scholarly journals The SPA2 gene of Saccharomyces cerevisiae is important for pheromone-induced morphogenesis and efficient mating.

1990 ◽  
Vol 111 (4) ◽  
pp. 1451-1464 ◽  
Author(s):  
S Gehrung ◽  
M Snyder
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Critical Role ◽  
Coiled Coil ◽  
Large Deletion ◽  
Yeast Cells ◽  
Mating Pheromone ◽  
Reading Frame ◽  
Distinct Cell ◽  
Polarized Cell Growth ◽  
Mutant Cells

Upon exposure to mating pheromone, Saccharomyces cerevisiae undergoes cellular differentiation to form a morphologically distinct cell called a "shmoo". Double staining experiments revealed that both the SPA2 protein and actin localize to the shmoo tip which is the site of polarized cell growth. Actin concentrates as spots throughout the shmoo projection, while SPA2 localizes as a sharp patch at the shmoo tip. DNA sequence analysis of the SPA2 gene revealed an open reading frame 1,466 codons in length; the predicted protein sequence contains many internal repeats including a nine amino acid sequence that is imperfectly repeated 25 times. Portions of the SPA2 sequence exhibit a low-level similarity to proteins containing coiled-coil structures. Yeast cells containing a large deletion of the SPA2 gene are similar in growth rate to wild-type cells. However, spa2 mutant cells are impaired in their ability to form shmoos upon exposure to mating pheromone, and they do not mate efficiently with other spa2 mutant cells. Thus, we suggest that the SPA2 protein plays a critical role in cellular morphogenesis during mating, perhaps as a cytoskeletal protein.

scholarly journals Pex17p of Saccharomyces cerevisiae Is a Novel Peroxin and Component of the Peroxisomal Protein Translocation Machinery

1998 ◽  
Vol 140 (1) ◽  
pp. 49-60 ◽  
Author(s):  
Bettina Huhse ◽  
Peter Rehling ◽  
Markus Albertini ◽  
Lars Blank ◽  
Karl Meller ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Translocation ◽  
Coiled Coil ◽  
Matrix Proteins ◽  
Peroxisomal Membrane ◽  
Trimeric Complex ◽  
Peroxisomal Targeting ◽  
Targeting Signal ◽  
Membrane Spanning ◽  
Mutant Cells

The Saccharomyces cerevisiae pex17-1 mutant was isolated from a screen to identify mutants defective in peroxisome biogenesis. pex17-1 and pex17 null mutants fail to import matrix proteins into peroxisomes via both PTS1- and PTS2-dependent pathways. The PEX17 gene (formerly PAS9; Albertini, M., P. Rehling, R. Erdmann, W. Girzalsky, J.A.K.W. Kiel, M. Veenhuis, and W.-H Kunau. 1997. Cell. 89:83–92) encodes a polypeptide of 199 amino acids with one predicted membrane spanning region and two putative coiled-coil structures. However, localization studies demonstrate that Pex17p is a peripheral membrane protein located at the surface of peroxisomes. Particulate structures containing the peroxisomal integral membrane proteins Pex3p and Pex11p are evident in pex17 mutant cells, indicating the existence of peroxisomal remnants (“ghosts”). This finding suggests that pex17 null mutant cells are not impaired in peroxisomal membrane biogenesis. Two-hybrid studies showed that Pex17p directly binds to Pex14p, the recently proposed point of convergence for the two peroxisomal targeting signal (PTS)-dependent import pathways, and indirectly to Pex5p, the PTS1 receptor. The latter interaction requires Pex14p, indicating the potential of these three peroxins to form a trimeric complex. This conclusion is supported by immunoprecipitation experiments showing that Pex14p and Pex17p coprecipitate with both PTS receptors in the absence of Pex13p. From these and other studies we conclude that Pex17p, in addition to Pex13p and Pex14p, is the third identified component of the peroxisomal translocation machinery.

scholarly journals Vid24p, a Novel Protein Localized to the Fructose-1,6-bisphosphatase–containing Vesicles, Regulates Targeting of Fructose-1,6-bisphosphatase from the Vesicles to the Vacuole for Degradation

1998 ◽  
Vol 140 (6) ◽  
pp. 1347-1356 ◽  
Author(s):  
Meng-Chieh Chiang ◽  
Hui-Ling Chiang
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Membrane Protein ◽  
Critical Role ◽  
Carbon Sources ◽  
Degradation Pathway ◽  
Yeast Cells ◽  
Fructose 1,6 Bisphosphatase ◽  
Peripheral Membrane Protein ◽  
Gluconeogenic Enzyme ◽  
Novel Protein

Glucose regulates the degradation of the key gluconeogenic enzyme, fructose-1,6-bisphosphatase (FBPase), in Saccharomyces cerevisiae. FBPase is targeted from the cytosol to a novel type of vesicle, and then to the vacuole for degradation when yeast cells are transferred from medium containing poor carbon sources to fresh glucose. To identify proteins involved in the FBPase degradation pathway, we cloned our first VID (vacuolar import and degradation) gene. The VID24 gene was identified by complementation of the FBPase degradation defect of the vid24-1 mutant. Vid24p is a novel protein of 41 kD and is synthesized in response to glucose. Vid24p is localized to the FBPase-containing vesicles as a peripheral membrane protein. In the absence of functional Vid24p, FBPase accumulates in the vesicles and fails to move to the vacuole, suggesting that Vid24p regulates FBPase targeting from the vesicles to the vacuole. FBPase sequestration into the vesicles is not affected in the vid24-1 mutant, indicating that Vid24p acts after FBPase sequestration into the vesicles has occurred. Vid24p is the first protein identified that marks the FBPase-containing vesicles and plays a critical role in delivering FBPase from the vesicles to the vacuole for degradation.

scholarly journals Identification and analysis of a Saccharomyces cerevisiae copper homeostasis gene encoding a homeodomain protein.

1994 ◽  
Vol 14 (12) ◽  
pp. 7792-7804 ◽  
Author(s):  
S A Knight ◽  
K T Tamai ◽  
D J Kosman ◽  
D J Thiele
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Carbon Source ◽  
Sole Carbon Source ◽  
Copper Resistance ◽  
Yeast Cells ◽  
Homeodomain Protein ◽  
Mrna Levels ◽  
Reading Frame ◽  
Cup1 Gene ◽  
Intracellular Copper

Yeast metallothionein, encoded by the CUP1 gene, and its copper-dependent transcriptional activator ACE1 play a key role in mediating copper resistance in Saccharomyces cerevisiae. Using an ethyl methanesulfonate mutant of a yeast strain in which CUP1 and ACE1 were deleted, we isolated a gene, designated CUP9, which permits yeast cells to grow at high concentrations of environmental copper, most notably when lactate is the sole carbon source. Disruption of CUP9, which is located on chromosome XVI, caused a loss of copper resistance in strains which possessed CUP1 and ACE1, as well as in the cup1 ace1 deletion strain. Measurement of intracellular copper levels of the wild-type and cup9-1 mutant demonstrated that total intracellular copper concentrations were unaffected by CUP9. CUP9 mRNA levels were, however, down regulated by copper when yeast cells were grown with glucose but not with lactate or glycerol-ethanol as the sole carbon source. This down regulation was independent of the copper metalloregulatory transcription factor ACE1. The DNA sequence of CUP9 predicts an open reading frame of 306 amino acids in which a 55-amino-acid sequence showed 47% identity with the homeobox domain of the human proto-oncogene PBX1, suggesting that CUP9 is a DNA-binding protein which regulates the expression of important copper homeostatic genes.

scholarly journals Comparison of thermosensitive alleles of the CDC25 gene involved in the cAMP metabolism of Saccharomyces cerevisiae.

Genetics ◽  
1990 ◽  
Vol 124 (4) ◽  
pp. 797-806 ◽  
Author(s):  
A Petitjean ◽  
F Hilger ◽  
K Tatchell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gene Product ◽  
Critical Role ◽  
Missense Mutations ◽  
Nucleotide Exchange ◽  
Carboxy Terminus ◽  
Reading Frame ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Carboxy Terminal

Abstract The CDC25 gene from Saccharomyces cerevisiae is an essential component of the RAS-adenylate cyclase pathway. Genetic and biochemical evidence has led to the proposal that the gene product may act upstream of RAS, possibly as a guanine nucleotide exchange factor. We report here the cloning, sequencing and characterization of four mutations in the CDC25 gene. All four are missense mutations which reside within the carboxy-terminal quarter of the single open reading frame found within the gene. Three of the four are missense mutations in the same amino acid codon. A search of protein data bases reveals that the carboxy terminus of the putative CDC25 gene product is similar to that of LTE1, a gene required for growth at low temperature and SCD25, a suppressor of cdc25. Taken together these data indicate that the carboxy terminus of CDC25 plays a critical role in the function of the CDC25 gene product and that other proteins, such as LTE1 or SCD25, may have related activities.

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.

scholarly journals A Saccharomyces cerevisiae Mutant Lacking a K+/H+ Exchanger

1998 ◽  
Vol 180 (22) ◽  
pp. 5860-5865 ◽  
Author(s):  
Jorge Ramírez ◽  
Oscar Ramírez ◽  
Carlos Saldaña ◽  
Roberto Coria ◽  
Antonio Peña
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Core Protein ◽  
Kinetic Studies ◽  
Flow Cytometry Analysis ◽  
Wild Type ◽  
Reading Frame ◽  
Duplication Rate ◽  
Significant Difference ◽  
Internal Ph ◽  
Mutant Cells

ABSTRACT The KHA1 gene corresponding to the open reading frame YJL094c (2.62 kb) encoding a putative K+/H+antiporter (873 amino acids) in Saccharomyces cerevisiaewas disrupted by homologous recombination. The core protein is similar to the putative Na+/H+ antiporters fromEnterococcus hirae (NAPA gene) andLactococcus lactis (LLUPP gene) and the putative K+/H+ exchanger from Escherichia coli (KEFC gene). Disruption of the KHA1gene resulted in an increased K+ accumulation and net influx without a significant difference in efflux, as well as an increased growth rate, smaller cells, and twice the cell yield per glucose used. Flow cytometry analysis showed an increase of the DNA duplication rate in the mutant. Kinetic studies of86Rb+ uptake showed the same saturable system for wild-type and disruptant strains. Mutant cells also produced a greater acidification of the medium coincident with an internal pH alkalinization and showed a higher oxygen consumption velocity. We speculate that higher K+ accumulation and increased osmotic pressure accelerate the cell cycle and metabolic activity.

Transcriptional derepression of the Saccharomyces cerevisiae HSP26 gene during heat shock

1990 ◽  
Vol 10 (12) ◽  
pp. 6362-6373
Author(s):  
R E Susek ◽  
S Lindquist
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Heat Shock ◽  
Transcriptional Control ◽  
Critical Role ◽  
Constitutive Expression ◽  
Small Heat Shock Protein ◽  
Yeast Cells ◽  
Heat Shock Gene ◽  
General Mechanism ◽  
Regulatory Sequences

hsp26, the small heat shock protein of Saccharomyces cerevisiae, accumulates in response to heat and other types of stress. It also accumulates during the normal course of development, as cells enter stationary phase growth or begin to sporulate (S. Kurtz, J. Rossi, L. Petko, and S. Lindquist, Science 231:1154-1157, 1986). Analysis of deletion and insertion mutations demonstrated that transcriptional control plays a critical role in regulating HSP26 expression. The HSP26 promoter was found to be complex and appears to contain repressing elements as well as activating elements. Several upstream deletion mutations resulted in strong constitutive expression of HSP26. Furthermore, upstream sequences from the HSP26 gene repressed the constitutive expression of a heterologous heat shock gene. We propose that basal repression and heat-induced depression of transcription play major roles in regulating the expression of HSP26. None of the recombinant constructs that we analyzed separated cis-regulatory sequences responsible for heat shock regulation from those responsible for developmental regulation of HSP26. Depression of HSP26 transcription may be the general mechanism of HSP26 induction in yeast cells. This regulatory scheme is very different from that described for the regulation of most other heat shock genes.

Extramitochondrial citrate synthase activity in bakers' yeast

1986 ◽  
Vol 6 (2) ◽  
pp. 488-493
Author(s):  
T M Rickey ◽  
A S Lewin
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Citrate Synthase ◽  
Glucose Repression ◽  
Yeast Cells ◽  
Mitochondrial Enzyme ◽  
Wild Type ◽  
Reading Frame ◽  
Leu2 Gene ◽  
Growth Requirements ◽  
Wild Type Yeast

We isolated the gene for citrate synthase (citrate oxaloacetate lyase; EC 4.1.3.7) from Saccharomyces cerevisiae and ablated it by inserting the yeast LEU2 gene within its reading frame. This revealed a second, nonmitochondrial citrate synthase. Like the mitochondrial enzyme, this enzyme was sensitive to glucose repression. It did not react with antibodies against mitochondrial citrate synthase. Haploid cells lacking a gene for mitochondrial citrate synthase grew somewhat slower than wild-type yeast cells, but exhibited no auxotrophic growth requirements.

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.

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