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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: 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.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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Examples of pheromone-regulated lacZ fusions. Seven  yeast strains containing the lacZ fusions indicated were incubated  in YPD medium in either the absence (left) or presence (right) of  pheromone for 12 h. Examples are shown of strains with fusions  in genes whose expression is dependent upon mating pheromone  (FUS2, FIG1, FIG2, and FIG4), enhanced by pheromone (CIK1,  KAR5/FIG3), or repressed by pheromone (FOX2).
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Figure 1: Examples of pheromone-regulated lacZ fusions. Seven yeast strains containing the lacZ fusions indicated were incubated in YPD medium in either the absence (left) or presence (right) of pheromone for 12 h. Examples are shown of strains with fusions in genes whose expression is dependent upon mating pheromone (FUS2, FIG1, FIG2, and FIG4), enhanced by pheromone (CIK1, KAR5/FIG3), or repressed by pheromone (FOX2).

Mentions: 55,000 transformants of a diploid strain and 36,200 transformants of a haploid strain were screened for β-gal expression in the presence and absence of α-factor. 186 strains were identified that reproducibly exhibited increased β-gal activity after pheromone treatment; three strains displayed decreased activity after treatment. Examples of the pheromone regulated–β-gal expression levels observed for lacZ fusions in the four novel FIG genes further characterized in this study, and an example of the class of pheromone-repressed genes are presented in Fig. 1.


Pheromone-regulated genes required for yeast mating differentiation.

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

Examples of pheromone-regulated lacZ fusions. Seven  yeast strains containing the lacZ fusions indicated were incubated  in YPD medium in either the absence (left) or presence (right) of  pheromone for 12 h. Examples are shown of strains with fusions  in genes whose expression is dependent upon mating pheromone  (FUS2, FIG1, FIG2, and FIG4), enhanced by pheromone (CIK1,  KAR5/FIG3), or repressed by pheromone (FOX2).
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Related In: Results  -  Collection

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

Figure 1: Examples of pheromone-regulated lacZ fusions. Seven yeast strains containing the lacZ fusions indicated were incubated in YPD medium in either the absence (left) or presence (right) of pheromone for 12 h. Examples are shown of strains with fusions in genes whose expression is dependent upon mating pheromone (FUS2, FIG1, FIG2, and FIG4), enhanced by pheromone (CIK1, KAR5/FIG3), or repressed by pheromone (FOX2).
Mentions: 55,000 transformants of a diploid strain and 36,200 transformants of a haploid strain were screened for β-gal expression in the presence and absence of α-factor. 186 strains were identified that reproducibly exhibited increased β-gal activity after pheromone treatment; three strains displayed decreased activity after treatment. Examples of the pheromone regulated–β-gal expression levels observed for lacZ fusions in the four novel FIG genes further characterized in this study, and an example of the class of pheromone-repressed genes are presented in Fig. 1.

Bottom Line: 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.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