scholarly journals pkl1 +andklp2 +: Two Kinesins of the Kar3 Subfamily in Fission Yeast Perform Different Functions in Both Mitosis and Meiosis

2001 ◽  
Vol 12 (11) ◽  
pp. 3476-3488 ◽  
Author(s):  
Cynthia L. Troxell ◽  
Mark A. Sweezy ◽  
Robert R. West ◽  
Karen D. Reed ◽  
Bryan D. Carson ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Sexual Reproduction ◽  
Fission Yeast ◽  
Wild Type ◽  
Mitotic Chromosomes ◽  
Double Deletion ◽  
Early Anaphase ◽  
Spindle Disassembly ◽  
And Function ◽  
Mitosis And Meiosis

We have identified Klp2p, a new kinesin-like protein (KLP) of the KAR3 subfamily in fission yeast. The motor domain of this protein is 61% identical and 71% similar to Pkl1p, another fission yeast KAR3 protein, yet the two enzymes are different in behavior and function. Pkl1p is nuclear throughout the cell cycle, whereas Klp2p is cytoplasmic during interphase. During mitosis Klp2p enters the nucleus where it forms about six chromatin-associated dots. In metaphase-arrested cells these migrate back and forth across the nucleus. During early anaphase they segregate with the chromosomes into two sets of about three, fade, and are replaced by other dots that form on the spindle interzone. Neitherklp2 + norpkl1 + is essential, and the double deletion is also wild type for both vegetative and sexual reproduction. Each deletion rescues different alleles ofcut7 ts , a KLP that contributes to spindle formation and elongation. When either or both deletions are combined with a dynein deletion, vegetative growth is normal, but sexual reproduction fails: klp2Δ,dhc1-d1 in karyogamy, pkl1Δ,dhc1-d1 in multiple phases of meiosis, and the triple deletion in both. Deletion of Klp2p elongates a metaphase-arrested spindle, but pkl1Δshortens it. The anaphase spindle of klp2Δ becomes longer than the cell, leading it to curl around the cell's ends. Apparently, Klp2p promotes spindle disassembly and contributes to the behavior of mitotic chromosomes.

scholarly journals A fission yeast general translation factor reveals links between protein synthesis and cell cycle controls

2000 ◽  
Vol 113 (8) ◽  
pp. 1447-1458 ◽  
Author(s):  
B. Grallert ◽  
S.E. Kearsey ◽  
M. Lenhard ◽  
C.R. Carlson ◽  
P. Nurse ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Fission Yeast ◽  
Single Gene ◽  
Mitotic Cell ◽  
Anaphase Promoting Complex ◽  
Wild Type ◽  
Rna Helicases ◽  
Translation Factor ◽  
And Function ◽  
General Translation

In two independent screens we isolated fission yeast mutations with phenotypes suggesting defects in B-cyclin function or expression. These mutations define a single gene which we call ded1. We show that ded1 encodes a general translation factor that is related in sequence and function to RNA helicases required for translation in other species. Levels of the B-cyclins Cig2 and Cdc13 are dramatically reduced upon inactivation of Ded1, and this reduction is independent of degradation by the anaphase promoting complex. When a ded1 mutant is grown under semi-restrictive conditions, the translation of Cig2 (and to a lesser extent Cdc13), is impaired relative to other proteins. We show that B-cyclin translation is specifically inhibited upon nitrogen starvation of wild-type cells, when B-cyclin/Cdc2 inactivation is a prerequisite for G(1) arrest and subsequent mating. Our data suggest that translational inhibition of B-cyclin expression represents a third mechanism, in addition to cyclin degradation and Rum1 inhibition, that contributes to Cdc2 inactivation as cells exit from the mitotic cell cycle and prepare for meiosis.

Polypeptide synthesis in cell cycle mutants of fission yeast

1981 ◽  
Vol 51 (1) ◽  
pp. 203-217
Author(s):  
D.P. Dickinson
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Fission Yeast ◽  
Gel Electrophoresis ◽  
Mutant Cell ◽  
Wild Type ◽  
Unsuccessful Attempt ◽  
Dependent Sequence ◽  
Polypeptide Synthesis ◽  
Cellular Components

The cell cycle of a growing cel is characterized by 3 main periodic events: DNA synthesis mitosis and cell division. These events generally lie in a dependent sequence, in which one event cannot occur unless preceding events have occurred. The existence of dependent sequences of events raises the possibility that at least some of the gene products involved in the events are synthesized in a dependent sequence parallel to the observable events. To test this hypothesis, the patterns of polypeptide synthesis were investigated in 2 types of cell cycle mutant of the fission yeast Schizosaccharomyces pombe: temperature-sensitive cell cycle (ts cdc) mutants. which become blocked in cell cycle progress at the restrictive temperature; and wee I mutants, which are defective in size control over nuclear division, and which divide at a small size. Cells of mutants and wild-type cells were labelled with [35S[sulphate under conditions designed to maximize any differences between the labelling patterns of wild-type and mutant cell polypeptides. The polypeptides were then separated by O'Farrell 2-dimensional gel electrophoresis, and the patterns compared. Although both types of mutation affect cell cycle control, and cause a considerable alteration in the relative proportions of cellular components, an examination of over 700 polypeptides detected on gels revealed no qualitative differences between wild-type and mutant cell polypeptides. These results suggest that a large majority of the more abundant polypeptides in the growing cell are synthesized independently of cell cycle controls directly related to DNA synthesis and division, and that the synthesis of these polypeptides can occur in the absence of normal progress through the cell cycle. Dependent sequences of gene expression do not appear to make a significant contribution to total polypeptide synthesis during the cell cycle, or to the occurrence of periodic cell cycle events such as mitosis. It is suggested that such cell cycle events may result largely through the reorganization of existing cellular components, rather than by the synthesis of new ones. An unsuccessful attempt was made to detect the wee I gene product on gels by surveying a range of mutants for changes in an individual spot. The limitations of gel electrophoresis for this type of survey, and other cell cycle experiments, are discussed.

scholarly journals Mid2p stabilizes septin rings during cytokinesis in fission yeast

2003 ◽  
Vol 160 (7) ◽  
pp. 1083-1092 ◽  
Author(s):  
Ana Berlin ◽  
Anne Paoletti ◽  
Fred Chang
Keyword(s):  
Fission Yeast ◽  
Cell Separation ◽  
Sequence Similarity ◽  
Ring Closure ◽  
Pleckstrin Homology Domain ◽  
Wild Type ◽  
Contractile Ring ◽  
Single Ring ◽  
And Function ◽  
Cell Cell

Septins are filament-forming proteins with a conserved role in cytokinesis. In the fission yeast Schizosaccharomyces pombe, septin rings appear to be involved primarily in cell–cell separation, a late stage in cytokinesis. Here, we identified a protein Mid2p on the basis of its sequence similarity to S. pombe Mid1p, Saccharomyces cerevisiae Bud4p, and Candida albicans Int1p. Like septin mutants, mid2Δ mutants had delays in cell–cell separation. mid2Δ mutants were defective in septin organization but not contractile ring closure or septum formation. In wild-type cells, septins assembled first during mitosis in a single ring and during septation developed into double rings that did not contract. In mid2Δ cells, septins initially assembled in a single ring but during septation appeared in the cleavage furrow, forming a washer or disc structure. FRAP studies showed that septins are stable in wild-type cells but exchange 30-fold more rapidly in mid2Δ cells. Mid2p colocalized with septins and required septins for its localization. A COOH-terminal pleckstrin homology domain of Mid2p was required for its localization and function. No genetic interactions were found between mid2 and the related gene mid1. Thus, these studies identify a new factor responsible for the proper stability and function of septins during cytokinesis.

scholarly journals A mitotic role for a novel fission yeast protein kinase dsk1 with cell cycle stage dependent phosphorylation and localization.

1993 ◽  
Vol 4 (3) ◽  
pp. 247-260 ◽  
Author(s):  
M Takeuchi ◽  
M Yanagida
Keyword(s):  
Cell Cycle ◽  
Protein Kinase ◽  
Fission Yeast ◽  
Cell Cycle Progression ◽  
Kinase Activity ◽  
Specific Protein ◽  
Wild Type ◽  
Mobility Shift ◽  
Multicopy Suppressor ◽  
Phosphorylation Pattern

The fission yeast dsk1+ gene, a multicopy suppressor for cold-sensitive dis1 mutants, encodes a novel 61-kd protein kinase. It is a phosphoprotein, and phosphoserine is the major phosphorylated amino acid. Hyperphosphorylation of dsk1 causes a mobility shift, resulting in two dsk1-specific protein bands. The phosphorylation pattern is strikingly altered when cell cycle progression is delayed or arrested. The slowly migrating phosphorylated form is prominent in mitotically arrested cells, and the fast migrating form is enriched in interphase-arrested cells. dsk1 is a protein kinase. It auto-phosphorylates as well as phosphorylates myelin basic protein (MBP). Phosphotyrosine as well as phosphoserine/threonine were found in autophosphorylation, but no tyrosine phosphorylation occurs when MBP was used as the substrate. The dsk1 immunoprecipitates from mitotically arrested cells have a several-fold higher kinase activity than that from wild type. The haploid gene disruptant is viable, indicating that the dsk1+ gene is non-essential for viability. High dosage of dsk1+, however, strongly delays the G2/M progression. Immunofluorescence microscopy using anti-dsk1 antibody shows that localization pattern of dsk1 protein strikingly alters depending on cell cycle stages. In G2-arrested cells, dsk1 locates in the cytoplasm, whereas in mitotically arrested cells, nuclear stain is intense. In wild-type cells, nuclear stain is seen only in mitotic cells. Hence dsk1 protein may play an important role in mitotic control by altering cellular location, degree of phosphorylation and kinase activity. We discuss possible roles of dsk1 kinase as an add-on regulator in mitosis.

Interaction between the Cig1 and Cig2 B-type cyclins in the fission yeast cell cycle

1994 ◽  
Vol 14 (1) ◽  
pp. 768-776
Author(s):  
T Connolly ◽  
D Beach
Keyword(s):  
Cell Cycle ◽  
Fission Yeast ◽  
Null Allele ◽  
Wild Type Strain ◽  
Periodic Oscillation ◽  
S Phase ◽  
Wild Type ◽  
Nuclear Separation ◽  
The Relationship

In this report, we describe the cloning and characterization of a B-type cyclin, Cig2 from the fission yeast Schizosaccharomyces pombe. The cig2 gene encodes a 45-kDa protein that is most similar to a previously identified B-type cyclin in S. pombe, Cdc13. Deletion of cig2 had no observable effect on cell viability or progression through the cell cycle. Strains carrying the cig2 null allele do, however, exhibit an enhanced ability to undergo conjugation relative to a wild-type strain. The cig2 transcript was found to undergo periodic oscillation during the cell cycle, peaking at the G1/S-phase boundary. We have investigated the relationship between Cig2 and the other B-type cyclins, Cig1 and Cdc13, in the fission yeast. We found that cells carrying disruptions of both the cig1 and cig2 genes contain multiple nuclei with a 1C DNA content, suggesting that they are delayed in progression through the G1 phase of the cell cycle. The phenotype of this double mutant suggests that there is a delay in septum formation, possibly as a result of defective nuclear separation.

Fission yeast Nda1 and Nda4, MCM homologs required for DNA replication, are constitutive nuclear proteins

1996 ◽  
Vol 109 (2) ◽  
pp. 319-326 ◽  
Author(s):  
N. Okishio ◽  
Y. Adachi ◽  
M. Yanagida
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Fission Yeast ◽  
Budding Yeast ◽  
Affinity Column ◽  
Wild Type ◽  
M Phase ◽  
A Cell ◽  
Mcm Proteins ◽  
Cycle Dependent

The nda1+ and nda4+ genes of the fission yeast Schizosaccharomyces pombe encode proteins similar to budding yeast MCM2 and MCM5/CDC46, respectively, which are required for the early stages of DNA replication. The budding yeast Mcm proteins display cell-cycle dependent localization. They are present in the nucleus specifically from late M phase until the beginning of S phase, so that they were suggested to be components of a replication licensing factor, a positive factor for the onset of replication, which is thought to be inactivated after use, thus restricting replication to only once in a cell cycle. In the present study, we raised antibodies against Nda1 or Nda4 and identified 115 kDa and 80 kDa proteins, respectively. Their immunolocalization was examined in wild-type cells and in various cell-cycle mutants. Both Nda1 and Nda4 proteins remained primarily in the nucleus throughout the cell cycle. In mutants arrested in G1, S, and G2 phases, these proteins were also enriched in the nucleus. These results indicate that the dramatic change in subcellular localization as seen in budding yeast is not essential in fission yeast for the functions of Nda1 and Nda4 proteins to be executed. The histidine-tagged nda1+ gene was constructed and integrated into the chromosome to replace the wild-type nda1+ gene. The resulting His-tagged Nda1 protein was adsorbed to the Ni-affinity column, and co-eluted with the untagged Nda4 protein, suggesting that they formed a complex.

scholarly journals Interaction between the Cig1 and Cig2 B-type cyclins in the fission yeast cell cycle.

1994 ◽  
Vol 14 (1) ◽  
pp. 768-776 ◽  
Author(s):  
T Connolly ◽  
D Beach
Keyword(s):  
Cell Cycle ◽  
Fission Yeast ◽  
Null Allele ◽  
Wild Type Strain ◽  
Periodic Oscillation ◽  
S Phase ◽  
Wild Type ◽  
Nuclear Separation ◽  
The Relationship

In this report, we describe the cloning and characterization of a B-type cyclin, Cig2 from the fission yeast Schizosaccharomyces pombe. The cig2 gene encodes a 45-kDa protein that is most similar to a previously identified B-type cyclin in S. pombe, Cdc13. Deletion of cig2 had no observable effect on cell viability or progression through the cell cycle. Strains carrying the cig2 null allele do, however, exhibit an enhanced ability to undergo conjugation relative to a wild-type strain. The cig2 transcript was found to undergo periodic oscillation during the cell cycle, peaking at the G1/S-phase boundary. We have investigated the relationship between Cig2 and the other B-type cyclins, Cig1 and Cdc13, in the fission yeast. We found that cells carrying disruptions of both the cig1 and cig2 genes contain multiple nuclei with a 1C DNA content, suggesting that they are delayed in progression through the G1 phase of the cell cycle. The phenotype of this double mutant suggests that there is a delay in septum formation, possibly as a result of defective nuclear separation.

scholarly journals Two Related Kinesins,klp5+andklp6+, Foster Microtubule Disassembly and Are Required for Meiosis in Fission Yeast

2001 ◽  
Vol 12 (12) ◽  
pp. 3919-3932 ◽  
Author(s):  
Robert R. West ◽  
Terra Malmstrom ◽  
Cynthia L. Troxell ◽  
J. Richard McIntosh
Keyword(s):  
Cell Cycle ◽  
Fission Yeast ◽  
Amino Terminal ◽  
Cellular Processes ◽  
Cycle Arrest ◽  
Microtubule Motor ◽  
Cytoplasmic Microtubules ◽  
High Concentrations ◽  
Kinesin Superfamily ◽  
Mitosis And Meiosis

The kinesin superfamily of microtubule motor proteins is important in many cellular processes, including mitosis and meiosis, vesicle transport, and the establishment and maintenance of cell polarity. We have characterized two related kinesins in fission yeast,klp5+andklp6+, that are amino-terminal motors of the KIP3 subfamily. Analysis of null mutants demonstrates that neither klp5+norklp6+, individually or together, is essential for vegetative growth, although these mutants have altered microtubule behavior. klp5Δ and klp6Δ are resistant to high concentrations of the microtubule poison thiabendazole and have abnormally long cytoplasmic microtubules that can curl around the ends of the cell. This phenotype is greatly enhanced in the cell cycle mutant cdc25–22, leading to a bent, asymmetric cell morphology as cells elongate during cell cycle arrest. Klp5p-GFP and Klp6p-GFP both localize to cytoplasmic microtubules throughout the cell cycle and to spindles in mitosis, but their localizations are not interdependent. During the meiotic phase of the life cycle, both of these kinesins are essential. Spore viability is low in homozygous crosses of either null mutant. Heterozygous crosses of klp5Δ with klp6Δ have an intermediate viability, suggesting cooperation between these proteins in meiosis.

scholarly journals Histone H3 Tails Containing Dimethylated Lysine and Adjacent Phosphorylated Serine Modifications Adopt a Specific Conformation during Mitosis and Meiosis

2008 ◽  
Vol 28 (5) ◽  
pp. 1739-1754 ◽  
Author(s):  
Adrien Eberlin ◽  
Cédric Grauffel ◽  
Mustapha Oulad-Abdelghani ◽  
Flavie Robert ◽  
Maria-Elena Torres-Padilla ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Posttranslational Modifications ◽  
Chromatin Condensation ◽  
Histone H3 ◽  
Early Prophase ◽  
Chromatin Conformation ◽  
Early Anaphase ◽  
Mitosis And Meiosis ◽  
Tail Bound

ABSTRACT Condensation of chromatin, mediated in part by posttranslational modifications of histones, is essential for cell division during mitosis. Histone H3 tails are dimethylated on lysine (Kme2) and become phosphorylated on serine (Sp) residues during mitosis. We have explored the possibility that these double modifications are involved in the establishment of H3 tail conformations during the cell cycle. Here we describe a specific chromatin conformation occurring at Kme2 and adjacently phosphorylated S of H3 tails upon formation of a hydrogen bond. This conformation appears exclusively between early prophase and early anaphase of the mitosis, when chromatin condensation is highest. Moreover, we observed that the conformed H3Kme2Sp tail is present at the diplotene and metaphase stages in spermatocytes and oocytes. Our data together with results obtained by cryoelectron microscopy suggest that the conformation of Kme2Sp-modified H3 tails changes during mitosis and meiosis. This is supported by biostructural modeling of a modified histone H3 tail bound by an antibody, indicating that Kme2Sp-modified H3 tails can adopt at least two different conformations. Thus, the H3K9me2S10p and the H3K27me2S28p sites are involved in the acquisition of specific chromatin conformations during chromatin condensation for cell division.

scholarly journals The effect of CO2 on the timing of cell cycle events in fission yeast Schizosaccharomyces pombe

1988 ◽  
Vol 89 (3) ◽  
pp. 433-439
Author(s):  
B. NOVÁK ◽  
J. HALBAUER ◽  
E. LÁSZLÓ
Keyword(s):  
Cell Cycle ◽  
Growth Rate ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Co2 Production ◽  
Complete Medium ◽  
Co2 Removal ◽  
Wild Type ◽  
In The Wild ◽  
G2 Phase

The effect of CO2 removal on the cell cycle phases of Schizosaccharomyces pombe has been examinedin minimal, aspartate-containing and complete medium. The removal of CO2 shortened the G2 phase of the cell cycle and arrested the cells in G1 phase in minimal medium. The G1 block caused by CO2 deprivation was demonstrated by transition-point and flow-cytometry analyses. The slow-down of anapleurotic CO2 fixation might be responsible for this effect, as aspartic acid could abolish the G1 block. The shortening of G2 phase in the wild-type cells was observed in every medium irrespective of whether the growth rate was changed or not. The experiments in which growth rate was not changed by CO2 shift-down suggest that this CO2 effect can be independent from its action on CO2-fixing steps in metabolism. Therefore we propose that CO2 inhibits mitosis infission yeast and we explain the proportionality between growth rate and cell size at mitosis found by Fantes & Nurse by this CO2 inhibition. The larger CO2 production in fast-growing cells leads to a higher CO2 concentration, which could exerta stronger inhibition of mitosis. A wee mutant, which has lost its mitotic size control, also shows the G1 block after CO2 deprivation, but its mitosis is insensitive to CO2. Comparing the respiration of wee and wild-type cells we conclude that CO2 inhibits the citric acid cycle in the wild type. The consequence of these results in the regulation of fission yeast cell cycle is discussed.

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