Saccharomyces cerevisiae mutants lacking a functional vacuole are defective for aspects of the pheromone response

1990 ◽  
Vol 97 (3) ◽  
pp. 517-525 ◽  
Author(s):  
V. Dulic ◽  
H. Riezman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Carbon Sources ◽  
Early Response ◽  
Pheromone Response ◽  
Optimal Response ◽  
Cycle Arrest ◽  
Alpha Factor ◽  
Vacuolar Protein

The end1 mutant belongs to a group of four vacuolar protein sorting mutants (class C vps) that lack a morphologically distinguishable and functional vacuole. These mutants share several other phenotypes, such as the inability to grow at 37 degrees C or on nonfermentable carbon sources. We show that, as in the case of the end1 mutant, vps16, vps18 and vps33 mutants all internalize but do not degrade alpha-factor. In addition, all four mutants are defective for alpha-factor-induced projection formation to the same extent. A more detailed investigation of pheromone response in the end1 mutant reveals that one aspect of the early response (induction of FUS1) is as defective as late responses (cell cycle arrest and projection formation). In contrast, another measure of the early response (induction of STE2) is normal. These data suggest that the biogenesis of a functional vacuole is necessary for optimal response to pheromone.

Overexpression of the STE4 gene leads to mating response in haploid Saccharomyces cerevisiae

1990 ◽  
Vol 10 (1) ◽  
pp. 217-222
Author(s):  
M Whiteway ◽  
L Hougan ◽  
D Y Thomas
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
G Protein ◽  
Gene Product ◽  
Beta Subunit ◽  
Yeast Cells ◽  
Pheromone Response ◽  
Mating Pheromone ◽  
Cycle Arrest

The STE4 gene of Saccharomyces cerevisiae encodes the beta subunit of the yeast pheromone receptor-coupled G protein. Overexpression of the STE4 protein led to cell cycle arrest of haploid cells. This arrest was like the arrest mediated by mating pheromones in that it led to similar morphological changes in the arrested cells. The arrest occurred in haploid cells of either mating type but not in MATa/MAT alpha diploids, and it was suppressed by defects in genes such as STE12 that are needed for pheromone response. Overexpression of the STE4 gene product also suppressed the sterility of cells defective in the mating pheromone receptors encoded by the STE2 and STE3 genes. Cell cycle arrest mediated by STE4 overexpression was prevented in cells that either were overexpressing the SCG1 gene product (the alpha subunit of the G protein) or lacked the STE18 gene product (the gamma subunit of the G protein). This finding suggests that in yeast cells, the beta subunit is the limiting component of the active beta gamma element and that a proper balance in the levels of the G-protein subunits is critical to a normal mating pheromone response.

scholarly journals Overexpression of the STE4 gene leads to mating response in haploid Saccharomyces cerevisiae.

1990 ◽  
Vol 10 (1) ◽  
pp. 217-222 ◽  
Author(s):  
M Whiteway ◽  
L Hougan ◽  
D Y Thomas
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
G Protein ◽  
Gene Product ◽  
Beta Subunit ◽  
Yeast Cells ◽  
Pheromone Response ◽  
Mating Pheromone ◽  
Cycle Arrest

The STE4 gene of Saccharomyces cerevisiae encodes the beta subunit of the yeast pheromone receptor-coupled G protein. Overexpression of the STE4 protein led to cell cycle arrest of haploid cells. This arrest was like the arrest mediated by mating pheromones in that it led to similar morphological changes in the arrested cells. The arrest occurred in haploid cells of either mating type but not in MATa/MAT alpha diploids, and it was suppressed by defects in genes such as STE12 that are needed for pheromone response. Overexpression of the STE4 gene product also suppressed the sterility of cells defective in the mating pheromone receptors encoded by the STE2 and STE3 genes. Cell cycle arrest mediated by STE4 overexpression was prevented in cells that either were overexpressing the SCG1 gene product (the alpha subunit of the G protein) or lacked the STE18 gene product (the gamma subunit of the G protein). This finding suggests that in yeast cells, the beta subunit is the limiting component of the active beta gamma element and that a proper balance in the levels of the G-protein subunits is critical to a normal mating pheromone response.

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 The ORC/Cdc6/MCM2-7 complex facilitates MCM2-7 dimerization during prereplicative complex formation

2013 ◽  
Vol 42 (4) ◽  
pp. 2257-2269 ◽  
Author(s):  
Cecile Evrin ◽  
Alejandra Fernández-Cid ◽  
Alberto Riera ◽  
Juergen Zech ◽  
Pippa Clarke ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Complex Formation ◽  
Cell Cycle Arrest ◽  
Atp Hydrolysis ◽  
Cycle Arrest ◽  
Helicase Loading ◽  
Limiting Step ◽  
Prereplicative Complex ◽  
Dominant Lethality

Abstract The replicative mini-chromosome-maintenance 2–7 (MCM2-7) helicase is loaded in Saccharomyces cerevisiae and other eukaryotes as a head-to-head double-hexamer around origin DNA. At first, ORC/Cdc6 recruits with the help of Cdt1 a single MCM2-7 hexamer to form an ‘initial’ ORC/Cdc6/Cdt1/MCM2-7 complex. Then, on ATP hydrolysis and Cdt1 release, the ‘initial’ complex is transformed into an ORC/Cdc6/MCM2-7 (OCM) complex. However, it remains unclear how the OCM is subsequently converted into a MCM2-7 double-hexamer. Through analysis of MCM2-7 hexamer-interface mutants we discovered a complex competent for MCM2-7 dimerization. We demonstrate that these MCM2-7 mutants arrest during prereplicative complex (pre-RC) assembly after OCM formation, but before MCM2-7 double-hexamer assembly. Remarkably, only the OCM complex, but not the ‘initial’ ORC/Cdc6/Cdt1/MCM2-7 complex, is competent for MCM2-7 dimerization. The MCM2-7 dimer, in contrast to the MCM2-7 double-hexamer, interacts with ORC/Cdc6 and is salt-sensitive, classifying the arrested complex as a helicase-loading intermediate. Accordingly, we found that overexpression of the mutants cause cell-cycle arrest and dominant lethality. Our work identifies the OCM complex as competent for MCM2-7 dimerization, reveals MCM2-7 dimerization as a limiting step during pre-RC formation and defines critical mechanisms that explain how origins are licensed.

scholarly journals Role of Cdc42-Cla4 Interaction in the Pheromone Response of Saccharomyces cerevisiae

2006 ◽  
Vol 6 (2) ◽  
pp. 317-327 ◽  
Author(s):  
Melanie Heinrich ◽  
Tim Köhler ◽  
Hans-Ulrich Mösch
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Map Kinase ◽  
Cell Cycle Arrest ◽  
Map Kinases ◽  
Negative Regulator ◽  
Cycle Arrest ◽  
Mitogen Activated Protein ◽  
Novel Alleles

ABSTRACT In Saccharomyces cerevisiae, the highly conserved Rho-type GTPase Cdc42 is essential for cell division and controls cellular development during mating and invasive growth. The role of Cdc42 in mating has been controversial, but a number of previous studies suggest that the GTPase controls the mitogen-activated protein (MAP) kinase cascade by activating the p21-activated protein kinase (PAK) Ste20. To further explore the role of Cdc42 in pheromone-stimulated signaling, we isolated novel alleles of CDC42 that confer resistance to pheromone. We find that in CDC42(V36A) and CDC42(V36A, I182T) mutant strains, the inability to undergo pheromone-induced cell cycle arrest correlates with reduced phosphorylation of the mating MAP kinases Fus3 and Kss1 and with a decrease in mating efficiency. Furthermore, Cdc42(V36A) and Cdc42(V36A, I182T) proteins show reduced interaction with the PAK Cla4 but not with Ste20. We also show that deletion of CLA4 in a CDC42(V36A, I182T) mutant strain suppresses pheromone resistance and that overexpression of CLA4 interferes with pheromone-induced cell cycle arrest and MAP kinase phosphorylation in CDC42 wild-type strains. Our data indicate that Cla4 has the potential to act as a negative regulator of the mating pathway and that this function of the PAK might be under control of Cdc42. In conclusion, our study suggests that control of pheromone signaling by Cdc42 not only depends on Ste20 but also involves interaction of the GTPase with Cla4.

Differential transmission of G1 cell cycle arrest and mating signals by Saccharomyces cerevisiae Ste5 mutants in the pheromone pathway

1999 ◽  
Vol 77 (5) ◽  
pp. 459-468
Author(s):  
You-Jeong Choi ◽  
Sun-Hong Kim ◽  
Ki-Sook Park ◽  
Kang-Yell Choi
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Signal Transduction ◽  
Cell Cycle Arrest ◽  
Mitogen Activated Protein Kinase ◽  
Chemical Mutagenesis ◽  
G1 Arrest ◽  
Cycle Arrest ◽  
Isolation And Characterization ◽  
G1 Cell Cycle Arrest

Saccharomyces cerevisiae Ste5 is a scaffold protein that recruits many pheromone signaling molecules to sequester the pheromone pathway from other homologous mitogen-activated protein kinase pathways. G1 cell cycle arrest and mating are two different physiological consequences of pheromone signal transduction and Ste5 is required for both processes. However, the roles of Ste5 in G1 arrest and mating are not fully understood. To understand the roles of Ste5 better, we isolated 150 G1 cell cycle arrest defective STE5 mutants by chemical mutagenesis of the gene. Here, we found that two G1 cell cycle arrest defective STE5 mutants (ste5MD248V and ste5delta-776) retained mating capacity. When overproduced in a wild-type strain, several ste5 mutants also showed different dominant phenotypes for G1 arrest and mating. Isolation and characterization of the mutants suggested separable roles of Ste5 in G1 arrest and mating of S. cerevisiae. In addition, the roles of Asp-248 and Tyr-421, which are important for pheromone signal transduction were further characterized by site-directed mutagenesis studies.Key words: Ste5, Saccharomyces cerevisiae, signal transduction, mating, G1 cell cycle arrest.

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