The Kar3-Interacting Protein Cik1p Plays a Critical Role in Passage Through Meiosis I in Saccharomyces cerevisiae

Genetics ◽  
2001 ◽  
Vol 159 (3) ◽  
pp. 939-951
Author(s):  
Robert M Q Shanks ◽  
Rebecca J Kamieniecki ◽  
Dean S Dawson
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cellular Localization ◽  
Critical Role ◽  
Chromosome Loss ◽  
Spore Viability ◽  
Interacting Protein ◽  
Associated Proteins ◽  
Synaptonemal Complex Formation ◽  
Mutant Cells ◽  
Meiosis I

Abstract Meiosis I in Saccharomyces cerevisiae is dependent upon the motor protein Kar3. Absence of Kar3p in meiosis results in an arrest in prophase I. Cik1p and Vik1p are kinesin-associated proteins known to modulate the function of Kar3p in the microtubule-dependent processes of karyogamy and mitosis. Experiments were performed to determine whether Cik1p and Vik1p are also important for the function of Kar3p during meiosis. The meiotic phenotypes of a cik1 mutant were found to be similar to those of kar3 mutants. Cells without Cik1p exhibit a meiotic defect in homologous recombination and synaptonemal complex formation. Most cik1 mutant cells, like kar3 mutants, arrest in meiotic prophase; however, in cik1 mutants this arrest is less severe. These data are consistent with the model that Cik1p is necessary for some, but not all, of the roles of Kar3p in meiosis I. vik1 mutants sporulate at wild-type levels, but have reduced spore viability. This loss in viability is partially attributable to vegetative chromosome loss in vik1 diploids. Cellular localization experiments reveal that Kar3p, Cik1p, and Vik1p are present throughout meiosis and are consistent with Cik1p and Vik1p having different meiotic roles.

scholarly journals 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 ◽  
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.

scholarly journals Aip3p/Bud6p, a yeast actin-interacting protein that is involved in morphogenesis and the selection of bipolar budding sites.

1997 ◽  
Vol 8 (4) ◽  
pp. 729-753 ◽  
Author(s):  
D C Amberg ◽  
J E Zahner ◽  
J W Mulholland ◽  
J R Pringle ◽  
D Botstein
Keyword(s):  
Coiled Coil ◽  
Interacting Protein ◽  
Cell Cycles ◽  
Division Site ◽  
Bud Emergence ◽  
C Terminus ◽  
Positional Marker ◽  
Associated Proteins ◽  
Sites Of Action ◽  
Mutant Cells

A search for Saccharomyces cerevisiae proteins that interact with actin in the two-hybrid system and a screen for mutants that affect the bipolar budding pattern identified the same gene, AIP3/BUD6. This gene is not essential for mitotic growth but is necessary for normal morphogenesis. MATa/alpha daughter cells lacking Aip3p place their first buds normally at their distal poles but choose random sites for budding in subsequent cell cycles. This suggests that actin and associated proteins are involved in placing the bipolar positional marker at the division site but not at the distal tip of the daughter cell. In addition, although aip3 mutant cells are not obviously defective in the initial polarization of the cytoskeleton at the time of bud emergence, they appear to lose cytoskeletal polarity as the bud enlarges, resulting in the formation of cells that are larger and rounder than normal. aip3 mutant cells also show inefficient nuclear migration and nuclear division, defects in the organization of the secretory system, and abnormal septation, all defects that presumably reflect the involvement of Aip3p in the organization and/or function of the actin cytoskeleton. The sequence of Aip3p is novel but contains a predicted coiled-coil domain near its C terminus that may mediate the observed homo-oligomerization of the protein. Aip3p shows a distinctive localization pattern that correlates well with its likely sites of action: it appears at the presumptive bud site prior to bud emergence, remains near the tips of small bund, and forms a ring (or pair of rings) in the mother-bud neck that is detectable early in the cell cycle but becomes more prominent prior to cytokinesis. Surprisingly, the localization of Aip3p does not appear to require either polarized actin or the septin proteins of the neck filaments.

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 Meiotic chromosome pairing in triploid and tetraploid Saccharomyces cerevisiae.

Genetics ◽  
1995 ◽  
Vol 139 (4) ◽  
pp. 1511-1520 ◽  
Author(s):  
J Loidl
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Complex Formation ◽  
Chromosome Segregation ◽  
Chromosome Pairing ◽  
Meiotic Chromosome ◽  
Low Frequency ◽  
Spore Viability ◽  
Homologous Chromosomes ◽  
Meiotic Chromosome Pairing ◽  
Synaptonemal Complex Formation

Abstract Meiotic chromosome pairing in isogenic triploid and tetraploid strains of yeast and the consequences of polyploidy on meiotic chromosome segregation are studied. Synaptonemal complex formation at pachytene was found to be different in the triploid and in the tetraploid. In the triploid, triple-synapsis, that is, the connection of three homologues at a given site, is common. It can even extend all the way along the chromosomes. In the tetraploid, homologous chromosomes mostly come in pairs of synapsed bivalents. Multiple synapsis, that is, synapsis of more than two homologues in one and the same region, was virtually absent in the tetraploid. About five quadrivalents per cell occurred due to the switching of pairing partners. From the frequency of pairing partner switches it can be deduced that in most chromosomes synapsis is initiated primarily at one end, occasionally at both ends and rarely at an additional intercalary position. In contrast to a considerably reduced spore viability (approximately 40%) in the triploid, spore viability is only mildly affected in the tetraploid. The good spore viability is presumably due to the low frequency of quadrivalents and to the highly regular 2:2 segregation of the few quadrivalents that do occur. Occasionally, however, quadrivalents appear to be subject to 3:1 nondisjunction that leads to spore death in the second generation.

scholarly journals Meiosis in Saccharomyces cerevisiae mutants lacking the centromere-binding protein CP1.

Genetics ◽  
1992 ◽  
Vol 131 (1) ◽  
pp. 43-53 ◽  
Author(s):  
D C Masison ◽  
R E Baker
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitotic Chromosome ◽  
Binding Protein ◽  
Pleiotropic Effect ◽  
Chromosome Loss ◽  
Spore Viability ◽  
Chromosome Fragments ◽  
Unpaired Chromosome ◽  
Yeast Meiosis ◽  
Chromosome I

Abstract CP1 (encoded by the CEP1 gene) is a centromere binding protein of Saccharomyces cerevisiae that binds to the conserved DNA element I (CDEI) of yeast centromeres. To investigate the function of CP1 in yeast meiosis, we analyzed the meiotic segregation of CEN plasmids, nonessential chromosome fragments (CFs) and chromosomes in cep1 null mutants. Plasmids and CFs missegregated in 10-20% of meioses with the most frequent type of aberrant event being precocious sister segregation at the first meiotic division; paired and unpaired CFs behaved similarly. An unpaired chromosome I homolog (2N + 1) also missegregated at high frequency in the cep1 mutant (7.6%); however, missegregation of other chromosomes was not detected by tetrad analysis. Spore viability of cep1 tetrads was significantly reduced, and the pattern of spore death was nonrandom. The inviability could not be explained solely by chromosome missegregation and is probably a pleiotropic effect of cep1. Mitotic chromosome loss in cep1 strains was also analyzed. Both simple loss (1:0 segregation) and nondisjunction (2:0 segregation) were increased, but the majority of loss events resulted from nondisjunction. We interpret the results to suggest that CP1 generally promotes chromatid-kinetochore adhesion.

scholarly journals Constitutive Signal Transduction by Mutant Ssy5p and Ptr3p Components of the SPS Amino Acid Sensor System in Saccharomyces cerevisiae

2005 ◽  
Vol 4 (6) ◽  
pp. 1116-1124 ◽  
Author(s):  
Peter Poulsen ◽  
Boqian Wu ◽  
Richard F. Gaber ◽  
Morten C. Kielland-Brandt
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acids ◽  
Transcription Factors ◽  
Plasma Membrane ◽  
Amino Acid ◽  
Amino Acid Permease ◽  
Associated Proteins ◽  
Amino Acid Sensing ◽  
Median Effective Concentration ◽  
Mutant Cells

ABSTRACT Amino acids in the environment of Saccharomyces cerevisiae can transcriptionally activate a third of the amino acid permease genes through a signal that originates from the interaction between the extracellular amino acids and an integral plasma membrane protein, Ssy1p. Two plasma membrane-associated proteins, Ptr3p and Ssy5p, participate in the sensing, which results in cleavage of the transcription factors Stp1p and Stp2p, removing 10 kDa of the N terminus of each of them. This confers the transcription factors with the ability to gain access to the nucleus and activate transcription of amino acid permease genes. To extend our understanding of the role of Ptr3p and Ssy5p in this amino acid sensing process, we have isolated constitutive gain-of-function mutants in these two components by using a genetic screening in which potassium uptake is made dependent on amino acid signaling. Mutants which exhibit inducer-independent processing of Stp1p and activation of the amino acid permease gene AGP1 were obtained. For each component of the SPS complex, constitutive signaling by a mutant allele depended on the presence of wild-type alleles of the other two components. Despite the signaling in the absence of inducer, the processing of Stp1p was more complete in the presence of inducer. Dose response assays showed that the median effective concentration for Stp1p processing in the mutant cells was decreased; i.e., a lower inducer concentration is needed for signaling in the mutant cells. These results suggest that the three sensor components interact intimately in a complex rather than in separate reactions and support the notion that the three components function as a complex.

scholarly journals Isolation of COM1, a New Gene Required to Complete Meiotic Double-Strand Break-Induced Recombination in Saccharomyces cerevisiae

Genetics ◽  
1997 ◽  
Vol 146 (3) ◽  
pp. 781-795 ◽  
Author(s):  
Susanne Prinz ◽  
Angelika Amon ◽  
Franz Klein
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Strand Break ◽  
Double Strand Breaks ◽  
Homologous Pairing ◽  
Yeast Saccharomyces Cerevisiae ◽  
Spore Viability ◽  
Strand Breaks ◽  
New Gene ◽  
Synaptonemal Complex Formation

We have designed a screen to isolate mutants defective during a specific part of meiotic prophase I of the yeast Saccharomyces cerevisiae. Genes required for the repair of meiotic double-strand breaks or for the separation of recombined chromosomes are targets of this mutant hunt. The specificity is achieved by selecting for mutants that produce viable spores when recombination and reductional segregation are prevented by mutations in SPO11 and SP013 genes, but fail to yield viable spores during a normal Rec+ meiosis. We have identified and characterized a mutation com1-1, which blocks processing of meiotic double-strand breaks and which interferes with synaptonemal complex formation, homologous pairing and, as a consequence, spore viability after induction of meiotic recombination. The COM1/SAE2 gene was cloned by complementation, and the deletion mutant has a phenotype similar to com1-1. com1/sae2 mutants closely resemble the phenotype of rad50S, as assayed by phase-contrast microscopy for spore formation, physical and genetic analysis of recombination, fluorescence in situ hybridization to quantify homologous pairing and immunofluorescence and electron microscopy to determine the capability to synapse axial elements.

Mechanisms of Nuclear Transport in the cell: RNA exosome in Saccharomyces cerevisiae

Bionatura ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 1423-1426
Author(s):  
Bruna Rech ◽  
Fernando A. Gonzales-Zubiate
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Catalytic Activity ◽  
Rna Processing ◽  
Cellular Localization ◽  
Nuclear Transport ◽  
Single Units ◽  
Yeast Saccharomyces Cerevisiae ◽  
Rna Transcripts ◽  
Non Coding Rnas ◽  
Rna Exosome

Ribonucleases (RNases) functions in the cell include precise maturation of non- coding RNAs and degradation of specific RNA transcripts that are no longer necessary. RNAses are present in the cell as single units or assembled as multimeric complexes; one of these complexes is the RNA exosome, a highly conserved complex essential for RNA processing and degradation. In the yeast Saccharomyces cerevisiae, the RNA exosome comprises eleven subunits, two with catalytic activity: Rrp6 and Rrp44, where the Rrp6 subunit is exclusively nuclear. Despite the RNA exosome has been intensively investigated since its discovery in 1997, only a few studies were accomplished concerning its nuclear transport. This review describes recent research about cellular localization and transport of this essential complex.

scholarly journals Functional expression, quantification and cellular localization of the Hxt2 hexose transporter of Saccharomyces cerevisiae tagged with the green fluorescent protein

1999 ◽  
Vol 339 (2) ◽  
pp. 299-307 ◽  
Author(s):  
Arthur L. KRUCKEBERG ◽  
Ling YE ◽  
Jan A. BERDEN ◽  
Karel van DAM
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Plasma Membrane ◽  
Green Fluorescent Protein ◽  
Glucose Transport ◽  
Cellular Localization ◽  
Fluorescent Protein ◽  
Hexose Transporter ◽  
High Concentrations ◽  
Green Fluorescent

The Hxt2 glucose transport protein of Saccharomyces cerevisiae was genetically fused at its C-terminus with the green fluorescent protein (GFP). The Hxt2-GFP fusion protein is a functional hexose transporter: it restored growth on glucose to a strain bearing null mutations in the hexose transporter genes GAL2 and HXT1 to HXT7. Furthermore, its glucose transport activity in this null strain was not markedly different from that of the wild-type Hxt2 protein. We calculated from the fluorescence level and transport kinetics that induced cells had 1.4×105 Hxt2-GFP molecules per cell, and that the catalytic-centre activity of the Hxt2-GFP molecule in vivo is 53 s-1 at 30 °C. Expression of Hxt2-GFP was induced by growth at low concentrations of glucose. Under inducing conditions the Hxt2-GFP fluorescence was localized to the plasma membrane. In a strain impaired in the fusion of secretory vesicles with the plasma membrane, the fluorescence accumulated in the cytoplasm. When induced cells were treated with high concentrations of glucose, the fluorescence was redistributed to the vacuole within 4 h. When endocytosis was genetically blocked, the fluorescence remained in the plasma membrane after treatment with high concentrations of glucose.

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.

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