The a-factor pheromone of Saccharomyces cerevisiae is essential for mating

1988 ◽  
Vol 8 (3) ◽  
pp. 1309-1318 ◽  
Author(s):  
S Michaelis ◽  
I Herskowitz
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Double Mutant ◽  
Protein Transport ◽  
Factor Activity ◽  
Structural Genes ◽  
Wild Type ◽  
Mating Partner ◽  
Cycle Arrest ◽  
A Cells ◽  
A Cell

The Saccharomyces cerevisiae pheromone a-factor is produced by a cells and interacts with alpha cells to cause cell cycle arrest and other physiological responses associated with mating. Two a-factor structural genes, MFA1 and MFA2, have been previously cloned with synthetic probes based on the a-factor amino acid sequence (A. Brake, C. Brenner, R. Najarian, P. Laybourn, and J. Merryweather, cited in M.-J. Gething [ed.], Protein transport and secretion, 1985). We have examined the function of these genes in a-factor production and mating by construction and analysis of chromosomal null mutations. mfa1 and mfa2 single mutants each exhibited approximately half the wild-type level of a-factor activity and were proficient in mating, whereas the mfa1 mfa2 double mutant produced no a-factor and was unable to mate. These results demonstrate that both genes are functional, that each gene makes an equivalent contribution to the a-factor activity and mating capacity of a cells, and that a-factor plays an essential role in mating. Strikingly, exogenous a-factor did not alleviate the mating defect of the double mutant, suggesting that an a cell must be producing a-factor to be an effective mating partner.

scholarly journals The a-factor pheromone of Saccharomyces cerevisiae is essential for mating.

1988 ◽  
Vol 8 (3) ◽  
pp. 1309-1318 ◽  
Author(s):  
S Michaelis ◽  
I Herskowitz
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Double Mutant ◽  
Protein Transport ◽  
Factor Activity ◽  
Structural Genes ◽  
Wild Type ◽  
Mating Partner ◽  
Cycle Arrest ◽  
A Cells ◽  
A Cell

The Saccharomyces cerevisiae pheromone a-factor is produced by a cells and interacts with alpha cells to cause cell cycle arrest and other physiological responses associated with mating. Two a-factor structural genes, MFA1 and MFA2, have been previously cloned with synthetic probes based on the a-factor amino acid sequence (A. Brake, C. Brenner, R. Najarian, P. Laybourn, and J. Merryweather, cited in M.-J. Gething [ed.], Protein transport and secretion, 1985). We have examined the function of these genes in a-factor production and mating by construction and analysis of chromosomal null mutations. mfa1 and mfa2 single mutants each exhibited approximately half the wild-type level of a-factor activity and were proficient in mating, whereas the mfa1 mfa2 double mutant produced no a-factor and was unable to mate. These results demonstrate that both genes are functional, that each gene makes an equivalent contribution to the a-factor activity and mating capacity of a cells, and that a-factor plays an essential role in mating. Strikingly, exogenous a-factor did not alleviate the mating defect of the double mutant, suggesting that an a cell must be producing a-factor to be an effective mating partner.

scholarly journals Pheromones and pheromone receptors are the primary determinants of mating specificity in the yeast Saccharomyces cerevisiae.

Genetics ◽  
1989 ◽  
Vol 121 (3) ◽  
pp. 463-476 ◽  
Author(s):  
A Bender ◽  
G F Sprague
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Types ◽  
Haploid Cell ◽  
Wild Type ◽  
Cell Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
A Cells ◽  
Alpha Factor ◽  
A Cell ◽  
Specific Proteins

Abstract Saccharomyces cerevisiae has two haploid cell types, a and alpha, each of which produces a unique set of proteins that participate in the mating process. We sought to determine the minimum set of proteins that must be expressed to allow mating and to confer specificity. We show that the capacity to synthesize alpha-factor pheromone and a-factor receptor is sufficient to allow mating by mat alpha 1 mutants, mutants that normally do not express any alpha- or a-specific products. Likewise, the capacity to synthesize a-factor receptor and alpha-factor pheromone is sufficient to allow a ste2 ste6 mutants, which do not produce the normal a cell pheromone and receptor, to mate with wild-type a cells. Thus, the a-factor receptor and alpha-factor pheromone constitute the minimum set of alpha-specific proteins that must be produced to allow mating as an alpha cell. Further evidence that the pheromones and pheromone receptors are important determinants of mating specificity comes from studies with mat alpha 2 mutants, cells that simultaneously express both pheromones and both receptors. We created a series of strains that express different combinations of pheromones and receptors in a mat alpha 2 background. These constructions reveal that mat alpha 2 mutants can be made to mate as either a cells or as alpha cells by causing them to express only the pheromone and receptor set appropriate for a particular cell type. Moreover, these studies show that the inability of mat alpha 2 mutants to respond to either pheromone is a consequence of two phenomena: adaptation to an autocrine response to the pheromones they secrete and interference with response to alpha factor by the a-factor receptor.

scholarly journals Suppressors of a gpa1 mutation cause sterility in Saccharomyces cerevisiae.

Genetics ◽  
1988 ◽  
Vol 119 (4) ◽  
pp. 797-804
Author(s):  
I Miyajima ◽  
N Nakayama ◽  
M Nakafuku ◽  
Y Kaziro ◽  
K Arai ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fusion Gene ◽  
Lacz Fusion ◽  
Wild Type ◽  
Cell Type ◽  
Recessive Mutations ◽  
Cycle Arrest ◽  
Alpha Factor ◽  
A Cell ◽  
Mating Factor

Abstract The Saccharomyces cerevisiae GPA1 gene encodes a protein highly homologous to the alpha subunit of mammalian G proteins and is essential for haploid cell growth. We have selected 77 mutants able to suppress the lethality resulting from disruption of GPA1 (gpa1::HIS3). Two strains bearing either of two recessive mutations, sgp1 and sgp2, in combination with the disruption mutation, showed a cell type nonspecific sterile phenotype, yet expressed the major alpha-factor gene (MF alpha 1) as judged by the ability to express a MF alpha 1-lacZ fusion gene. The sgp1 mutation was closely linked to gpa1::HIS3 and probably occurred at the GPA1 locus. The sgp2 mutation was not linked to GPA1 and was different from the previously identified cell type nonspecific sterile mutations (ste4, ste5, ste7, ste11 and ste12). sgp2 GPA1 cells showed a fertile phenotype, indicating that the mating defect caused by sgp2 is associated with the loss of GPA1 function. While expression of a FUS1-lacZ fusion gene was induced in wild-type cells by the addition of alpha-factor, mutants bearing sgp1 or sgp2 as well as gpa1::HIS3 constitutively expressed FUS1-lacZ. These observations suggest that GPA1 (SGP1) and SGP2 are involved in mating factor-mediated signal transduction, which causes both cell cycle arrest in the late G1 phase and induction of genes necessary for mating such as FUS1.

Significance of C-terminal cysteine modifications to the biological activity of the Saccharomyces cerevisiae a-factor mating pheromone

1991 ◽  
Vol 11 (7) ◽  
pp. 3603-3612
Author(s):  
S Marcus ◽  
G A Caldwell ◽  
D Miller ◽  
C B Xue ◽  
F Naider ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Biological Activity ◽  
Methyl Ester ◽  
Total Synthesis ◽  
Biologically Active ◽  
Structural Genes ◽  
Wild Type ◽  
Mating Pheromone ◽  
Carboxy Terminal

We have undertaken total synthesis of the Saccharomyces cerevisiae a-factor (NH2-YIIKGVFWDPAC[S-farnesyl]-COOCH3) and several Cys-12 analogs to determine the significance of S-farnesylation and carboxy-terminal methyl esterification to the biological activity of this lipopeptide mating pheromone. Replacement of either the farnesyl group or the carboxy-terminal methyl ester by a hydrogen atom resulted in marked reduction but not total loss of bioactivity as measured by a variety of assays. Moreover, both the farnesyl and methyl ester groups could be replaced by other substituents to produce biologically active analogs. The bioactivity of a-factor decreased as the number of prenyl units on the cysteine sulfur decreased from three to one, and an a-factor analog having the S-farnesyl group replaced by an S-hexadecanyl group was more active than an S-methyl a-factor analog. Thus, with two types of modifications, a-factor activity increased as the S-alkyl group became bulkier and more hydrophobic. MATa cells having deletions of the a-factor structural genes (mfal1 mfa2 mutants) were capable of mating with either sst2 or wild-type MAT alpha cells in the presence of exogenous a-factor, indicating that it is not absolutely essential for MATa cells to actively produce a-factor in order to mate. Various a-factor analogs were found to partially restore mating to these strains as well, and their relative activities in the mating restoration assay were similar to their activities in the other assays used in this study. Mating was not restored by addition of exogenous a-factor to a cross of a wild-type MAT alpha strain and a MATaste6 mutant, indicating a role of the STE6 gene product in mating in addition to its secretion of a-factor.

Quantitation of alpha-factor internalization and response during the Saccharomyces cerevisiae cell cycle

1991 ◽  
Vol 11 (10) ◽  
pp. 5251-5258
Author(s):  
B Zanolari ◽  
H Riezman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Surface ◽  
Cell Surface Receptors ◽  
Specific Cell ◽  
Surface Receptors ◽  
Cycle Arrest ◽  
A Cells ◽  
Alpha Factor ◽  
Inducible Genes

The alpha-factor pheromone binds to specific cell surface receptors on Saccharomyces cerevisiae a cells. The pheromone is then internalized, and cell surface receptors are down-regulated. At the same time, a signal is transmitted that causes changes in gene expression and cell cycle arrest. We show that the ability of cells to internalize alpha-factor is constant throughout the cell cycle, a cells are also able to respond to pheromone throughout the cycle even though there is cell cycle modulation of the expression of two pheromone-inducible genes, FUS1 and STE2. Both of these genes are expressed less efficiently near or just after the START point of the cell cycle in response to alpha-factor. For STE2, the basal level of expression is modulated in the same manner.

scholarly journals Significance of C-terminal cysteine modifications to the biological activity of the Saccharomyces cerevisiae a-factor mating pheromone.

1991 ◽  
Vol 11 (7) ◽  
pp. 3603-3612 ◽  
Author(s):  
S Marcus ◽  
G A Caldwell ◽  
D Miller ◽  
C B Xue ◽  
F Naider ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Biological Activity ◽  
Methyl Ester ◽  
Total Synthesis ◽  
Biologically Active ◽  
Structural Genes ◽  
Wild Type ◽  
Mating Pheromone ◽  
Carboxy Terminal

We have undertaken total synthesis of the Saccharomyces cerevisiae a-factor (NH2-YIIKGVFWDPAC[S-farnesyl]-COOCH3) and several Cys-12 analogs to determine the significance of S-farnesylation and carboxy-terminal methyl esterification to the biological activity of this lipopeptide mating pheromone. Replacement of either the farnesyl group or the carboxy-terminal methyl ester by a hydrogen atom resulted in marked reduction but not total loss of bioactivity as measured by a variety of assays. Moreover, both the farnesyl and methyl ester groups could be replaced by other substituents to produce biologically active analogs. The bioactivity of a-factor decreased as the number of prenyl units on the cysteine sulfur decreased from three to one, and an a-factor analog having the S-farnesyl group replaced by an S-hexadecanyl group was more active than an S-methyl a-factor analog. Thus, with two types of modifications, a-factor activity increased as the S-alkyl group became bulkier and more hydrophobic. MATa cells having deletions of the a-factor structural genes (mfal1 mfa2 mutants) were capable of mating with either sst2 or wild-type MAT alpha cells in the presence of exogenous a-factor, indicating that it is not absolutely essential for MATa cells to actively produce a-factor in order to mate. Various a-factor analogs were found to partially restore mating to these strains as well, and their relative activities in the mating restoration assay were similar to their activities in the other assays used in this study. Mating was not restored by addition of exogenous a-factor to a cross of a wild-type MAT alpha strain and a MATaste6 mutant, indicating a role of the STE6 gene product in mating in addition to its secretion of a-factor.

Exploratory analysis of the effect of taselisib on downstream pathway modulation and correlation with tumor response in ER-positive/HER2-negative early-stage breast cancer from the LORELEI trial.

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. 1050-1050 ◽  
Author(s):  
Paolo Nuciforo ◽  
Dominik Hlauschek ◽  
Cristina Saura ◽  
Evandro de Azambuja ◽  
Roberta Fasani ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Early Stage ◽  
Objective Response ◽  
Wild Type ◽  
Cycle Arrest ◽  
Er Positive ◽  
A Cell ◽  
Tumor Biopsies ◽  
Clinical Trial Information

1050 Background: Taselisib (T) is an oral, potent, selective inhibitor of Class I PI3-kinase with enhanced activity against PIK3CA mutant cancer cells. Results from the LORELEI trial have demonstrated a significant improvement in ORR (objective response rate) by centrally assessed magnetic resonance imaging in all randomized patients as well as in the PIK3CA mutant (MT) cohort treated with neoadjuvant T plus letrozole (L) compared to placebo (P) plus L. Here we present the results of exploratory analyses of selected pathway-related phosphoproteins. Methods: Baseline (BL) and week3 (W3) tumor biopsies were obtained from 334 patients enrolled in the trial. Phosphoproteins (pAKT, pPRAS40 and pS6) were analyzed by IHC. BL levels as well as changes from BL to W3 were correlated with response assessed either by ORR or cell cycle arrest (Ki67 at W3 < 2.7%). Results: In the overall population, BL phosphoproteins levels were similar between the T and P arms. Higher pAKT (p < 0.001) and pPRAS40 (p = 0.004) levels were observed in MT vs wild-type (WT), whereas the opposite result was found for pS6 (p = 0.03). Treatment-induced absolute changes of phosphoproteins adjusted for BL levels were not significantly different between the T and P arms in the overall population, except for pPRAS40 with higher decrease in the T arm (p = 0.014). After stratification for PIK3CA genotype, a significantly greater decrease in expression levels was observed for pPRAS40 (p < 0.001) and pS6 (p = 0.020) in MT tumors treated with T. The treatment effects were not significantly different in the WT population. A trend for an association between decrease in pS6 levels at W3 and improved ORR was observed in the MT (p = 0.08) and T (p = 0.09) subgroups. The magnitude of pS6 suppression at W3 was higher in tumors achieving a cell cycle arrest in the MT/T subgroup (biserial correlation = -0.473). Conclusions: Exploratory analyses of phosphoproteins showed bioactivity of taselisib as indicated by downstream pathway suppression. Translational research aiming to integrate these results with additional exploratory biomarkers data is currently ongoing. Clinical trial information: NCT02273973.

Cell surface specific immunoglobulin inhibits α factor mediated morphogenesis in Saccharomyces cerevisiae

1987 ◽  
Vol 33 (4) ◽  
pp. 331-335
Author(s):  
Glenn J. Merkel ◽  
Charles L. Phelps ◽  
Roger W. Roeske
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Surface ◽  
Mating Type ◽  
Cell Envelope ◽  
Whole Cells ◽  
Cycle Arrest ◽  
Immunoglobulin Preparations ◽  
Specific Immunoglobulin ◽  
A Cell ◽  
Immunoglobulin Binding

Immunoglobulins raised from Saccharomyces cerevisiae a and α mating type cell envelope preparations inhibited α factor mediated morphogenesis of the a cell without inhibiting normal cell division. The Ig responsible for this inhibition was absorbed to both a and α whole cells and heat-killed cells, indicating that the immunoglobulin binding sites were exposed on the cell surface and not mating type specific. Additionally, α factor mediated cell cycle arrest was not affected by the immunoglobulin preparations, implying that the immunoglobulin was not preventing α factor from binding to its receptor.

scholarly journals A cell sizer network involving Cln3 and Far1 controls entrance into S phase in the mitotic cycle of budding yeast

2004 ◽  
Vol 167 (3) ◽  
pp. 433-443 ◽  
Author(s):  
Lilia Alberghina ◽  
Riccardo L. Rossi ◽  
Lorenzo Querin ◽  
Valeria Wanke ◽  
Marco Vanoni
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Replication ◽  
Carbon Source ◽  
Protein Content ◽  
Cell Size ◽  
Mitotic Cycle ◽  
S Phase ◽  
Wild Type ◽  
Bud Emergence ◽  
A Cell

Saccharomyces cerevisiae must reach a carbon source-modulated critical cell size, protein content per cell at the onset of DNA replication (Ps), in order to enter S phase. Cells grown in glucose are larger than cells grown in ethanol. Here, we show that an increased level of the cyclin-dependent inhibitor Far1 increases cell size, whereas far1Δ cells start bud emergence and DNA replication at a smaller size than wild type. Cln3Δ, far1Δ, and strains overexpressing Far1 do not delay budding during an ethanol glucose shift-up as wild type does. Together, these findings indicate that Cln3 has to overcome Far1 to trigger Cln–Cdc28 activation, which then turns on SBF- and MBF-dependent transcription. We show that a second threshold is required together with the Cln3/Far1 threshold for carbon source modulation of Ps. A new molecular network accounting for the setting of Ps is proposed.

scholarly journals Quantitation of alpha-factor internalization and response during the Saccharomyces cerevisiae cell cycle.

1991 ◽  
Vol 11 (10) ◽  
pp. 5251-5258 ◽  
Author(s):  
B Zanolari ◽  
H Riezman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Surface ◽  
Cell Surface Receptors ◽  
Specific Cell ◽  
Surface Receptors ◽  
Cycle Arrest ◽  
A Cells ◽  
Alpha Factor ◽  
Inducible Genes

The alpha-factor pheromone binds to specific cell surface receptors on Saccharomyces cerevisiae a cells. The pheromone is then internalized, and cell surface receptors are down-regulated. At the same time, a signal is transmitted that causes changes in gene expression and cell cycle arrest. We show that the ability of cells to internalize alpha-factor is constant throughout the cell cycle, a cells are also able to respond to pheromone throughout the cycle even though there is cell cycle modulation of the expression of two pheromone-inducible genes, FUS1 and STE2. Both of these genes are expressed less efficiently near or just after the START point of the cell cycle in response to alpha-factor. For STE2, the basal level of expression is modulated in the same manner.

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