scholarly journals The Asexual Yeast Candida glabrata Maintains Distinct a and α Haploid Mating Types

2008 ◽  
Vol 7 (5) ◽  
pp. 848-858 ◽  
Author(s):  
Héloïse Muller ◽  
Christophe Hennequin ◽  
Julien Gallaud ◽  
Bernard Dujon ◽  
Cécile Fairhead
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Type Strain ◽  
Candida Glabrata ◽  
Sexual Cycle ◽  
Mating Types ◽  
Differential Splicing ◽  
Mating Pheromone ◽  
Pheromone Receptor ◽  
Mating Pheromones ◽  
Key Genes

ABSTRACT The genome of the type strain of Candida glabrata (CBS138, ATCC 2001) contains homologs of most of the genes involved in mating in Saccharomyces cerevisiae, starting with the mating pheromone and receptor genes. Only haploid cells are ever isolated, but C. glabrata strains of both mating types are commonly found, the type strain being MATα and most other strains, such as BG2, being MAT a. No sexual cycle has been documented for this species. In order to understand which steps of the mating pathway are defective, we have analyzed the expression of homologs of some of the key genes involved as well as the production of mating pheromones and the organism's sensitivity to artificial pheromones. We show that cells of opposite mating types express both pheromone receptor genes and are insensitive to pheromones. Nonetheless, cells maintain specificity through regulation of the α1 and α2 genes and, more surprisingly, through differential splicing of the a 1 transcript.

scholarly journals Mutations in a gene encoding the alpha subunit of a Saccharomyces cerevisiae G protein indicate a role in mating pheromone signaling.

1988 ◽  
Vol 8 (6) ◽  
pp. 2484-2493 ◽  
Author(s):  
K Y Jahng ◽  
J Ferguson ◽  
S I Reed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
G Protein ◽  
Genomic Library ◽  
Negative Impact ◽  
Receptor Gene ◽  
Temperature Sensitive ◽  
Specific Cell ◽  
Protein Activity ◽  
Mating Pheromone ◽  
Pheromone Receptor

Mutations which allowed conjugation by Saccharomyces cerevisiae cells lacking a mating pheromone receptor gene were selected. One of the genes defined by such mutations was isolated from a yeast genomic library by complementation of a temperature-sensitive mutation and is identical to the gene GPA1 (also known as SCG1), recently shown to be highly homologous to genes encoding the alpha subunits of mammalian G proteins. Physiological analysis of temperature-sensitive gpa1 mutations suggests that the encoded G protein is involved in signaling in response to mating pheromones. Mutational disruption of G-protein activity causes cell-cycle arrest in G1, deposition of mating-specific cell surface agglutinins, and induction of pheromone-specific mRNAs, all of which are responses to pheromone in wild-type cells. In addition, mutants can conjugate without the benefit of mating pheromone or pheromone receptor. A model is presented where the activated G protein has a negative impact on a constitutive signal which normally keeps the pheromone response repressed.

Inhibition of Ty1 transposition by mating pheromones in Saccharomyces cerevisiae

1991 ◽  
Vol 11 (5) ◽  
pp. 2736-2743
Author(s):  
H Xu ◽  
J D Boeke
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Yeast Cells ◽  
Mating Pheromone ◽  
Yeast Saccharomyces Cerevisiae ◽  
Transposition Frequency ◽  
Mating Pheromones ◽  
Retroviral Replication ◽  
Viruslike Particles

The Ty1 elements in the yeast Saccharomyces cerevisiae are a family of retrotransposons which transpose via a process similar to that of retroviral replication. We report here that the Ty1 transposition process can be blocked posttranscriptionally by treatment of cells with mating pheromones. When haploid yeast cells are treated with appropriate mating pheromones, the transposition frequency of a marked Ty1 element driven by the GAL1 promoter is greatly diminished. Ty1 viruslike particles (VLPs), the putative intermediates for transposition, can be isolated from mating pheromone-treated cells. These VLPs accumulate to normal levels but are aberrant in that they produce very few reverse transcripts of Ty1 RNA both in vivo and in vitro and contain subnormal amounts of p90-TYB and related proteins. In addition, a TYA phosphoprotein product accumulates in treated cells, and some species of TYB proteins have decreased stability. We also show that decreased transposition in mating pheromone-treated cells is not a consequence of simply blocking cell division, since Ty1 transposes at a nearly normal rate in yeast cells arrested in G2 by the drug nocodazole.

scholarly journals Inhibition of Ty1 transposition by mating pheromones in Saccharomyces cerevisiae.

1991 ◽  
Vol 11 (5) ◽  
pp. 2736-2743 ◽  
Author(s):  
H Xu ◽  
J D Boeke
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Yeast Cells ◽  
Mating Pheromone ◽  
Yeast Saccharomyces Cerevisiae ◽  
Transposition Frequency ◽  
Mating Pheromones ◽  
Retroviral Replication ◽  
Viruslike Particles

The Ty1 elements in the yeast Saccharomyces cerevisiae are a family of retrotransposons which transpose via a process similar to that of retroviral replication. We report here that the Ty1 transposition process can be blocked posttranscriptionally by treatment of cells with mating pheromones. When haploid yeast cells are treated with appropriate mating pheromones, the transposition frequency of a marked Ty1 element driven by the GAL1 promoter is greatly diminished. Ty1 viruslike particles (VLPs), the putative intermediates for transposition, can be isolated from mating pheromone-treated cells. These VLPs accumulate to normal levels but are aberrant in that they produce very few reverse transcripts of Ty1 RNA both in vivo and in vitro and contain subnormal amounts of p90-TYB and related proteins. In addition, a TYA phosphoprotein product accumulates in treated cells, and some species of TYB proteins have decreased stability. We also show that decreased transposition in mating pheromone-treated cells is not a consequence of simply blocking cell division, since Ty1 transposes at a nearly normal rate in yeast cells arrested in G2 by the drug nocodazole.

scholarly journals Identification and characterization of a mutation affecting the division arrest signaling of the pheromone response pathway in Saccharomyces cerevisiae.

Genetics ◽  
1990 ◽  
Vol 124 (2) ◽  
pp. 275-282 ◽  
Author(s):  
H Fujimura
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Fusion ◽  
Morphological Changes ◽  
Mating Types ◽  
Cell Cycles ◽  
Morphological Alterations ◽  
Mating Pheromones ◽  
Cycle Arrest ◽  
Sterile Mutant

Abstract Mating pheromones, a- and alpha-factors, arrest the division of cells of opposite mating types, alpha and a cells, respectively. I have isolated a sterile mutant of Saccharomyces cerevisiae that is defective in division arrest in response to alpha-factor but not defective in morphological changes and agglutinin induction. The mutation was designated dac2 for division arrest control by mating pheromones. The dac2 mutation was closely linked to gal1 and was different from the previously identified cell type nonspecific sterile mutations (ste4, ste5, ste7, ste11, ste12, ste18 and dac1). Although dac2 cells had no phenotype in the absence of pheromones, they showed morphological alterations and divided continuously in the presence of pheromones. As a result, dac2 cells had a mating defect. The dac2 mutation could suppress the lethality caused by the disruption of the GPA1 gene (previously shown to encode a protein with similarity to the alpha subunit of mammalian G proteins). In addition, dac2 cells formed prezygotes with wild-type cells of opposite mating types, although they could not undergo cell fusion. These results suggest that the DAC2 product may control the signal for G-protein-mediated cell-cycle arrest and indicate that the synchronization of haploid yeast cell cycles by mating pheromones is essential for cell fusion during conjugation.

Mating-defective ste mutations are suppressed by cell division cycle start mutations in Saccharomyces cerevisiae

1982 ◽  
Vol 2 (9) ◽  
pp. 1052-1063
Author(s):  
J R Shuster
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Temperature Characteristic ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Gene Products ◽  
Wild Type ◽  
Mating Pheromone ◽  
Yeast Saccharomyces Cerevisiae ◽  
Mating Pheromones

Temperature-sensitive mutants which arrest in the G1 phase of the cell cycle have been described for the yeast Saccharomyces cerevisiae. One class of these mutants (carrying cdc28, cdc36, cdc37, or cdc39) forms a shmoo morphology at restrictive temperature, characteristic of mating pheromone-arrested wild-type cells. Therefore, one hypothesis to explain the control of cell division by mating factors states that mating pheromones arrest wild-type cells by inactivating one or more of these CDC gene products. A class of mutants (carrying ste4, ste5, ste7, ste11, or ste12) which is insensitive to mating pheromone and sterile has also been described. One possible function of the STE gene products is the inactivation of the CDC gene products in the presence of a mating pheromone. A model incorporating these two hypotheses predicts that such STE gene products will not be required for mating in strains carrying an appropriate cdc lesion. This prediction was tested by assaying the mating abilities of double mutants for all of the pairwise combinations of cdc and ste mutations. Lesions in either cdc36 or cdc39 suppressed the mating defect due to ste4 and ste5. Allele specificity was observed in the suppression of both ste4 and ste5. The results indicate that the CDC36, CDC39, STE4, and STE5 gene products interact functionally or physically or both in the regulation of cell division mediated by the presence or absence of mating pheromones. The cdc36 and cdc39 mutations did not suppress ste7, ste11, or ste12. Lesions in cdc28 or cdc37 did not suppress any of the ste mutations. Other models of CDC and STE gene action which predicted that some of the cdc and ste mutations would be alleles of the same locus were tested. None of the cdc mutations was allelic to the ste mutations and, therefore, these models were eliminated.

scholarly journals Self-Redirection of Metabolic Flux toward Squalene and Ethanol Pathways by Engineered Yeast

Metabolites ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 56
Author(s):  
Robina Manzoor ◽  
Maqbool Ahmed ◽  
Naveeda Riaz ◽  
Bushra Hafeez Kiani ◽  
Ullah Kaleem ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Transcription Factor ◽  
Type Strain ◽  
Lipid Droplets ◽  
Metabolic Flux ◽  
Wild Type Strain ◽  
Wild Type ◽  
Fusel Alcohol ◽  
Engineered Yeast ◽  
Key Genes

We have previously reported that squalene overproducing yeast self-downregulate the expression of the ethanol pathway (non-essential pathway) to divert the metabolic flux to the squalene pathway. In this study, the effect of co-production of squalene and ethanol on other non-essential pathways (fusel alcohol pathway, FA) of Saccharomyces cerevisiae was evaluated. However, before that, 13 constitutive promoters, like IRA1p, PET9p, RHO1p, CMD1p, ATP16p, USA3p, RER2p, COQ1p, RIM1p, GRS1p, MAK5p, and BRN1p, were engineered using transcription factor bindings sites from strong promoters HHF2p (−300 to −669 bp) and TEF1p (−300 to −579 bp), and employed to co-overexpress squalene and ethanol pathways in S. cerevisiae. The FSE strain overexpressing the key genes of the squalene pathway accumulated 56.20 mg/L squalene, a 16.43-fold higher than wild type strain (WS). The biogenesis of lipid droplets was stimulated by overexpressing DGA1 and produced 106 mg/L squalene in the FSE strain. AFT1p and CTR1p repressible promoters were also characterized and employed to downregulate the expression of ERG1, which also enhanced the production of squalene in FSE strain up to 42.85- (148.67 mg/L) and 73.49-fold (255.11 mg/L) respectively. The FSE strain was further engineered by overexpressing the key genes of the ethanol pathway and produced 40.2 mg/mL ethanol in the FSE1 strain, 3.23-fold higher than the WS strain. The FSE1 strain also self-downregulated the expression of the FA pathway up to 73.9%, perhaps by downregulating the expression of GCN4 by 2.24-fold. We demonstrate the successful tuning of the strength of yeast promoters and highest coproduction of squalene and ethanol in yeast, and present GCN4 as a novel metabolic regulator that can be manipulated to divert the metabolic flux from the non-essential pathway to engineered pathways.

scholarly journals Mating-defective ste mutations are suppressed by cell division cycle start mutations in Saccharomyces cerevisiae.

1982 ◽  
Vol 2 (9) ◽  
pp. 1052-1063 ◽  
Author(s):  
J R Shuster
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Temperature Characteristic ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Gene Products ◽  
Wild Type ◽  
Mating Pheromone ◽  
Yeast Saccharomyces Cerevisiae ◽  
Mating Pheromones

Temperature-sensitive mutants which arrest in the G1 phase of the cell cycle have been described for the yeast Saccharomyces cerevisiae. One class of these mutants (carrying cdc28, cdc36, cdc37, or cdc39) forms a shmoo morphology at restrictive temperature, characteristic of mating pheromone-arrested wild-type cells. Therefore, one hypothesis to explain the control of cell division by mating factors states that mating pheromones arrest wild-type cells by inactivating one or more of these CDC gene products. A class of mutants (carrying ste4, ste5, ste7, ste11, or ste12) which is insensitive to mating pheromone and sterile has also been described. One possible function of the STE gene products is the inactivation of the CDC gene products in the presence of a mating pheromone. A model incorporating these two hypotheses predicts that such STE gene products will not be required for mating in strains carrying an appropriate cdc lesion. This prediction was tested by assaying the mating abilities of double mutants for all of the pairwise combinations of cdc and ste mutations. Lesions in either cdc36 or cdc39 suppressed the mating defect due to ste4 and ste5. Allele specificity was observed in the suppression of both ste4 and ste5. The results indicate that the CDC36, CDC39, STE4, and STE5 gene products interact functionally or physically or both in the regulation of cell division mediated by the presence or absence of mating pheromones. The cdc36 and cdc39 mutations did not suppress ste7, ste11, or ste12. Lesions in cdc28 or cdc37 did not suppress any of the ste mutations. Other models of CDC and STE gene action which predicted that some of the cdc and ste mutations would be alleles of the same locus were tested. None of the cdc mutations was allelic to the ste mutations and, therefore, these models were eliminated.

Mutations in a gene encoding the alpha subunit of a Saccharomyces cerevisiae G protein indicate a role in mating pheromone signaling

1988 ◽  
Vol 8 (6) ◽  
pp. 2484-2493
Author(s):  
K Y Jahng ◽  
J Ferguson ◽  
S I Reed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
G Protein ◽  
Genomic Library ◽  
Negative Impact ◽  
Receptor Gene ◽  
Temperature Sensitive ◽  
Specific Cell ◽  
Protein Activity ◽  
Mating Pheromone ◽  
Pheromone Receptor

Mutations which allowed conjugation by Saccharomyces cerevisiae cells lacking a mating pheromone receptor gene were selected. One of the genes defined by such mutations was isolated from a yeast genomic library by complementation of a temperature-sensitive mutation and is identical to the gene GPA1 (also known as SCG1), recently shown to be highly homologous to genes encoding the alpha subunits of mammalian G proteins. Physiological analysis of temperature-sensitive gpa1 mutations suggests that the encoded G protein is involved in signaling in response to mating pheromones. Mutational disruption of G-protein activity causes cell-cycle arrest in G1, deposition of mating-specific cell surface agglutinins, and induction of pheromone-specific mRNAs, all of which are responses to pheromone in wild-type cells. In addition, mutants can conjugate without the benefit of mating pheromone or pheromone receptor. A model is presented where the activated G protein has a negative impact on a constitutive signal which normally keeps the pheromone response repressed.

scholarly journals Functional analysis of the interaction between Afr1p and the Cdc12p septin, two proteins involved in pheromone-induced morphogenesis.

1997 ◽  
Vol 8 (6) ◽  
pp. 987-998 ◽  
Author(s):  
L Giot ◽  
J B Konopka
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Functional Analysis ◽  
Cell Growth ◽  
Cell Fusion ◽  
Binding Domain ◽  
Temperature Sensitive ◽  
Receptor Signaling ◽  
Pheromone Receptor ◽  
Mating Pheromones ◽  
Mating Projection

Saccharomyces cerevisiae mating pheromones induce production of Afr1p, a protein that negatively regulates pheromone receptor signaling and is required for normal formation of the projection of cell growth that becomes the site of cell fusion during conjugation. Afr1p interacts with Cdc12p, which belongs to a family of filament-forming proteins termed septins that have been studied primarily for their role in bud morphogenesis and cytokinesis. The significance of the interaction between Afr1p and Cdc12p was tested in this study by examining the effects of AFR1 mutations that destroy the Cdc12p-binding domain. The results demonstrate that sequences in the C-terminal half of Afr1p are required for interaction with Cdc12p and for proper localization of Afr1p to the base of the mating projection. However, the Cdc12p-binding domain was not required for regulation of receptor signaling or for mating projection formation. This result was surprising because cells carrying a temperature-sensitive cdc12-6 mutation were defective in projection formation, indicating a role for Cdc12p in this process. Although the Cdc12p-binding domain was no essential for Afr1p function, this domain did improve the ability of Afr1p to promote morphogenesis, suggesting that the proper localization of Afr1p is important for its function.

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