scholarly journals Temperature-Sensitive Lethal Pseudorevertants of ste Mutations in Saccharomyces cerevisiae

Genetics ◽  
1987 ◽  
Vol 115 (4) ◽  
pp. 627-636
Author(s):  
Margaret E Katz ◽  
Jill Ferguson ◽  
Steven I Reed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Complementation Group ◽  
Temperature Sensitive ◽  
G1 Arrest ◽  
Pheromone Response ◽  
Cycle Arrest ◽  
Homogeneous Cell ◽  
Complementation Groups ◽  
Mutant Cells

ABSTRACT A procedure was devised to isolate mutations that could restore conjugational competence to temperature sensitive ste mutants and simultaneously confer temperature-sensitive lethal growth phenotypes. Three such mutations, falling into two complementation groups, were identified on the basis of suppression of ste5 alleles. These same mutations were later shown to be capable of suppressing ste4 and ste7 alleles. Five mutations in a single complementation group were isolated as suppressors of ste2 alleles. None of the mutations described in this study conferred a homogeneous cell cycle arrest phenotype, and all were shown to define complementation groups distinct from those previously identified in studies of cell division cycle (cdc) mutations. In no instance did pseudoreversion appear to be achieved by mutational G1 arrest of ste mutant cells. Instead, it is proposed that the mutations restore conjugation by reestablishing the normal pheromone response.

scholarly journals A Yeast taf17 Mutant Requires the Swi6 Transcriptional Activator for Viability and Shows Defects in Cell Cycle-Regulated Transcription

Genetics ◽  
2000 ◽  
Vol 154 (4) ◽  
pp. 1561-1576
Author(s):  
Neil Macpherson ◽  
Vivien Measday ◽  
Lynda Moore ◽  
Brenda Andrews
Keyword(s):  
Cell Cycle ◽  
Transcriptional Activation ◽  
Essential Gene ◽  
Temperature Sensitive ◽  
Permissive Temperature ◽  
Synthetic Lethal ◽  
Cycle Arrest ◽  
A Cell ◽  
Allelism Tests ◽  
Complementation Groups

Abstract In Saccharomyces cerevisiae, the Swi6 protein is a component of two transcription factors, SBF and MBF, that promote expression of a large group of genes in the late G1 phase of the cell cycle. Although SBF is required for cell viability, SWI6 is not an essential gene. We performed a synthetic lethal screen to identify genes required for viability in the absence of SWI6 and identified 10 complementation groups of swi6-dependent lethal mutants, designated SLM1 through SLM10. We were most interested in mutants showing a cell cycle arrest phenotype; both slm7-1 swi6Δ and slm8-1 swi6Δ double mutants accumulated as large, unbudded cells with increased 1N DNA content and showed a temperature-sensitive growth arrest in the presence of Swi6. Analysis of the transcript levels of cell cycle-regulated genes in slm7-1 SWI6 mutant strains at the permissive temperature revealed defects in regulation of a subset of cyclin-encoding genes. Complementation and allelism tests showed that SLM7 is allelic with the TAF17 gene, which encodes a histone-like component of the general transcription factor TFIID and the SAGA histone acetyltransferase complex. Sequencing showed that the slm7-1 allele of TAF17 is predicted to encode a version of Taf17 that is truncated within a highly conserved region. The cell cycle and transcriptional defects caused by taf17slm7-1 are consistent with the role of TAFIIs as modulators of transcriptional activation and may reflect a role for TAF17 in regulating activation by SBF and MBF.

scholarly journals Requirement for TAFII250 Acetyltransferase Activity in Cell Cycle Progression

2000 ◽  
Vol 20 (4) ◽  
pp. 1134-1139 ◽  
Author(s):  
Elizabeth L. Dunphy ◽  
Theron Johnson ◽  
Scott S. Auerbach ◽  
Edith H. Wang
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Temperature Sensitive ◽  
Cycle Progression ◽  
Acetyltransferase Activity ◽  
Cycle Arrest ◽  
Protein Encoding ◽  
Acetyltransferase Domain ◽  
Mutant Cells

ABSTRACT The TATA-binding protein (TBP)-associated factor TAFII250 is the largest component of the basal transcription factor IID (TFIID). A missense mutation that maps to the acetyltransferase domain of TAFII250 induces the temperature-sensitive (ts) mutant hamster cell lines ts13 and tsBN462 to arrest in late G1. At the nonpermissive temperature (39.5°C), transcription from only a subset of protein encoding genes, including the G1 cyclins, is dramatically reduced in the mutant cells. Here we demonstrate that the ability of the ts13 allele of TAFII250 to acetylate histones in vitro is temperature sensitive suggesting that this enzymatic activity is compromised at 39.5°C in the mutant cells. Mutagenesis of a putative acetyl coenzyme A binding site produced a TAFII250 protein that displayed significantly reduced histone acetyltransferase activity but retained TBP and TAFII150 binding. Expression of this mutant in ts13 cells was unable to complement the cell cycle arrest or transcriptional defect observed at 39.5°C. These data suggest that TAFII250 acetyltransferase activity is required for cell cycle progression and regulates the expression of essential proliferative control genes.

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.

scholarly journals Temperature-sensitive cdc7 mutations of Saccharomyces cerevisiae are suppressed by the DBF4 gene, which is required for the G1/S cell cycle transition.

Genetics ◽  
1992 ◽  
Vol 131 (1) ◽  
pp. 21-29 ◽  
Author(s):  
K Kitada ◽  
L H Johnston ◽  
T Sugino ◽  
A Sugino
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Genomic Library ◽  
Temperature Sensitive ◽  
Multicopy Plasmid ◽  
Amino Acid Residues ◽  
Reading Frame ◽  
Allele Specific ◽  
Cell Cycle Transition ◽  
Mutant Cells

Abstract When present on a multicopy plasmid, a gene from a Saccharomyces cerevisiae genomic library suppresses the temperature-sensitive cdc7-1 mutation. The gene was identified as DBF4, which was previously isolated by complementation in dbf4-1 mutant cells and is required for the G1----S phase progression of the cell cycle. DBF4 has an open reading frame encoding 695 amino acid residues and the predicted molecular mass of the gene product is 80 kD. The suppression is allele-specific because a CDC7 deletion is not suppressed by DBF4. Suppression is mitosis-specific and the sporulation defect of cdc7 mutations is not suppressed by DBF4. Conversely, CDC7 on a multicopy plasmid suppresses the dbf4-1, -2, -3 and -4 mutations but not dbf4-5 and DBF4 deletion mutations. Furthermore, cdc7 mutations are incompatible with the temperature-sensitive dbf4 mutations. These results suggest that the CDC7 and DBF4 polypeptides interact directly or indirectly to permit initiation of yeast chromosome replication.

Mutations in cell division cycle genes CDC36 and CDC39 activate the Saccharomyces cerevisiae mating pheromone response pathway

1990 ◽  
Vol 10 (6) ◽  
pp. 2966-2972
Author(s):  
M de Barros Lopes ◽  
J Y Ho ◽  
S I Reed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
G Protein ◽  
G1 Arrest ◽  
Restrictive Temperature ◽  
Gene Products ◽  
Pheromone Response ◽  
Mating Pheromone ◽  
Pheromone Response Pathway ◽  
Mutational Activation

Conditional mutations in the genes CDC36 and CDC39 cause arrest in the G1 phase of the Saccharomyces cerevisiae cell cycle at the restrictive temperature. We present evidence that this arrest is a consequence of a mutational activation of the mating pheromone response. cdc36 and cdc39 mutants expressed pheromone-inducible genes in the absence of pheromone and conjugated in the absence of a mating pheromone receptor. On the other hand, cells lacking the G beta subunit or overproducing the G alpha subunit of the transducing G protein that couples the receptor to the pheromone response pathway prevented constitutive activation of the pathway in cdc36 and cdc39 mutants. These epistasis relationships imply that the CDC36 and CDC39 gene products act at the level of the transducing G protein. The CDC36 and CDC39 gene products have a role in cellular processes other than the mating pheromone response. A mating-type heterozygous diploid cell, homozygous for either the cdc36 or cdc39 mutation, does not exhibit the G1 arrest phenotype but arrests asynchronously with respect to the cell cycle. A similar asynchronous arrest was observed in cdc36 and cdc39 cells where the pheromone response pathway had been inactivated by mutations in the transducing G protein. Furthermore, cdc36 and cdc39 mutants, when grown on carbon catabolite-derepressing medium, did not arrest in G1 and did not induce pheromone-specific genes at the restrictive temperature.

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.

scholarly journals Removal of a Single α-Tubulin Gene Intron Suppresses Cell Cycle Arrest Phenotypes of Splicing Factor Mutations in Saccharomyces cerevisiae

2002 ◽  
Vol 22 (3) ◽  
pp. 801-815 ◽  
Author(s):  
C. Geoffrey Burns ◽  
Ryoma Ohi ◽  
Sapna Mehta ◽  
Eileen T. O’Toole ◽  
Mark Winey ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Cell Cycle Control ◽  
Mrna Splicing ◽  
Temperature Sensitive ◽  
Cycle Arrest ◽  
Indirect Consequence ◽  
Tubulin Protein ◽  
Cell Cycle Block

ABSTRACT Genetic and biochemical studies of Schizosaccharomyces pombe and Saccharomyces cerevisiae have identified gene products that play essential functions in both pre-mRNA splicing and cell cycle control. Among these are the conserved, Myb-related CDC5 (also known as Cef1p in S. cerevisiae) proteins. The mechanism by which loss of CDC5/Cef1p function causes both splicing and cell cycle defects has been unclear. Here we provide evidence that cell cycle arrest in a new temperature-sensitive CEF1 mutant, cef1-13, is an indirect consequence of defects in pre-mRNA splicing. Although cef1-13 cells harbor global defects in pre-mRNA splicing discovered through intron microarray analysis, inefficient splicing of the α-tubulin-encoding TUB1 mRNA was considered as a potential cause of the cef1-13 cell cycle arrest because cef1-13 cells arrest uniformly at G2/M with many hallmarks of a defective microtubule cytoskeleton. Consistent with this possibility, cef1-13 cells possess reduced levels of total TUB1 mRNA and α-tubulin protein. Removing the intron from TUB1 in cef1-13 cells boosts TUB1 mRNA and α-tubulin expression to near wild-type levels and restores microtubule stability in the cef1-13 mutant. As a result, cef1-13 tub1Δi cells progress through mitosis and their cell cycle arrest phenotype is alleviated. Removing the TUB1 intron from two other splicing mutants that arrest at G2/M, prp17Δ and prp22-1 strains, permits nuclear division, but suppression of the cell cycle block is less efficient. Our data raise the possibility that although cell cycle arrest phenotypes in prp mutants can be explained by defects in pre-mRNA splicing, the transcript(s) whose inefficient splicing contributes to cell cycle arrest is likely to be prp mutant dependent.

scholarly journals Mutations in cell division cycle genes CDC36 and CDC39 activate the Saccharomyces cerevisiae mating pheromone response pathway.

1990 ◽  
Vol 10 (6) ◽  
pp. 2966-2972 ◽  
Author(s):  
M de Barros Lopes ◽  
J Y Ho ◽  
S I Reed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
G Protein ◽  
G1 Arrest ◽  
Restrictive Temperature ◽  
Gene Products ◽  
Pheromone Response ◽  
Mating Pheromone ◽  
Pheromone Response Pathway ◽  
Mutational Activation

Conditional mutations in the genes CDC36 and CDC39 cause arrest in the G1 phase of the Saccharomyces cerevisiae cell cycle at the restrictive temperature. We present evidence that this arrest is a consequence of a mutational activation of the mating pheromone response. cdc36 and cdc39 mutants expressed pheromone-inducible genes in the absence of pheromone and conjugated in the absence of a mating pheromone receptor. On the other hand, cells lacking the G beta subunit or overproducing the G alpha subunit of the transducing G protein that couples the receptor to the pheromone response pathway prevented constitutive activation of the pathway in cdc36 and cdc39 mutants. These epistasis relationships imply that the CDC36 and CDC39 gene products act at the level of the transducing G protein. The CDC36 and CDC39 gene products have a role in cellular processes other than the mating pheromone response. A mating-type heterozygous diploid cell, homozygous for either the cdc36 or cdc39 mutation, does not exhibit the G1 arrest phenotype but arrests asynchronously with respect to the cell cycle. A similar asynchronous arrest was observed in cdc36 and cdc39 cells where the pheromone response pathway had been inactivated by mutations in the transducing G protein. Furthermore, cdc36 and cdc39 mutants, when grown on carbon catabolite-derepressing medium, did not arrest in G1 and did not induce pheromone-specific genes at the restrictive temperature.

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