the type II myosin gene, myo2(+), is fused to the gene encoding green fluorescent protein (GFP) to investigate the dynamics of Myo2 recruitment to the cytokinetic actomyosin ring in living cells. Analysis of CAR formation in relation to spindle pole body (SPB) and centromere separation enabled us to pinpoint the timing of Myo2 recruitment into a stable CAR structure to the onset of anaphase A. Depolymerisation of actin with latrunculin B did not affect the timing of Myo2 accumulation at the cell equator (although Myo2 no longer formed a ring), whereas depolymerisation of microtubules ...
Progression through the eukaryotic cell cycle is governed by cyclin-dependent kinases (CDKs) in conjunction with their cyclin partners (Morgan, 1997). (For nomenclature, Arabidopsis thaliana wild-type genes [in italics] and proteins [not italicized] use all uppercase letters, and mutants are in lowercase letters [in italics]. In fission yeast [Schizosaccharomyces pombe] and budding yeast [Saccharomyces cerevisiae], wild-type proteins are not italicized and in title case, with fission yeast having a postfix superscript "+" and budding yeast a postfix lowercase "p" indicating the protein nature. All other proteins are in title case except if stated otherwise in the National Center for Biotechnology Information [NCBI] library. Generalized terms appear not italicized and uppercase.) A key principle and the driving force of the cell cycle is the generation of alternating phases of high and low kinase activity (Nasmyth, 1996). At times of high CDK-cyclin activity, a number of target proteins become ...
Dr. Nurses research focuses on the molecular machineries that control cell division and cell shape. Using the fission yeast Schizosaccharomyces pombe as a model system, his laboratory studies the cell cycle and cell morphogenesis controls operative in eukaryotic cells. His major past contribution was the codiscovery of cyclin-dependent kinase (CDK) as the key regulator molecule controlling S phase and mitosis, findings that have had implications for understanding cell reproduction, cell growth, development, and cancer. Present work in the Nurse laboratory is in three areas: the cell cycle, cell form, and genomic studies. The lab is split on two sites, with the major activity located at the Francis Crick Institute in London, and a smaller group located at The Rockefeller University, which works mainly on combining chemical biology and genetics to investigate cell biology problems in fission yeast.. In collaboration with Tarun Kapoor, the Nurse lab works on the development and use of fission ...
TY - JOUR. T1 - Cell-cycle control linked to extracellular environment by MAP kinase pathway in fission yeast. AU - Shiozaki, Kazuhiro. AU - Russell, Paul. PY - 1995/12/14. Y1 - 1995/12/14. N2 - In fission yeast the onset of mitosis is brought about by Cdc2/Cdc13 kinase, which is inhibited by the Wee1/Mik1 tyrosine kinases and activated by Cdc25 tyrosine phosphatase. This control network integrates many signals, including those that monitor DNA replication, DNA damage and cell size. We report here that a fission yeast MAP kinase pathway links the cell-cycle G2/M control with changes in the extracellular environment that affect cell physiology. Fission yeast spc1- mutants have a G2 delay that is greatly exacerbated by growth in high osmolarity media and nutrient limitation. A lethal interaction of spc1 and cdc25 mutations shows that Spc1 promotes the onset of mitosis. Spc1 is a MAP kinase homologue that is activated by Wis1 kinase in response to osmotic stress and nutrient limitation. Spc1 is ...
Eukaryotic organisms use cell-cycle checkpoints to ensure that nuclear division is restrained while DNA is undergoing replication or repair. Recent studies of the fission yeast Schizosaccharomyces pombe have illuminated these checkpoint mechanisms. These investigations have connected checkpoint proteins with central elements of the mitotic-control machinery ...
Win, Thein Zaw; (2001) Characterisation of two Class V myosins in the fission yeast Schizosaccharomyces pombe. Doctoral thesis (Ph.D), UCL (University College London). Green open ...
Here we show that RNA polymerase II (RNAPII) transcription of ncRNAs is required for chromatin remodelling at the fission yeast Schizosaccharomyces pombe fbp1+ locus during transcriptional activation. The chromatin at fbp1+ is progressively converted to an open configuration, as several species of ncRNAs are transcribed through fbp1+. This is coupled with the translocation of RNAPII through the region upstream of the eventual fbp1+ transcriptional start site. Insertion of a transcription terminator into this upstream region abolishes both the cascade of transcription of ncRNAs and the progressive chromatin alteration. Our results demonstrate that transcription through the promoter region is required to make DNA sequences accessible to transcriptional activators and to RNAPII ...
To address these questions, we primarily study a eukaryotic model organism, the fission yeast Schizosaccharomyces pombe. These are simple rod-shaped cells that display a highly uniform size and rod-shape morphology. We seek to elucidate quantitative molecular and biomechanical mechanisms underlying the dynamic cellular processes responsible for morphogenesis of the cell. In our work, we use interdisciplinary approaches, combining the expertise and perspectives of cell biologists, geneticists, physicists, and engineers. We seek to develop new approaches to manipulate and assay processes in living cells, using microscopy, genetics, and micro-fabricated devices ...
It is well established that the kinase activity of the p34cdc2 cyclinB complex known as MPF regulates commitment to mitosis (Ohi and Gould, 1999). Once MPF has been activated, polo, aurora and NIMA‐related kinases (Nrks) control most of the physical events of mitosis and cytokinesis (Nigg, 2001).. In interphase, Wee1 and related protein kinases phosphorylate and inhibit the p34cdc2 catalytic subunit of MPF. This inhibitory phosphate is removed by the phosphatase Cdc25. The balance between Wee1‐ and Cdc25‐related activities controls mitotic commitment (Ohi and Gould, 1999). An initial trigger level of MPF promotes further activation of Cdc25 to drive commitment to mitosis (Hoffmann et al., 1993), so that the activity of the bulk of Cdc25 is actually dependent upon p34cdc2 activity (Kovelman and Russell, 1996). While direct phosphorylation of Cdc25 by MPF does contribute to positive feedback loop activation of Cdc25 (Izumi and Maller, 1993), the loop still exists in Xenopus extracts from ...
As a result of checkpoint activation, a signalling cascade is initiated and a number of complexes between the checkpoint components are formed. This leads to the inhibition of the Anaphase Promoting Complex (APC), which is the ubiquitin ligase responsible for targeting mitotic proteins: securing and cyclin B for degradation by the 26S proteasome. The complexes formed include the MCC, or Mitotic Checkpoint Complex, which in fission yeast (Schizosaccharomyces pombe) consists of Mad2, Mad3 checkpoint proteins together with the APC activator, Slp1 (the Cdc20 homologue). The MCC has been shown to bind and inhibit the APC in HeLa cells. In my PhD I focused on the interactions between the MCC and the APC, in particular on Mad3 protein. Mad3 is a conserved checkpoint component, homologous to human BubR1. It carries 2 putative KEN boxes, motifs, which typically target proteins for degradation (like D-boxes). We mutated both KEN boxes in S. pombe Mad3 and show that they are essential for Mad3 checkpoint ...
Bioneers exclusive Schizosaccharomyces pombe (S. pombe) Genome-wide Deletion Mutant Library is a powerful tool for large-scale genetic functional analysis, identification and verification research of drug targets and for integrated systems research of cell function. Co-developed by Bioneer and KRIBB in collaboration with Dr. Paul Nurse of the Cancer Research Center in UK, the S. pombe Genome-wide Deletion Mutant Library can be used for genetic and chemical screening such as drug target identification, gene expression profiling, and synthetic lethal profiling. S. pombe offers higher homology with mammalian cells and human genes than those of S. pombe. S. pombe Genome-wide Deletion Mutant Library targets every ORF (4,914 types) in the S. pombe genome through a targeted mutagenesis method. A total of 4,836 heterozygous diploid deletion mutants representing 98.4% of the organism genome and 3,400 haploid deletion mutants with 95.3% genome coverage are available. Since there are different tag ...
Link to Pubmed [PMID] - 24748152. PLoS ONE 2014;9(4):e95788. Rad52 is a key protein in homologous recombination (HR), a DNA repair pathway dedicated to double strand breaks and recovery of blocked or collapsed replication forks. Rad52 allows Rad51 loading on single strand DNA, an event required for strand invasion and D-loop formation. In addition, Rad52 functions also in Rad51 independent pathways because of its ability to promote single strand annealing (SSA) that leads to loss of genetic material and to promote D-loops formation that are cleaved by Mus81 endonuclease. We have previously reported that fission yeast Rad52 is phosphorylated in a Sty1 dependent manner upon oxidative stress and in cells where the early step of HR is impaired because of lack of Rad51. Here we show that Rad52 is also constitutively phosphorylated in mus81 null cells and that Sty1 partially impinges on such phosphorylation. As upon oxidative stress, the Rad52 phosphorylation in rad51 and mus81 null cells appears to ...
Research Assistant position, genome sequencing A graduate Research Assistant is required to perform and direct DNA sequencing as part of the EU-funded Schizosaccharomyces pombe genome sequencing project. Applicants should have experience of automated sequencing and/or computer-based DNA sequence assembly. The appointment is on the RA1B scale (salary range £14,317- £15,986 p.a., under review) and is for one year in the first instance, with the possibility of extension up to three years. For further information contact Dr Steve Aves: tel 01392 264675, fax 01392 264668, e-mail S.J.Aves at exeter.ac.uk. Applications (CV plus 2 referees and a covering letter indicating relevant experience) should be sent to Dr Steve Aves at the Department of Biological Sciences, University of Exeter, Perry Road, Exeter EX4 4QG by 24 January 1997, quoting reference number R239. **************************** Dr S J Aves Department of Biological Sciences University of Exeter Perry Road Exeter EX4 4QG UK Tel: +44 1392 ...
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ABSTRACT: Much is known about the genes and proteins controlling the cell cycle of fission yeast. Can these molecular components be spun together into a consistent mechanism that accounts for the observed behavior of growth and division in fission yeast cells? To answer this question, we propose a mechanism for the control system, convert it into a set of 14 differential and algebraic equations, study these equations by numerical simulation and bifurcation theory, and compare our results to the physiology of wild-type and mutant cells. In wild-type cells, progress through the cell cycle (G1--,S--,G2--,M) is related to cyclic progression around a hysteresis loop, driven by cell growth and chromosome alignment on the metaphase plate. However, the control system operates much differently in double-mutant cells, wee1(-) cdc25Delta, which are defective in progress through the latter half of the cell cycle (G2 and M phases). These cells exhibit "quantized" cycles (interdivision times clustering around ...
We are interested in understanding how gene expression is encoded in genomes, and how to leverage this knowledge to understand the basis of genetic diseases. To this end, we employ statistical modeling of omics data and work in close collaboration with experimentalists. I will provide an overview of recent studies from our lab, covering work on RNA metabolism in S. pombe [1] and on mRNA stability in S. cerevisiae [2], and discussing the implications of TT-seq, a novel protocol suited to study nascent transcriptomes in higher eukaryotes [3]. I will also report on a recent pilot study where we established RNA-sequencing as a powerful companion tool to genome sequencing for pinpointing molecular causes of rare genetic disorders [4]. The talk will end with a discussion on future directions in computational modeling of cis-regulatory elements.. References [1] Eser. et al, Determinants of RNA metabolism in the Schizosaccharomyces pombe genome, Molecular Systems Biology, 2016 [2] Cheng, et al. ...
Fission yeast cell division is initiated by the cdc2/cdc13-cyclin protein kinase which in its catalytically active state comprises the mitotic inducer. During interphase the cdc2/cyclin complex is assembled in an inactive state that requires cdc25+ gene function for M-phase activation. The cdc25+ product, a 76 kd phosphoprotein, is shown to oscillate in abundance during the cell cycle, reaching a peak at G2/M, and to be sensitive to nitrogen starvation. The level of cdc25 is subject to feedback regulation involving both cdc25 and cdc2.. ...
Catalytic domain of Cell division control protein 7-like Protein Serine/Threonine Kinases. Serine/threonine kinases (STKs), (Cdc7)-like subfamily, catalytic (c) domain. STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. The Cdc7-like subfamily is part of a larger superfamily that includes the catalytic domains of other protein STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase. Members of this subfamily include Schizosaccharomyces pombe Cdc7, Saccharomyces cerevisiae Cdc15, Arabidopsis thaliana mitogen-activated protein kinase (MAPK) kinase kinase (MAPKKK) epsilon, and related proteins. MAPKKKs phosphorylate and activate MAPK kinases (MAPKKs or MKKs or MAP2Ks), which in turn phosphorylate and activate MAPKs during signaling cascades that are important in mediating cellular responses to extracellular signals. Fission yeast Cdc7 is essential for cell ...
Cell, Cell Division, Cell Proliferation, Cells, Fission Yeast, Germ Cell, Heterochromatin, Kinases, Oncogenesis, Regulation, Schizosaccharomyces, Schizosaccharomyces Pombe, Yeast
A comprehensive formalism to calculate fission cross sections based on the extension of the optical model for fission is presented. It can be used for description of nuclear reactions on actinides featuring multi-humped fission barriers with partial absorption in the wells and direct transmission through discrete and continuum fission channels. The formalism describes the gross fluctuations observed in the fission probability due to vibrational resonances, and can be easily implemented in existing statistical reaction model codes. The extended optical model for fission is applied for neutron induced fission cross-section calculations on 234,235,238U and 239Pu targets. A triple-humped fission barrier is used for 234,235U(n,f), while a double-humped fission barrier is used for 238U(n,f) and 239Pu(n,f) reactions as predicted by theoretical barrier calculations. The impact of partial damping of class-II/III states, and of direct transmission through discrete and continuum fission channels, is shown ...
Acetaldehyde, Ethanol, Zinc, Copper, Genes, Iron, Alcohol Dehydrogenase, Dehydrogenase, Gene, Gene Expression, Repression, Schizosaccharomyces, Schizosaccharomyces Pombe, Cell, Growth, Ions, Life, Metals, Proteins, Transcription Factors