scholarly journals Isolation and characterization of the fission yeast protein phosphatase gene ppe1+ involved in cell shape control and mitosis.

1993 ◽  
Vol 4 (3) ◽  
pp. 303-313 ◽  
Author(s):  
M Shimanuki ◽  
N Kinoshita ◽  
H Ohkura ◽  
T Yoshida ◽  
T Toda ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Shape Control ◽  
Budding Yeast ◽  
Suppressor Gene ◽  
Predicted Amino Acid Sequence ◽  
Permissive Temperature ◽  
Multicopy Suppressor ◽  
Isolation And Characterization ◽  
Cold Sensitive ◽  
Cell Shape Control

We isolated a fission yeast putative protein serine/threonine phosphatase gene designated ppe1+ by hybridization. The predicted amino acid sequence is similar to those of the fission yeast ppa2 (53% identity) and dis2 (39%) phosphatases, and highly similar to those of the budding yeast SIT4 (72%), Drosophila PPV (68%) and rabbit PPX (61%) phosphatases. Antibodies against ppe1 protein identified a 37-kd polypeptide in fission yeast. A gene disruption (designated delta ppe1) caused cold-sensitive lethality and short, pear-shaped cells. These phenotypes were fully suppressed by a plasmid carrying ppe1+. Three classes of multicopy suppressor genes for delta ppe1 were identified as follows: 1) ppa1+ and ppa2+ encoding type 2A-like phosphatases, 2) mitotically essential dis3+ similar to the budding yeast SSD1/SRK1, a suppressor for sit4, and 3) pck1+ coding for a protein kinase C-like kinase. Consistently, the budding yeast SIT4 gene was also a multicopy suppressor for delta ppe1. Phosphatase ppe1 may play a role in cell morphogenesis and mitosis by either regulating or being regulated by these multicopy suppressor gene products. Consistent with this hypothesis, double mutants ppe1-ppa2 and ppe1-pck1 are lethal at the permissive temperature.

The novel human protein serine/threonine phosphatase 6 is a functional homologue of budding yeast Sit4p and fission yeast ppe1, which are involved in cell cycle regulation

1996 ◽  
Vol 109 (12) ◽  
pp. 2865-2874 ◽  
Author(s):  
H. Bastians ◽  
H. Ponstingl
Keyword(s):  
Cell Cycle ◽  
Fission Yeast ◽  
Shape Control ◽  
Cell Cycle Regulation ◽  
Budding Yeast ◽  
Mitotic Checkpoint ◽  
Human Protein ◽  
Predicted Amino Acid Sequence ◽  
Temperature Sensitive ◽  
Cycle Regulation

We identified a novel human protein serine/threonine phosphatase cDNA, designated protein phosphatase 6 (PP6) by using a homology-based polymerase chain reaction. The predicted amino acid sequence indicates a 35 kDa protein showing high homology to other protein phosphatases including human PP2A (57%), human PP4 (59%), rat PPV (98%), Drosophila PPV (74%), Schizosaccharomyces pombe ppe1 (68%) and Saccharomyces cerevisiae Sit4p (61%). In human cells, three forms of PP6 mRNA were found with highest levels of expression in testis, heart and skeletal muscle. The PP6 protein was detected in lysates of human heart muscle and in bull testis. Complementation studies using a temperature sensitive mutant strain of S. cerevisiae SIT4, which is required for the G1 to S transition of the cell cycle, showed that PP6 can rescue the mutant growth arrest. In addition, a loss of function mutant of S. pombe ppe1, described as a gene interacting with the pim1/spi1 mitotic checkpoint and involved in cell shape control, can be complemented by expression of human PP6. These data indicate that human PP6 is a functional homologue of budding yeast Sit4p and fission yeast ppe1, implying a function of PP6 in cell cycle regulation.

scholarly journals Fission yeast genes nda1+ and nda4+, mutations of which lead to S-phase block, chromatin alteration and Ca2+ suppression, are members of the CDC46/MCM2 family.

1993 ◽  
Vol 4 (10) ◽  
pp. 1003-1015 ◽  
Author(s):  
S Miyake ◽  
N Okishio ◽  
I Samejima ◽  
Y Hiraoka ◽  
T Toda ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Positive Role ◽  
A Cell ◽  
Cold Sensitive ◽  
Single Nucleus ◽  
Yeast Genes ◽  
Cell Cycle Block ◽  
Mutant Cells

Fission yeast cold-sensitive mutants nda1-376 and nda4-108 display a cell cycle block phenotype at the restrictive temperature (cell elongation with the single nucleus) accompanied by an alteration in the nuclear chromatin region. DNA content analysis shows that the onset of DNA synthesis is blocked or greatly delayed in both mutant cells, the block being reversible in nda4-108. Upon release to the permissive temperature, nda4-108 cells resumed replicating DNA, followed by mitosis and cytokinesis. The nda4 phenotype was partly rescued by the addition of Ca2+ to the medium; Ca2+ plays a positive role in the nda4+ function. The predicted protein sequences of nda1+ and nda4+ isolated by complementation are similar to each other and also, respectively, to those of the budding yeast, MCM2 and CDC46, both of which are members of the gene family required for the initiation of DNA replication. The central domains of these proteins are conserved, whereas the NH2- and COOH- domains are distinct. Results of the disruption of the nda1+ and nda4+ genes demonstrates that they are essential for viability.

scholarly journals Bypassing anaphase by fission yeast cut9 mutation: requirement of cut9+ to initiate anaphase.

1994 ◽  
Vol 127 (6) ◽  
pp. 1655-1670 ◽  
Author(s):  
I Samejima ◽  
M Yanagida
Keyword(s):  
Amino Acid ◽  
Fission Yeast ◽  
Budding Yeast ◽  
Temperature Sensitive ◽  
Cytoplasmic Microtubule ◽  
Tetratricopeptide Repeats ◽  
Late Anaphase ◽  
Amino Acid Repeats ◽  
Cold Sensitive ◽  
Essential Function

A novel anaphase block phenotype was found in fission yeast temperature-sensitive cut9 mutants. Cells enter mitosis with chromosome condensation and short spindle formation, then block anaphase, but continue to progress into postanaphase events such as degradation of the spindle, reformation of the postanaphase cytoplasmic microtubule arrays, septation, and cytokinesis. The cut9 mutants are defective in the onset of anaphase and possibly in the restraint of postanaphase events until the completion of anaphase. The cut9+ gene encodes a 78-kD protein containing the 10 34-amino acid repeats, tetratricopeptide repeats (TPR), and similar to budding yeast Cdc16. It is essential for viability, and the mutation sites reside in the TPR. The three genes, namely, nuc2+, scn1+, and scn2+, genetically interact with cut9+. The nuc2+ and cut9+ genes share an essential function to initiate anaphase. The cold-sensitive scn1 and scn2 mutations, defective in late anaphase, can suppress the ts phenotype of cut9.

scholarly journals Sro7p, a Saccharomyces cerevisiae Counterpart of the Tumor Suppressor l(2)gl Protein, Is Related to Myosins in Function

Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 1717-1727 ◽  
Author(s):  
Mitsuhiro Kagami ◽  
Akio Toh-e ◽  
Yasushi Matsui
Keyword(s):  
Tumor Suppressor ◽  
Suppressor Gene ◽  
Small Gtpase ◽  
Genetic Interactions ◽  
Type Ii ◽  
Multicopy Suppressor ◽  
Human Counterpart ◽  
Cold Sensitive ◽  
Type V ◽  
Type Ii Myosin

Abstract Yeast SRO7 was identified as a multicopy suppressor of a defect in Rho3p, a small GTPase that maintains cell polarity. Sro7p and Sro77p, a homologue of Sro7p, possess domains homologous to the protein that are encoded by the Drosophila tumor suppressor gene lethal (2) giant larvae [l(2)gl]. sro7Δ sro77Δ mutants showed a partial defect of organization of the polarized actin cytoskeleton and a cold-sensitive growth phenotype. A human counterpart of l(2)gl could suppress the sro7Δ sro77Δ defect. Similar to the l(2)gl protein, Sro7p formed a complex with Myo1p, a type II myosin. These results indicate that Sro7p and Sro77p are the yeast counterparts of the l(2)gl protein. Our genetic analysis revealed that deletion of SRO7 and SRO77 showed reciprocal suppression with deletion of MYO1 (i.e., the sro7Δ sro77Δ defect was suppressed by myo1Δ and vice versa). In addition, SRO7 showed genetic interactions with MYO2, encoding an essential type V myosin: Overexpression of SRO7 suppressed a defect in MYO2 and, conversely, overexpression of MYO2 suppressed the cold-sensitive phenotype of sro7Δ sro77Δ mutants. These results indicate that Sro7 function is closely related to both Myo1p and Myo2p. We propose a model in which Sro7 function is involved in the targeting of the myosin proteins to their intrinsic pathways.

Stacking of Golgi cisternae in Schizosaccharomyces pombe requires intact microtubules

1993 ◽  
Vol 106 (4) ◽  
pp. 1227-1237 ◽  
Author(s):  
K. Ayscough ◽  
N.M. Hajibagheri ◽  
R. Watson ◽  
G. Warren
Keyword(s):  
Acid Phosphatase ◽  
Fission Yeast ◽  
Mutant Strain ◽  
Permissive Temperature ◽  
Half Time ◽  
Sensitive Mutant ◽  
Cold Sensitive ◽  
Cytoplasmic Microtubules ◽  
Microtubular Network

Fission yeast was treated with the anti-microtubule agent, thiabendazole. Cytoplasmic microtubules broke down with a half-time of less than 10 minutes followed closely by the unstacking of Golgi cisternae. The final product appeared to be single Golgi cisternae. No other organelle seemed to be affected by this treatment, which was completely reversible. The nda3 mutant strain has an altered beta-tubulin and its cytoplasmic microtubules are resistant to thiabendazole. The Golgi in this cold-sensitive mutant was unaffected by treatment at the permissive temperature but unstacked at the non-permissive temperature even in the absence of thiabendazole. Taken together these data show that disruption of the microtubular network can cause dissociation of Golgi cisternae. Newly synthesised acid phosphatase was transported and secreted to the same extent and with the same kinetics whether or not the Golgi was unstacked. The possible role of microtubules in Golgi stacking and the lack of effect on secretion are discussed.

scholarly journals A Pcl-like Cyclin Activates the Res2p-Cdc10p Cell Cycle “Start” Transcriptional Factor Complex in Fission Yeast

2000 ◽  
Vol 11 (9) ◽  
pp. 2845-2862 ◽  
Author(s):  
Koichi Tanaka ◽  
Hiroto Okayama
Keyword(s):  
Cell Cycle ◽  
Genetic Analysis ◽  
Fission Yeast ◽  
Budding Yeast ◽  
Mitotic Cell ◽  
Mating Pheromone ◽  
Yeast Saccharomyces Cerevisiae ◽  
Multicopy Suppressor ◽  
Pheromone Signaling

In the fission yeast Schizosaccharomyces pombe, the “start” of the cell cycle is controlled by the two functionally redundant transcriptional regulator complexes, Res1p-Cdc10p and Res2p-Cdc10p, that activate genes essential for the onset and progression of S phase. The activity of the Res2p-Cdc10p complex is regulated at least by the availability of the Rep2trans-activator subunit in the mitotic cell cycle. We have recently isolated the pas1+gene as a multicopy suppressor of the res1 null mutant. This gene encodes a novel cyclin that shares homology with the Pho85 kinase–associated cyclins of the budding yeast Saccharomyces cerevisiae. Genetic analysis reveals that Pas1 cyclin is unrelated to phosphate metabolism and stimulates the G1-S transition by specifically activating the Res2p-Cdc10p complex independently of Rep2p. Pas1 cyclin also controls mating pheromone signaling. Cells lacking pas1+are highly sensitive to mating pheromone, responding with facilitated G1arrest and premature commitment to conjugation. Pas1 cyclin associates in vivo with both Cdc2 and Pef1 kinases, the latter of which is a fission yeast counterpart of the budding yeast Pho85 kinase, but genetic analysis indicates that the Pef1p-associated Pas1p is responsible for the activation of Res2p-Cdc10p during the G1-S transition.

scholarly journals A New Member of the Sin3 Family of Corepressors Is Essential for Cell Viability and Required for Retroelement Propagation in Fission Yeast

1999 ◽  
Vol 19 (3) ◽  
pp. 2351-2365 ◽  
Author(s):  
Van Dinh Dang ◽  
Michael J. Benedik ◽  
Karl Ekwall ◽  
Jeannie Choi ◽  
Robin C. Allshire ◽  
...  
Keyword(s):  
Cell Viability ◽  
Fission Yeast ◽  
Histone Deacetylases ◽  
Immunofluorescence Microscopy ◽  
Trichostatin A ◽  
Critical Role ◽  
Predicted Amino Acid Sequence ◽  
Significant Similarity ◽  
Isolation And Characterization ◽  
Histone Deacetylase Inhibitor Trichostatin

ABSTRACT Tf1 is a long terminal repeat (LTR)-containing retrotransposon that propagates within the fission yeast Schizosaccharomyces pombe. LTR-retrotransposons possess significant similarity to retroviruses and therefore serve as retrovirus models. To determine what features of the host cell are important for the proliferation of this class of retroelements, we screened for mutations in host genes that reduced the transposition activity of Tf1. We report here the isolation and characterization of pst1 +, a gene required for Tf1 transposition. The predicted amino acid sequence of Pst1p possessed high sequence homology with the Sin3 family of proteins, known for their interaction with histone deacetylases. However, unlike the SIN3 gene of Saccharomyces cerevisiae, pst1 + is essential for cell viability. Immunofluorescence microscopy indicated that Pst1p was localized in the nucleus. Consistent with the critical role previously reported for Sin3 proteins in the histone acetylation process, we found that the growth of the strain with thepst1-1 allele was supersensitive to the specific histone deacetylase inhibitor trichostatin A. However, our analysis of strains with the pst1-1 mutation was unable to detect any changes in the acetylation of specific lysines of histones H3 and H4 as measured in bulk chromatin. Interestingly, the pst1-1mutant strain produced wild-type levels of Tf1-encoded proteins and cDNA, indicating that the defect in transposition occurred after reverse transcription. The results of immunofluorescence microscopy showed that the nuclear localization of the Tf1 capsid protein was disrupted in the strain with the pst1-1mutation, indicating an important role of pst1 +in modulating the nuclear import of Tf1 virus-like particles.

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