scholarly journals Control of adaptation to mating pheromone by G protein beta subunits of Saccharomyces cerevisiae.

Genetics ◽  
1994 ◽  
Vol 138 (4) ◽  
pp. 1081-1092 ◽  
Author(s):  
A V Grishin ◽  
J L Weiner ◽  
K J Blumer
Keyword(s):  
Saccharomyces Cerevisiae ◽  
G Protein ◽  
Beta Subunit ◽  
Beta Subunits ◽  
G1 Arrest ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Repeat Units ◽  
Response And Recovery ◽  
In Cis

Abstract The STE4 gene of the yeast Saccharomyces cerevisiae encodes the beta subunit of a heterotrimeric G protein that mediates response to mating pheromones and influences recovery from pheromone-induced growth arrest. To explore how G beta subunits regulate response and recovery (adaptation), we isolated and characterized signaling-defective STE4 alleles (STE4sd). STE4sd mutations resulted in amino acid substitutions in the N-terminal region of Ste4p, proximal to the first of seven repeat units conserved in G protein beta subunits. Genetic tests indicated that STE4sd mutations disrupted functions of Ste4p required for inducing pheromone responses. Wild-type cells that overexpressed STE4sd alleles displayed apparently normal initial responses to pheromone as judged by quantitative mating, G1 arrest and transcriptional assays. However, after undergoing initial G1 arrest, wild-type cells overexpressing STE4sd alleles recovered more quickly from division arrest, suggestive of a hyperadaptive phenotype. Because hyperadaptation occurred when STE4sd alleles were overexpressed in cells lacking Sst1p (Bar1p), Sst2p or the C-terminal domain of the alpha-factor receptor, this phenotype did not involve three principal modes of adaptation in yeast. However, hyperadaptation was abolished when STE4sd mutations were combined in cis with a deletion that removes a segment of Ste4p (residues 310-346) previously implicated in adaptation to pheromone. These results indicate that G beta subunits possess two independent activities, one required for triggering pheromone response and another that promotes adaptation. Potential models for G beta subunit-mediated adaptation are discussed.

scholarly journals Nonrecombinant meiosis I nondisjunction in Saccharomyces cerevisiae induced by tRNA ochre suppressors.

Genetics ◽  
1989 ◽  
Vol 123 (1) ◽  
pp. 81-95 ◽  
Author(s):  
E J Louis ◽  
J E Haber
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitotic Chromosome ◽  
Stop Codon ◽  
Fold Increase ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Nonsense Mutations ◽  
Chromosome Iii ◽  
Meiosis I ◽  
Chromosome Nondisjunction

Abstract The presence of the tRNA ochre suppressors SUP11 and SUP5 is found to induce meiosis I nondisjunction in the yeast Saccharomyces cerevisiae. The induction increases with increasing dosage of the suppressor and decreases in the presence of an antisuppressor. The effect is independent of the chromosomal location of SUP11. Each of five different chromosomes monitored exhibited nondisjunction at frequencies of 0.1%-1.1% of random spores, which is a 16-160-fold increase over wild-type levels. Increased nondisjunction is reflected by a marked increase in tetrads with two and zero viable spores. In the case of chromosome III, for which a 50-cM map interval was monitored, the resulting disomes are all in the parental nonrecombinant configuration. Recombination along chromosome III appears normal both in meioses that have no nondisjunction and in meioses for which there was nondisjunction of another chromosome. We propose that a proportion of one or more proteins involved in chromosome pairing, recombination or segregation are aberrant due to translational read-through of the normal ochre stop codon. Hygromycin B, an antibiotic that can suppress nonsense mutations via translational read-through, also induces nonrecombinant meiosis I nondisjunction. Increases in mistranslation, therefore, increase the production of aneuploids during meiosis. There was no observable effect of SUP11 on mitotic chromosome nondisjunction; however some disomes caused SUP11 ade2-ochre strains to appear white or red, instead of pink.

scholarly journals Rsp5p, a New Link between the Actin Cytoskeleton and Endocytosis in the Yeast Saccharomyces cerevisiae

2002 ◽  
Vol 22 (20) ◽  
pp. 6946-6948 ◽  
Author(s):  
Joanna Kamińska ◽  
Beata Gajewska ◽  
Anita K. Hopper ◽  
Teresa ˙Zołądek
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Actin Cytoskeleton ◽  
Cytoskeletal Proteins ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Ww Domains ◽  
Ubiquitin Protein Ligase ◽  
Growth Defects ◽  
Genes Encoding ◽  
Cytoskeleton Dynamics

ABSTRACT Rsp5p is an ubiquitin-protein ligase of Saccharomyces cerevisiae that has been implicated in numerous processes including transcription, mitochondrial inheritance, and endocytosis. Rsp5p functions at multiple steps of endocytosis, including ubiquitination of substrates and other undefined steps. We propose that one of the roles of Rsp5p in endocytosis involves maintenance and remodeling of the actin cytoskeleton. We report the following. (i) There are genetic interactions between rsp5 and several mutant genes encoding actin cytoskeletal proteins. rsp5 arp2, rsp5 end3, and rsp5 sla2 double mutants all show synthetic growth defects. Overexpressed wild-type RSP5 or mutant rsp5 genes with lesions of some WW domains suppress growth defects of arp2 and end3 cells. The defects in endocytosis, actin cytoskeleton, and morphology of arp2 are also suppressed. (ii) Rsp5p and Sla2p colocalize in abnormal F-actin-containing clumps in arp2 and pan1 mutants. Immunoprecipitation experiments confirmed that Rsp5p and Act1p colocalize in pan1 mutants. (iii) Rsp5p and Sla2p coimmunoprecipitate and partially colocalize to punctate structures in wild-type cells. These studies provide the first evidence for an interaction of an actin cytoskeleton protein with Rsp5p. (iv) rsp5-w1 mutants are resistant to latrunculin A, a drug that sequesters actin monomers and depolymerizes actin filaments, consistent with the fact that Rsp5p is involved in actin cytoskeleton dynamics.

scholarly journals Spindle dynamics and cell cycle regulation of dynein in the budding yeast, Saccharomyces cerevisiae.

1995 ◽  
Vol 130 (3) ◽  
pp. 687-700 ◽  
Author(s):  
E Yeh ◽  
R V Skibbens ◽  
J W Cheng ◽  
E D Salmon ◽  
K Bloom
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nuclear Translocation ◽  
Spindle Pole ◽  
Cell Cortex ◽  
Wild Type ◽  
Immunofluorescent Localization ◽  
Yeast Saccharomyces Cerevisiae ◽  
Spindle Dynamics ◽  
Spindle Elongation ◽  
Anaphase B

We have used time-lapse digital- and video-enhanced differential interference contrast (DE-DIC, VE-DIC) microscopy to study the role of dynein in spindle and nuclear dynamics in the yeast Saccharomyces cerevisiae. The real-time analysis reveals six stages in the spindle cycle. Anaphase B onset appears marked by a rapid phase of spindle elongation, simultaneous with nuclear migration into the daughter cell. The onset and kinetics of rapid spindle elongation are identical in wild type and dynein mutants. In the absence of dynein the nucleus does not migrate as close to the neck as in wild-type cells and initial spindle elongation is confined primarily to the mother cell. Rapid oscillations of the elongating spindle between the mother and bud are observed in wild-type cells, followed by a slower growth phase until the spindle reaches its maximal length. This stage is protracted in the dynein mutants and devoid of oscillatory motion. Thus dynein is required for rapid penetration of the nucleus into the bud and anaphase B spindle dynamics. Genetic analysis reveals that in the absence of a functional central spindle (ndcl), dynein is essential for chromosome movement into the bud. Immunofluorescent localization of dynein-beta-galactosidase fusion proteins reveals that dynein is associated with spindle pole bodies and the cell cortex: with spindle pole body localization dependent on intact microtubules. A kinetic analysis of nuclear movement also revealed that cytokinesis is delayed until nuclear translocation is completed, indicative of a surveillance pathway monitoring nuclear transit into the bud.

scholarly journals Topoisomerase I involvement in illegitimate recombination in Saccharomyces cerevisiae.

1996 ◽  
Vol 16 (4) ◽  
pp. 1805-1812 ◽  
Author(s):  
J Zhu ◽  
R H Schiestl
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Aberrations ◽  
Topoisomerase I ◽  
Wild Type Strain ◽  
Hot Spot ◽  
Illegitimate Recombination ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae

Chromosome aberrations may cause cancer and many heritable diseases. Topoisomerase I has been suspected of causing chromosome aberrations by mediating illegitimate recombination. The effects of deletion and of overexpression of the topoisomerase I gene on illegitimate recombination in the yeast Saccharomyces cerevisiae have been studied. Yeast transformations were carried out with DNA fragments that did not have any homology to the genomic DNA. The frequency of illegitimate integration was 6- to 12-fold increased in a strain overexpressing topoisomerase I compared with that in isogenic control strains. Hot spot sequences [(G/C)(A/T)T] for illegitimate integration target sites accounted for the majority of the additional events after overexpression of topoisomerase I. These hot spot sequences correspond to sequences previously identified in vitro as topoisomerase I preferred cleavage sequences in other organisms. Furthermore, such hot spot sequences were found in 44% of the integration events present in the TOP1 wild-type strain and at a significantly lower frequency in the top1delta strain. Our results provide in vivo evidence that a general eukaryotic topoisomerase I enzyme nicks DNA and ligates nonhomologous ends, leading to illegitimate recombination.

Evolution of ethylene by Saccharomyces cerevisiae as influenced by the carbon source for growth and the presence of air

1978 ◽  
Vol 24 (6) ◽  
pp. 637-642 ◽  
Author(s):  
K. C. Thomas ◽  
Mary Spencer
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Carbon Source ◽  
Ethylene Production ◽  
Atp Synthesis ◽  
Yeast Cells ◽  
Yeast Culture ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Absolute Requirement ◽  
Wild Type Yeast

Effects of the carbon source and oxygen on ethylene production by the yeast Saccharomyces cerevisiae have been studied. The amounts of ethylene evolved by the yeast culture were less than those detected in the blank (an equal volume of uninoculated medium), suggesting a net absorption of ethylene by the yeast cells. Addition of glucose to the lactate-grown yeast culture induced ethylene production. This glucose-induced stimulation of ethylene production was inhibited to a great extent by cycloheximide. Results suggested that the yeast cells in the presence of glucose synthesized an ethylene precursor and passed it into the medium. The conversion of this precursor to ethylene might be stimulated by oxygen. The fact that ethylene was produced by the yeast growing anaerobically and also by respiration-deficient mutants isolated from the wild-type yeast suggested that mitochondrial ATP synthesis was not an absolute requirement for ethylene biogenesis.

scholarly journals Disruption of the RAD52 gene alters the spectrum of spontaneous SUP4-o mutations in Saccharomyces cerevisiae.

Genetics ◽  
1989 ◽  
Vol 122 (3) ◽  
pp. 535-542 ◽  
Author(s):  
B A Kunz ◽  
M G Peters ◽  
S E Kohalmi ◽  
J D Armstrong ◽  
M Glattke ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Base Pair ◽  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Mutator Phenotype ◽  
In The Wild ◽  
Single Base Pair ◽  
Almost All

Abstract Defects in the RAD52 gene of the yeast Saccharomyces cerevisiae confer a mutator phenotype. To characterize this effect in detail, a collection of 238 spontaneous SUP4-o mutations arising in a strain having a disrupted RAD52 gene was analyzed by DNA sequencing. The resulting mutational spectrum was compared to that derived from an examination of 222 spontaneous mutations selected in a nearisogenic wild-type (RAD52) strain. This comparison revealed that the mutator phenotype was associated with an increase in the frequency of base-pair substitutions. All possible types of substitution were detected but there was a reduction in the relative fraction of A.T----G.C transitions and an increase in the proportion of G.C----C.G transversions. These changes were sufficient to cause a twofold greater preference for substitutions at G.C sites in the rad52 strain despite a decrease in the fraction of G.C----T.A transversions. There were also considerable differences between the distributions of substitutions within the SUP4-o gene. Base-pair changes occurred at fewer sites in the rad52 strain but the mutated sites included several that were not detected in the RAD52 background. Only two of the four sites that were mutated most frequently in the rad52 strain were also prominent in the wild-type strain and mutation frequencies at almost all sites common to both strains were greater for the rad52 derivative. Although single base-pair deletions occurred in the two strains with similar frequencies, several classes of mutation that were recovered in the wild-type background including multiple base-pair deletions, insertions of the yeast transposable element Ty, and more complex changes, were not detected in the rad52 strain.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Ribosomal protein L30 is dispensable in the yeast Saccharomyces cerevisiae.

1990 ◽  
Vol 10 (10) ◽  
pp. 5235-5243 ◽  
Author(s):  
D M Baronas-Lowell ◽  
J R Warner
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ribosomal Protein ◽  
Ribosomal Proteins ◽  
Wild Type ◽  
Diploid Strain ◽  
Chain Reaction ◽  
Yeast Saccharomyces Cerevisiae ◽  
Ribosomal Subunits ◽  
Strong Homology ◽  
Polymerase Chain

In the yeast Saccharomyces cerevisiae, L30 is one of many ribosomal proteins that is encoded by two functional genes. We have cloned and sequenced RPL30B, which shows strong homology to RPL30A. Use of mRNA as a template for a polymerase chain reaction demonstrated that RPL30B contains an intron in its 5' untranslated region. This intron has an unusual 5' splice site, C/GUAUGU. The genomic copies of RPL30A and RPL30B were disrupted by homologous recombination. Growth rates, primer extension, and two-dimensional ribosomal protein analyses of these disruption mutants suggested that RPL30A is responsible for the majority of L30 production. Surprisingly, meiosis of a diploid strain carrying one disrupted RPL30A and one disrupted RPL30B yielded four viable spores. Ribosomes from haploid cells carrying both disrupted genes had no detectable L30, yet such cells grew with a doubling time only 30% longer than that of wild-type cells. Furthermore, depletion of L30 did not alter the ratio of 60S to 40S ribosomal subunits, suggesting that there is no serious effect on the assembly of 60S subunits. Polysome profiles, however, suggest that the absence of L30 leads to the formation of stalled translation initiation complexes.

scholarly journals Genome-Scale Analysis Reveals Sst2 as the Principal Regulator of Mating Pheromone Signaling in the Yeast Saccharomyces cerevisiae

2006 ◽  
Vol 5 (2) ◽  
pp. 330-346 ◽  
Author(s):  
Scott A. Chasse ◽  
Paul Flanary ◽  
Stephen C. Parnell ◽  
Nan Hao ◽  
Jiyoung Y. Cha ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Transition State ◽  
G Protein ◽  
Common Property ◽  
Rgs Proteins ◽  
Homologous Proteins ◽  
Yeast Saccharomyces Cerevisiae ◽  
Α Subunit ◽  
Pheromone Signaling

ABSTRACT A common property of G protein-coupled receptors is that they become less responsive with prolonged stimulation. Regulators of G protein signaling (RGS proteins) are well known to accelerate G protein GTPase activity and do so by stabilizing the transition state conformation of the G protein α subunit. In the yeast Saccharomyces cerevisiae there are four RGS-homologous proteins (Sst2, Rgs2, Rax1, and Mdm1) and two Gα proteins (Gpa1 and Gpa2). We show that Sst2 is the only RGS protein that binds selectively to the transition state conformation of Gpa1. The other RGS proteins also bind Gpa1 and modulate pheromone signaling, but to a lesser extent and in a manner clearly distinct from Sst2. To identify other candidate pathway regulators, we compared pheromone responses in 4,349 gene deletion mutants representing nearly all nonessential genes in yeast. A number of mutants produced an increase (sst2, bar1, asc1, and ygl024w) or decrease (cla4) in pheromone sensitivity or resulted in pheromone-independent signaling (sst2, pbs2, gas1, and ygl024w). These findings suggest that Sst2 is the principal regulator of Gpa1-mediated signaling in vivo but that other proteins also contribute in distinct ways to pathway regulation.

Ribosomal protein L30 is dispensable in the yeast Saccharomyces cerevisiae

1990 ◽  
Vol 10 (10) ◽  
pp. 5235-5243
Author(s):  
D M Baronas-Lowell ◽  
J R Warner
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ribosomal Protein ◽  
Ribosomal Proteins ◽  
Wild Type ◽  
Diploid Strain ◽  
Chain Reaction ◽  
Yeast Saccharomyces Cerevisiae ◽  
Ribosomal Subunits ◽  
Strong Homology ◽  
Polymerase Chain

In the yeast Saccharomyces cerevisiae, L30 is one of many ribosomal proteins that is encoded by two functional genes. We have cloned and sequenced RPL30B, which shows strong homology to RPL30A. Use of mRNA as a template for a polymerase chain reaction demonstrated that RPL30B contains an intron in its 5' untranslated region. This intron has an unusual 5' splice site, C/GUAUGU. The genomic copies of RPL30A and RPL30B were disrupted by homologous recombination. Growth rates, primer extension, and two-dimensional ribosomal protein analyses of these disruption mutants suggested that RPL30A is responsible for the majority of L30 production. Surprisingly, meiosis of a diploid strain carrying one disrupted RPL30A and one disrupted RPL30B yielded four viable spores. Ribosomes from haploid cells carrying both disrupted genes had no detectable L30, yet such cells grew with a doubling time only 30% longer than that of wild-type cells. Furthermore, depletion of L30 did not alter the ratio of 60S to 40S ribosomal subunits, suggesting that there is no serious effect on the assembly of 60S subunits. Polysome profiles, however, suggest that the absence of L30 leads to the formation of stalled translation initiation complexes.

scholarly journals Conservation of function and regulation within the Cdc28/cdc2 protein kinase family: characterization of the human Cdc2Hs protein kinase in Saccharomyces cerevisiae.

1989 ◽  
Vol 9 (9) ◽  
pp. 4064-4068 ◽  
Author(s):  
C Wittenberg ◽  
S I Reed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Yeast Strain ◽  
Cell Cycle Progression ◽  
G1 Arrest ◽  
Yeast Saccharomyces Cerevisiae ◽  
Environmental Signals ◽  
Transgenic Yeast ◽  
M Phase

Whereas the Cdc28 protein kinase of the budding yeast Saccharomyces cerevisiae plays an essential role in cell cycle progression during the G1 interval, a function in the progression from the G2 interval into M phase has been inferred for its homologs, including the Cdc2Hs protein kinase of humans. To better understand these apparently disparate roles, we constructed a yeast strain in which the resident CDC28 gene was replaced by its human homolog, CDC2Hs. This transgenic yeast strain was able to perform the G1 functions attributed to the Cdc28 protein kinase, including the ability to grow and divide normally, to respond to environmental signals that induce G1 arrest, and to regulate the Cdc2Hs protein kinase appropriately in response to these signals.

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