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Pheromone-regulated genes required for yeast mating differentiation.

Erdman S, Lin L, Malczynski M, Snyder M - J. Cell Biol. (1998)

Bottom Line: Mutations in four novel genes, FIG1, FIG2, KAR5/ FIG3, and FIG4 were found to cause mating defects.Fig4p is a member of a family of eukaryotic proteins that contain a domain homologous to the yeast Sac1p.Our results indicate that a variety of novel genes are expressed specifically during mating differentiation to mediate proper cell morphogenesis, cell fusion, and other steps of the mating process.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Yale University, New Haven, Connecticut 06520-8103, USA.

ABSTRACT
Yeast cells mate by an inducible pathway that involves agglutination, mating projection formation, cell fusion, and nuclear fusion. To obtain insight into the mating differentiation of Saccharomyces cerevisiae, we carried out a large-scale transposon tagging screen to identify genes whose expression is regulated by mating pheromone. 91,200 transformants containing random lacZ insertions were screened for beta-galactosidase (beta-gal) expression in the presence and absence of alpha factor, and 189 strains containing pheromone-regulated lacZ insertions were identified. Transposon insertion alleles corresponding to 20 genes that are novel or had not previously been known to be pheromone regulated were examined for effects on the mating process. Mutations in four novel genes, FIG1, FIG2, KAR5/ FIG3, and FIG4 were found to cause mating defects. Three of the proteins encoded by these genes, Fig1p, Fig2p, and Fig4p, are dispensible for cell polarization in uniform concentrations of mating pheromone, but are required for normal cell polarization in mating mixtures, conditions that involve cell-cell communication. Fig1p and Fig2p are also important for cell fusion and conjugation bridge shape, respectively. The fourth protein, Kar5p/Fig3p, is required for nuclear fusion. Fig1p and Fig2p are likely to act at the cell surface as Fig1:: beta-gal and Fig2::beta-gal fusion proteins localize to the periphery of mating cells. Fig4p is a member of a family of eukaryotic proteins that contain a domain homologous to the yeast Sac1p. Our results indicate that a variety of novel genes are expressed specifically during mating differentiation to mediate proper cell morphogenesis, cell fusion, and other steps of the mating process.

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Phenotypes of double figΔ mutants affecting  mating projection and zygote  morphology. A typical polarized cell (Mating Projection)  and zygote from bilateral matings of fig1Δ fig2Δ cells (top),  fig1Δ fig4Δ cells (middle) and  fig2Δ fig4Δ cells (bottom) is  shown.
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Figure 9: Phenotypes of double figΔ mutants affecting mating projection and zygote morphology. A typical polarized cell (Mating Projection) and zygote from bilateral matings of fig1Δ fig2Δ cells (top), fig1Δ fig4Δ cells (middle) and fig2Δ fig4Δ cells (bottom) is shown.

Mentions: The different effects of nonoptimal mating conditions on the mating efficiencies of fig1Δ, fig2Δ, and fig4Δ strains suggested that these mutants are defective in different pathways involved in mating cell differentiation (Table IV). To investigate this further, we examined the epistatic relationships of the figΔ mutations by characterizing the mating cell projection and zygote morphologies of double mutant strains mated at 30° and 16°C; bilateral matings of MATa and MATα fig1Δfig2Δ, fig1Δfig4Δ, and fig2Δfig4Δ mutant strains were examined (Fig. 9). For most of the double mutant strains, the phenotype of any single mutation was never completely epistatic to that of another (Table VII). All double mutants carrying the fig1Δ mutation displayed reductions in the fraction of cells producing pointed mating projections and increases in the rate of cell fusion defects. Similarly, double mutants involving the fig2Δ mutation displayed a narrow conjugation bridge and the aberrant nuclear morphology phenotypes; these mutants also hyperagglutinated at both 30° and 16°C. All double mutants involving the fig4Δ mutation displayed a reduction in the percentage of cells with pointed projections. Thus, the morphological phenotypes of the fig1Δfig2Δ and fig2Δfig4Δ double mutants represent a combination of those observed in each of the corresponding single mutants, suggesting that Fig2p functions in a distinct pathway from that of either Fig1p or Fig4p (Table VII).


Pheromone-regulated genes required for yeast mating differentiation.

Erdman S, Lin L, Malczynski M, Snyder M - J. Cell Biol. (1998)

Phenotypes of double figΔ mutants affecting  mating projection and zygote  morphology. A typical polarized cell (Mating Projection)  and zygote from bilateral matings of fig1Δ fig2Δ cells (top),  fig1Δ fig4Δ cells (middle) and  fig2Δ fig4Δ cells (bottom) is  shown.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2140177&req=5

Figure 9: Phenotypes of double figΔ mutants affecting mating projection and zygote morphology. A typical polarized cell (Mating Projection) and zygote from bilateral matings of fig1Δ fig2Δ cells (top), fig1Δ fig4Δ cells (middle) and fig2Δ fig4Δ cells (bottom) is shown.
Mentions: The different effects of nonoptimal mating conditions on the mating efficiencies of fig1Δ, fig2Δ, and fig4Δ strains suggested that these mutants are defective in different pathways involved in mating cell differentiation (Table IV). To investigate this further, we examined the epistatic relationships of the figΔ mutations by characterizing the mating cell projection and zygote morphologies of double mutant strains mated at 30° and 16°C; bilateral matings of MATa and MATα fig1Δfig2Δ, fig1Δfig4Δ, and fig2Δfig4Δ mutant strains were examined (Fig. 9). For most of the double mutant strains, the phenotype of any single mutation was never completely epistatic to that of another (Table VII). All double mutants carrying the fig1Δ mutation displayed reductions in the fraction of cells producing pointed mating projections and increases in the rate of cell fusion defects. Similarly, double mutants involving the fig2Δ mutation displayed a narrow conjugation bridge and the aberrant nuclear morphology phenotypes; these mutants also hyperagglutinated at both 30° and 16°C. All double mutants involving the fig4Δ mutation displayed a reduction in the percentage of cells with pointed projections. Thus, the morphological phenotypes of the fig1Δfig2Δ and fig2Δfig4Δ double mutants represent a combination of those observed in each of the corresponding single mutants, suggesting that Fig2p functions in a distinct pathway from that of either Fig1p or Fig4p (Table VII).

Bottom Line: Mutations in four novel genes, FIG1, FIG2, KAR5/ FIG3, and FIG4 were found to cause mating defects.Fig4p is a member of a family of eukaryotic proteins that contain a domain homologous to the yeast Sac1p.Our results indicate that a variety of novel genes are expressed specifically during mating differentiation to mediate proper cell morphogenesis, cell fusion, and other steps of the mating process.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Yale University, New Haven, Connecticut 06520-8103, USA.

ABSTRACT
Yeast cells mate by an inducible pathway that involves agglutination, mating projection formation, cell fusion, and nuclear fusion. To obtain insight into the mating differentiation of Saccharomyces cerevisiae, we carried out a large-scale transposon tagging screen to identify genes whose expression is regulated by mating pheromone. 91,200 transformants containing random lacZ insertions were screened for beta-galactosidase (beta-gal) expression in the presence and absence of alpha factor, and 189 strains containing pheromone-regulated lacZ insertions were identified. Transposon insertion alleles corresponding to 20 genes that are novel or had not previously been known to be pheromone regulated were examined for effects on the mating process. Mutations in four novel genes, FIG1, FIG2, KAR5/ FIG3, and FIG4 were found to cause mating defects. Three of the proteins encoded by these genes, Fig1p, Fig2p, and Fig4p, are dispensible for cell polarization in uniform concentrations of mating pheromone, but are required for normal cell polarization in mating mixtures, conditions that involve cell-cell communication. Fig1p and Fig2p are also important for cell fusion and conjugation bridge shape, respectively. The fourth protein, Kar5p/Fig3p, is required for nuclear fusion. Fig1p and Fig2p are likely to act at the cell surface as Fig1:: beta-gal and Fig2::beta-gal fusion proteins localize to the periphery of mating cells. Fig4p is a member of a family of eukaryotic proteins that contain a domain homologous to the yeast Sac1p. Our results indicate that a variety of novel genes are expressed specifically during mating differentiation to mediate proper cell morphogenesis, cell fusion, and other steps of the mating process.

Show MeSH
Related in: MedlinePlus