Morphogenic effects of alpha-factor on Saccharomyces cerevisiae a cells

Abstract

Saccharomyces cerevisiae mating type a cells enlarged and elongated when exposed to a-factor, a sex pheromone produced by mating-type a cells. This morphogenesis required exogenous 1)-glucose, nitrogen, and phosphate, and cells in exponential phase responded better than stationary-phase cells. Morphogenesis was blocked by cycloheximide and by inhibitors of cell wall biosynthesis such as 2-deoxy-D>glucose, 2-deoxy-2-fluoro-D>glucose, and 2-deoxy-2-fluoro-D-mannose, but not by polyoxin D. One to two hours after addition of pheromone, a cells became more susceptible to lysis by glucanases, a change that was dependent on the dose of a-factor and was blocked by drugs that block morphogenesis. On the other hand, treatment with a-factor did not increase susceptibility to attack by trypsin, subtilisin, or exoa-mannanase. Radioactive label, incorporated into cell wall polysaccharides during treatment with a-factor, was not secreted into the medium during morphogenesis. Analysis of the labeled wall polymers showed that a-factor-treated cells contain more glucan and less mannan than control cells, and that the mannan of treated cells contains an increased proportion of shorter side chains and unsubstituted backbone mannose units. Thin-section electron microscopy oftreated cells revealed that the cell wall possesses a diffuse outer layer in the extension and is thinner at the tip.

Cellular morphogenesis in the Saccharomyces cerevisiae cell cycle: Localization of the CDC11 gene product and the timing of events at the budding site

“…Here we report the preparation of antibodies specific for the CDCll gene product (Cdcllp) and the use of these antibodies to localize this protein within cells in patterns very similar to those observed for CdcSp, CdclOp, and Cdcl2p. We have also examined the timing of arrival of both Cdcl l p and actin at presumptive budding sites, the timing of departure of these proteins from old budding sites after cytokinesis, and the localization of Cdcllp in cells undergoing morphogenetic changes during mating or in response to mating pheromone [Lipke et al, 1976;Schekman and Brawley, 1979;Tkacz and MacKay, 1979;HaSek et al, 1987;Trueheart et al, 19871.…”

Mating pheromones of the fission yeast Schizosaccharomyces pombe: purification and structural characterization of M-factor and isolation and analysis of two genes encoding the pheromone.

“…Conjugation between two haploid cells of heterothallic yeasts is generally controlled by the reciprocal action of pheromones, cells of each mating type releasing pheromones which induce mating specific changes in cells of the opposite mating type. These changes are best characterized in the budding yeast Saccharomyces cerevisiae (reviewed in Cross et al, 1988) and include altered patterns of gene transcription (Stetler and Thorner, 1984), an increase in cell agglutinability (Fehrenbacher et al, 1978), a GI arrest of cell growth (Hartwell, 1973) and a unidirectional elongation of the cell to form a shmoo (Lipke et al, 1976). The two cell types subsequently conjugate to form a diploid zygote which can undergo meiotic division and sporulation to release ascospores to germinate to haploid cells and complete the life cycle.…”

Isolation and quantitation of M‐factor, a diffusible mating factor from the fission yeast Schizosaccharomyces pombe

“…These changes include alterations in the transcriptional pattern (Stetler and Thorner, 1984), an increase in cell agglutinability (Fehrenbacher et al, 1978) and an inhibition of cell division at the G1 stage of the cell cycle (Hartwell, 1973). There is also a change in cell morphology as a specific elongation of the cell leads to the formation of a shmoo (Lipke et al, 1976). The two cell types subsequently conjugate to form a diploid zygote which can undergo either mitotic division to form diploid cells or meiotic division and sporulation to release ascospores which germinate to haploid cells to complete the life cycle.…”