Analysis of the structural genes encoding M-factor in the fission yeast Schizosaccharomyces pombe: identification of a third gene, mfm3

1994 ◽  
Vol 14 (6) ◽  
pp. 3895-3905
Author(s):  
S Kjaerulff ◽  
J Davey ◽  
O Nielsen
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Mutational Analysis ◽  
M Cells ◽  
Gene Products ◽  
Structural Genes ◽  
Triple Mutant ◽  
Isolation And Characterization ◽  
Genes Encoding

We previously identified two genes, mfm1 and mfm2, with the potential to encode the M-factor mating pheromone of the fission yeast Schizosaccharomyces pombe (J. Davey, EMBO J. 11:951-960, 1992), but further analysis revealed that a mutant strain lacking both genes still produced active M-factor. Here we describe the isolation and characterization of a third M-factor gene, mfm3. A mutant lacking all three genes fails to produce M-factor, indicating that all functional M-factor genes now have been identified. The triple mutant exhibits an absolute mating defect in M cells, a defect that is not rescued by addition of exogenous M-factor. A mutational analysis reveals that all three mfm genes contribute to the production of M-factor. Their transcription is limited to M cells and requires the mat1-Mc and ste11 gene products. Each gene is induced when the cells are starved of nitrogen and further induced by a pheromone signal. Additionally, the signal transduction machinery associated with the pheromone response is required for transcription of the mfm genes in both stimulated and unstimulated cells.

scholarly journals Analysis of the structural genes encoding M-factor in the fission yeast Schizosaccharomyces pombe: identification of a third gene, mfm3.

1994 ◽  
Vol 14 (6) ◽  
pp. 3895-3905 ◽  
Author(s):  
S Kjaerulff ◽  
J Davey ◽  
O Nielsen
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Mutational Analysis ◽  
M Cells ◽  
Gene Products ◽  
Structural Genes ◽  
Triple Mutant ◽  
Isolation And Characterization ◽  
Genes Encoding

We previously identified two genes, mfm1 and mfm2, with the potential to encode the M-factor mating pheromone of the fission yeast Schizosaccharomyces pombe (J. Davey, EMBO J. 11:951-960, 1992), but further analysis revealed that a mutant strain lacking both genes still produced active M-factor. Here we describe the isolation and characterization of a third M-factor gene, mfm3. A mutant lacking all three genes fails to produce M-factor, indicating that all functional M-factor genes now have been identified. The triple mutant exhibits an absolute mating defect in M cells, a defect that is not rescued by addition of exogenous M-factor. A mutational analysis reveals that all three mfm genes contribute to the production of M-factor. Their transcription is limited to M cells and requires the mat1-Mc and ste11 gene products. Each gene is induced when the cells are starved of nitrogen and further induced by a pheromone signal. Additionally, the signal transduction machinery associated with the pheromone response is required for transcription of the mfm genes in both stimulated and unstimulated cells.

scholarly journals imp2, a New Component of the Actin Ring in the Fission Yeast Schizosaccharomyces pombe

1998 ◽  
Vol 143 (2) ◽  
pp. 415-427 ◽  
Author(s):  
Janos Demeter ◽  
Shelley Sazer
Keyword(s):  
Cell Division ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Model Organism ◽  
Eukaryotic Cell ◽  
Actin Ring ◽  
Daughter Cells ◽  
Isolation And Characterization ◽  
Ring Structures

Cytokinesis is the part of the cell cycle in which the cell is cleaved to form two daughter cells. The unicellular yeast, Schizosaccharomyces pombe is an excellent model organism in which to study cell division, since it shows the general features of eukaryotic cell division and is amenable to genetic analysis. In this manuscript we describe the isolation and characterization of a new protein, imp2, which is required for normal septation in fission yeast. imp2, which colocalizes with the medial ring during septation, is structurally similar to a group of proteins including the S. pombe cdc15 and the mouse PSTPIP that are localized to, and thought to be involved in actin ring organization. Cells in which the imp2 gene is deleted or overexpressed have septation and cell separation defects. An analysis of the actin cytoskeleton shows the lack of a medial ring in septating cells that overexpress imp2, and the appearance of abnormal medial ring structures in septated cells that lack imp2. These observations suggest that imp2 destabilizes the medial ring during septation. imp2 also shows genetic interactions with several, previously characterized septation genes, strengthening the conclusion that it plays a role in normal fission yeast septation.

scholarly journals Isolation and characterization of a processive DNA helicase from the fission yeast Schizosaccharomyces pombe that translocates in a 5′-to-3′ direction

1998 ◽  
Vol 334 (2) ◽  
pp. 377-386 ◽  
Author(s):  
Changwoo LEE ◽  
Yeon-Soo SEO
Keyword(s):  
Atpase Activity ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Atp Hydrolysis ◽  
Sedimentation Coefficient ◽  
Dna Helicase ◽  
Single Stranded Dna ◽  
Dna Helicase Ii ◽  
Isolation And Characterization

We report here the isolation and characterization of a novel DNA helicase from extracts of the fission yeast Schizosaccharomyces pombe. The enzyme, called DNA helicase II, also contains an intrinsic DNA-dependent ATPase activity. Both the helicase and ATPase activities co-purified with a 63 kDa polypeptide on an SDS/polyacrylamide gel. The protein has a sedimentation coefficient of 4.8 S and a Stokes radius of 36 Å (3.6 nm); from these data the native molecular mass was calculated to be 65 kDa. The enzyme translocates in a 5´-to-3´ direction with respect to the substrate strand to which it is bound. Unwinding reactions carried out in the presence of increasing enzyme showed a sigmoidal curve, suggesting either co-operative interactions between monomers or multimerization of DNA helicase II in the presence of single-stranded DNA and/or ATP. This enzyme favoured adenosine nucleotides (ATP and dATP) as its energy source, but utilized to limited extents GTP, CTP, dGTP and dCTP. Non-hydrolysable ATP analogues did not support helicase activity. Kinetic analyses showed that the unwinding reaction was rapid, being complete after 50–100 s of incubation. Addition of unlabelled substrates to the helicase reaction after preincubation of the enzyme with substrate did not significantly diminish unwinding. The ATPase activity of DNA helicase II increased proportionally with increasing lengths of single-stranded DNA cofactor. In the presence of circular DNA, ATP hydrolysis continued to increase up to the longest time tested (3 h), whereas it ceased to increase after 5–10 min in the presence of shorter oligonucleotides. The initial rate of ATP hydrolysis during the first 5 min of incubation time was not affected by DNA species used. These data indicate that the enzyme does not dissociate from the single-stranded DNA once it is bound and is therefore highly processive.

scholarly journals Isolation and Characterization of par1+ and par2+: Two Schizosaccharomyces pombe Genes Encoding B′ Subunits of Protein Phosphatase 2A

Genetics ◽  
2000 ◽  
Vol 154 (3) ◽  
pp. 1025-1038 ◽  
Author(s):  
Wei Jiang ◽  
Richard L Hallberg
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Amino Acid Sequence Level ◽  
Isolation And Characterization ◽  
Genes Encoding ◽  
Phosphatase 2A ◽  
A Cell ◽  
B Subunits

Abstract Protein phosphatase 2A (PP2A) is one of the major serine/threonine phosphatases found in eukaryotic cells. We cloned two genes, par1+ and par2+, encoding distinct B′ subunits of PP2A in fission yeast. They share 52% identity at the amino acid sequence level. Neither gene is essential but together they are required for normal septum positioning and cytokinesis, for growth at both high and low temperature, and for growth under a number of stressful conditions. Immunofluorescence microscopy revealed that Par2p has a cell-cycle-related localization pattern, being localized at cell ends during interphase and forming a medial ring in cells that are undergoing septation and cytokinesis. Our analyses also indicate that Par1p is more abundant than Par2p in the cell. Cross-organism studies showed that both par1+ and par2+ could complement the rts1Δ allele in Saccharomyces cerevisiae, albeit to different extents, in spite of the fact that neither contains a serine/threonine-rich N-terminal domain like that found in the S. cerevisiae homolog Rts1p. Thus, while Schizosaccharomyces pombe is more similar to higher eukaryotes with respect to its complement of B′-encoding genes, the function of those proteins is conserved relative to that of Rts1p.

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