Barrier Activity in Candida albicans Mediates Pheromone Degradation and Promotes Mating

ABSTRACT Mating in Candida albicans and Saccharomyces cerevisiae is regulated by the secretion of peptide pheromones that initiate the mating process. An important regulator of pheromone activity in S. cerevisiae is barrier activity, involving an extracellular aspartyl protease encoded by the BAR1 gene that degrades the alpha pheromone. We have characterized an equivalent barrier activity in C. albicans and demonstrate that the loss of C. albicans BAR1 activity results in opaque a cells exhibiting hypersensitivity to alpha pheromone. Hypersensitivity to pheromone is clearly seen in halo assays; in response to alpha pheromone, a lawn of C. albicans Δbar1 mutant cells produces a marked zone in which cell growth is inhibited, whereas wild-type strains fail to show halo formation. C. albicans mutants lacking BAR1 also exhibit a striking mating defect in a cells, but not in α cells, due to overstimulation of the response to alpha pheromone. The block to mating occurs prior to cell fusion, as very few mating zygotes were observed in mixes of Δbar1 a and α cells. Finally, in a barrier assay using a highly pheromone-sensitive strain, we were able to demonstrate that barrier activity in C. albicans is dependent on Bar1p. These studies reveal that a barrier activity to alpha pheromone exists in C. albicans and that the activity is analogous to that caused by Bar1p in S. cerevisiae.

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SELECTIVE ABORTION OF TWO NONSISTER NUCLEI IN A DEVELOPING ASCUS OF THE hfd1—1 MUTANT IN SACCHAROMYCES CEREVISIAE

Genetics ◽

10.1093/genetics/99.2.197 ◽

1981 ◽

Vol 99 (2) ◽

pp. 197-209

Author(s):

Susumu Okamoto ◽

Tetsuo Iino

Keyword(s):

Saccharomyces Cerevisiae ◽

Mutant Strain ◽

Recessive Mutation ◽

Microscopical Examination ◽

Wild Type ◽

Selective Abortion ◽

Dyad Analysis ◽

Mutant Cells ◽

Type Strains ◽

Light Microscopical Examination

ABSTRACT A recessive mutation, hfd1—1, in strain SOS4 of Saccharomyces cerevisiae leads the mutant cells to produce predominantly two-spored asci. Light microscopical examination of Giemsastained cells revealed no significant differences in the meiotic figures between mutant and wild-type strains. However, only two of the four meiotic products in a developing ascus matured to ascospores in SOS4. Dyad analysis was carried out on an hfd1-1 mutant strain heterozygous for three markers, asp5, gal1 and arg4, which are closely linked to their centromeres, and for his4, which is loosely linked to its centromere. The twospored asci produced by the hfd1—1 mutant segregated dominant (+) and recessive (-) alleles of each marker in a 1:1 ratio; they generally contained one + and one - spore for any given marker. The occurrence of rare dyads with two + or two - spores can be explained quantitatively by recombination between the marker and its centromere. From the results of these cytological and genetical analyses, we infer that, in the mutant strain, one genome set is partitioned to each of the four second-meiotic division poles, but only two nonsister genomes are incorporated into mature spores. Thus, the hfd1—1 mutation in SOS4 blocks incorporation of two nonsister nuclei into mature ascospores, but does not block enclosure of the remaining two nonsister nuclei.

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Yeast dom34 Mutants Are Defective in Multiple Developmental Pathways and Exhibit Decreased Levels of Polyribosomes

Genetics ◽

10.1093/genetics/149.1.45 ◽

1998 ◽

Vol 149 (1) ◽

pp. 45-56

Author(s):

Luther Davis ◽

JoAnne Engebrecht

Keyword(s):

Saccharomyces Cerevisiae ◽

Cell Cycle ◽

Heterologous Expression ◽

Protein Translation ◽

Developmental Pathways ◽

G1 Phase ◽

Growth Defect ◽

Wild Type ◽

Drosophila Homolog ◽

Mutant Cells

Abstract The DOM34 gene of Saccharomyces cerevisiae is similar togenes found in diverse eukaryotes and archaebacteria. Analysis of dom34 strains shows that progression through the G1 phase of the cell cycle is delayed, mutant cells enter meiosis aberrantly, and their ability to form pseudohyphae is significantly diminished. RPS30A, which encodes ribosomal protein S30, was identified in a screen for high-copy suppressors of the dom34Δ growth defect. dom34Δ mutants display an altered polyribosome profile that is rescued by expression of RPS30A. Taken together, these data indicate that Dom34p functions in protein translation to promote G1 progression and differentiation. A Drosophila homolog of Dom34p, pelota, is required for the proper coordination of meiosis and spermatogenesis. Heterologous expression of pelota in dom34Δ mutants restores wild-type growth and differentiation, suggesting conservation of function between the eukaryotic members of the gene family.

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Influences of Histone Stoichiometry on the Target Site Preference of Retrotransposons Ty1 and Ty2 in Saccharomyces cerevisiae

Genetics ◽

10.1093/genetics/142.3.761 ◽

1996 ◽

Vol 142 (3) ◽

pp. 761-776 ◽

Cited By ~ 2

Author(s):

Lori A Rinckel ◽

David J Garfinkel

Keyword(s):

Saccharomyces Cerevisiae ◽

Promoter Region ◽

Target Site ◽

Site Preference ◽

Wild Type ◽

Histone Proteins ◽

Protein Levels ◽

In The Wild ◽

Type Strains ◽

Orientation Bias

Abstract In Saccharomyces cerevisiae, the target site specificity of the retrotransposon Ty1 appears to involve the Ty integration complex recognizing chromatin structures. To determine whether changes in chromatin structure affect Ty1 and Ty2 target site preference, we analyzed Ty transposition at the CAN1 locus in mutants containing altered levels of histone proteins. A Δhta1-htb1 mutant with decreased levels of H2A and H2B histone proteins showed a pattern of Ty1 and Ty2 insertions at CAN1 that was significantly different from that of both the wild-type and a Δhta2-htb2 mutant, which does not have altered histone protein levels. Altered levels of H2A and H2B proteins disrupted a dramatic orientation bias in the CAN1 promoter region. In the wild-type strains, few Ty1 and Ty2 insertions in the promoter region were oriented opposite to the direction of CAN1 transcription. In the Δhta1-htb1 background, however, numerous Ty1 and Ty2 insertions were in the opposite orientation clustered within the TATA region. This altered insertion pattern does not appear to be due to a bias caused by selecting canavanine resistant isolates in the different HTA1-HTB1 backgrounds. Our results suggest that reduced levels of histone proteins alter Ty target site preference and disrupt an asymmetric Ty insertion pattern.

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CaNdt80 Is Involved in Drug Resistance in Candida albicans by Regulating CDR1

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.48.12.4505-4512.2004 ◽

2004 ◽

Vol 48 (12) ◽

pp. 4505-4512 ◽

Cited By ~ 66

Author(s):

Chia-Geun Chen ◽

Yun-Liang Yang ◽

Hsin-I Shih ◽

Chia-Li Su ◽

Hsiu-Jung Lo

Keyword(s):

Saccharomyces Cerevisiae ◽

Drug Resistance ◽

Candida Albicans ◽

Type Strain ◽

Antifungal Agents ◽

Wild Type Strain ◽

Efflux Pump ◽

Antifungal Drugs ◽

Galactosidase Activity ◽

Wild Type

ABSTRACT Overexpression of CDR1, an efflux pump, is one of the major mechanisms contributing to drug resistance in Candida albicans. CDR1 p-lacZ was constructed and transformed into a Saccharomyces cerevisiae strain so that the lacZ gene could be used as the reporter to monitor the activity of the CDR1 promoter. Overexpression of CaNDT80, the C. albicans homolog of S. cerevisiae NDT80, increases the β-galactosidase activity of the CDR1 p-lacZ construct in S. cerevisiae. Furthermore, mutations in CaNDT80 abolish the induction of CDR1 expression by antifungal agents in C. albicans. Consistently, the Candt80/Candt80 mutant is also more susceptible to antifungal drugs than the wild-type strain. Thus, the gene for CaNdt80 may be the first gene among the regulatory factors involved in drug resistance in C. albicans whose function has been identified.

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CSE4 Genetically Interacts With the Saccharomyces cerevisiae Centromere DNA Elements CDE I and CDE II but Not CDE III: Implications for the Path of the Centromere DNA Around a Cse4p Variant Nucleosome

Genetics ◽

10.1093/genetics/156.3.973 ◽

2000 ◽

Vol 156 (3) ◽

pp. 973-981

Author(s):

Kevin C Keith ◽

Molly Fitzgerald-Hayes

Keyword(s):

Saccharomyces Cerevisiae ◽

Chromosome Loss ◽

Structural Studies ◽

Wild Type ◽

Histone Fold ◽

Histone Fold Domain ◽

Histone H3 Variant ◽

Dna Elements ◽

Mutant Cells ◽

Loss Rates

Abstract Each Saccharomyces cerevisiae chromosome contains a single centromere composed of three conserved DNA elements, CDE I, II, and III. The histone H3 variant, Cse4p, is an essential component of the S. cerevisiae centromere and is thought to replace H3 in specialized nucleosomes at the yeast centromere. To investigate the genetic interactions between Cse4p and centromere DNA, we measured the chromosome loss rates exhibited by cse4 cen3 double-mutant cells that express mutant Cse4 proteins and carry chromosomes containing mutant centromere DNA (cen3). When compared to loss rates for cells carrying the same cen3 DNA mutants but expressing wild-type Cse4p, we found that mutations throughout the Cse4p histone-fold domain caused surprisingly large increases in the loss of chromosomes carrying CDE I or CDE II mutant centromeres, but had no effect on chromosomes with CDE III mutant centromeres. Our genetic evidence is consistent with direct interactions between Cse4p and the CDE I-CDE II region of the centromere DNA. On the basis of these and other results from genetic, biochemical, and structural studies, we propose a model that best describes the path of the centromere DNA around a specialized Cse4p-nucleosome.

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Mild temperature shock alters the transcription of a discrete class of Saccharomyces cerevisiae genes

Molecular and Cellular Biology ◽

10.1128/mcb.3.3.457-465.1983 ◽

1983 ◽

Vol 3 (3) ◽

pp. 457-465

Author(s):

C H Kim ◽

J R Warner

Keyword(s):

Saccharomyces Cerevisiae ◽

Ribosomal Protein ◽

Ribosomal Proteins ◽

Temperature Shift ◽

Restrictive Temperature ◽

Ribosomal Protein Genes ◽

Wild Type ◽

Temperature Shock ◽

Mild Temperature ◽

Mutant Cells

In Saccharomyces cerevisiae the synthesis of ribosomal proteins declines temporarily after a culture has been subjected to a mild temperature shock, i.e., a shift from 23 to 36 degrees C, each of which support growth. Using cloned genes for several S. cerevisiae ribosomal proteins, we found that the changes in the synthesis of ribosomal proteins parallel the changes in the concentration of mRNA of each. The disappearance and reappearance of the mRNA is due to a brief but severe inhibition of the transcription of each of the ribosomal protein genes, although the total transcription of mRNA in the cells is relatively unaffected by the temperature shock. The precisely coordinated response of these genes, which are scattered throughout the genome, suggests that either they or the enzyme which transcribes them has unique properties. In certain S. cerevisiae mutants, the synthesis of ribosomal proteins never recovers from a temperature shift. Yet both the decline and the resumption of transcription of these genes during the 30 min after the temperature shift are indistinguishable from those in wild-type cells. The failure of the mutant cells to grow at the restrictive temperature appears to be due to their inability to process the RNA transcribed from genes which have introns (Rosbash et al., Cell 24:679-686, 1981), a large proportion of which appear to be ribosomal protein genes.

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Farnesyl cysteine C-terminal methyltransferase activity is dependent upon the STE14 gene product in Saccharomyces cerevisiae

Molecular and Cellular Biology ◽

10.1128/mcb.10.10.5071-5076.1990 ◽

1990 ◽

Vol 10 (10) ◽

pp. 5071-5076

Author(s):

C A Hrycyna ◽

S Clarke

Keyword(s):

Saccharomyces Cerevisiae ◽

Cysteine Residue ◽

Peptide Sequence ◽

Direct Result ◽

Wild Type ◽

Methyltransferase Activity ◽

Ras Protein ◽

Carboxyl Methyltransferase ◽

C Terminus ◽

Mutant Cells

Membrane extracts of sterile Saccharomyces cerevisiae strains containing the a-specific ste14 mutation lack a farnesyl cysteine C-terminal carboxyl methyltransferase activity that is present in wild-type a and alpha cells. Other a-specific sterile strains with ste6 and ste16 mutations also have wild-type levels of the farnesyl cysteine carboxyl methyltransferase activity. This enzyme activity, detected by using a synthetic peptide sequence based on the C-terminus of a ras protein, may be responsible not only for the essential methylation of the farnesyl cysteine residue of a mating factor, but also for the methylation of yeast RAS1 and RAS2 proteins and possibly other polypeptides with similar C-terminal structures. We demonstrate that the farnesylation of the cysteine residue in the peptide is required for the methyltransferase activity, suggesting that methyl esterification follows the lipidation reaction in the cell. To show that the loss of methyltransferase activity is a direct result of the ste14 mutation, we transformed ste14 mutant cells with a plasmid complementing the mating defect of this strain and found that active enzyme was produced. Finally, we demonstrated that a similar transformation of cells possessing the wild-type STE14 gene resulted in sixfold overproduction of the enzyme. Although more complicated possibilities cannot be ruled out, these results suggest that STE14 is a candidate for the structural gene for a methyltransferase involved in the formation of isoprenylated cysteine alpha-methyl ester C-terminal structures.

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Viability of clathrin heavy-chain-deficient Saccharomyces cerevisiae is compromised by mutations at numerous loci: implications for the suppression hypothesis.

Molecular and Cellular Biology ◽

10.1128/mcb.11.8.3868 ◽

1991 ◽

Vol 11 (8) ◽

pp. 3868-3878 ◽

Cited By ~ 13

Author(s):

A L Munn ◽

L Silveira ◽

M Elgort ◽

G S Payne

Keyword(s):

Saccharomyces Cerevisiae ◽

Cell Growth ◽

Heavy Chain ◽

Secretory Pathway ◽

Genetic Locus ◽

Wild Type ◽

Site Mutation ◽

Gene Encoding ◽

Clathrin Heavy Chain ◽

Lethal Allele

The gene encoding clathrin heavy chain in Saccharomyces cerevisiae (CHC1) is not essential for growth in most laboratory strains tested. However, in certain genetic backgrounds, a deletion of CHC1 (chc1) results in cell death. Lethality in these chc1 strains is determined by a locus designated SCD1 (suppressor of clathrin deficiency) which is unlinked to CHC1 (S. K. Lemmon and E. W. Jones, Science 238:504-509, 1987). The lethal allele of SCD1 has no effect on cell growth when the wild-type version of CHC1 is present. This result led to the proposal that most yeast strains are viable in the absence of clathrin heavy chain because they possess the SCD1 suppressor. Discovery of another yeast strain that cannot grow without clathrin heavy chain has allowed us to perform a genetic test of the suppressor hypothesis. Genetic crosses show that clathrin-deficient lethality in the latter strain is conferred by a single genetic locus (termed CDL1, for clathrin-deficient lethality). By constructing strains in which CHC1 expression is regulated by the GAL10 promoter, we demonstrate that the lethal alleles of SCD1 and CDL1 are recessive. In both cases, very low expression of CHC1 can allow cells to escape from lethality. Genetic complementation and segregation analyses indicate that CDL1 and SCD1 are distinct genes. The lethal CDL1 allele does not cause a defect in the secretory pathway of either wild-type or clathrin heavy-chain-deficient yeast. A systematic screen to identify mutants unable to grow in the absence of clathrin heavy chain uncovered numerous genes similar to SCD1 and CDL1. These findings argue against the idea that viability of chc1 cells is due to genetic suppression, since this hypothesis would require the existence of a large number of unlinked genes, all of which are required for suppression. Instead, lethality appears to be a common, nonspecific occurrence when a second-site mutation arises in a strain whose cell growth is already severely compromised by the lack of clathrin heavy chain.

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Bioreduction of Some Common Carbonylic Compounds Mediated by Yeasts

Zeitschrift für Naturforschung C ◽

10.1515/znc-2010-1-201 ◽

2010 ◽

Vol 65 (1-2) ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Javier Silva ◽

Julio Alarcón ◽

Sergio A. Aguila ◽

Joel B. Alderete

Keyword(s):

Saccharomyces Cerevisiae ◽

Pichia Pastoris ◽

Aqueous Medium ◽

Ethyl Acetoacetate ◽

Enantiomeric Excess ◽

Optically Active ◽

Environmentally Benign ◽

Wild Type ◽

Regeneration System ◽

Type Strains

Bioreduction of several prochiral carbonylic compounds such as acetophenone (1), ethyl acetoacetate (2) and ethyl phenylpropionate (3) to the corresponding optically active secalcohols 1a - 3a was performed using wild-type strains of Pichia pastoris UBB 1500, Rhodotorula sp., and Saccharomyces cerevisiae. The reductions showed moderate to excellent conversion and high enantiomeric excess, in an extremely mild and environmentally benign manner in aqueous medium, using glucose as cofactor regeneration system. The obtained alcohols follow Prelog’s rule, but in the reduction of 1 with P. pastoris UBB 1500 the anti- Prelog enantiopreference was observed

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