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At least 109 records · Page 6Linked to original sources
PubMed2007

Norovirus capsid protein expressed in yeast forms virus-like particles and stimulates systemic and mucosal immunity in mice following an oral administration of raw yeast extracts.

Norovirus (NV) gastroenteritis is a widespread disease affecting people of all ages worldwide. A simple, safe, and easily deliverable vaccine may be the key for the control and prevention of NV gastroenteritis. In this study, we demonstrated that a NV recombinant capsid protein (strain VA387, genogroup II.4) expressed in yeast (Pichia pastoris) spontaneously formed virus-like particles (VLPs) like those expressed in other in vitro systems. Oral administration of raw material from the yeast cell lysates containing 0.1 mg of VLPs without an adjuvant resulted in systemic and mucosal immune responses in mice. Significantly higher and earlier responses were observed in mice receiving a higher dose (1 mg per dose) of the antigen. Both the serum and fecal antibodies blocked VA387 VLP binding to its histo-blood group antigen receptors. The animals did not reveal any side effect following the administration of the yeast lysates. Our results indicated that yeast is a simple, effective alternative for NV VLP production. The mice immunization study also indicated that the oral administration of raw yeast extracts without an adjuvant is a safe and simple way which is worth to be studied for vaccine delivery in humans.

Administration, Oral↗
PubMed1992

Antibodies directed against a yeast carboxyl-terminal peroxisomal targeting signal specifically recognize peroxisomal proteins from various yeasts.

The carboxyl-terminal tripeptide Ala-Lys-Ile is essential for targeting Candida tropicalis trifunctional enzyme (hydratase-dehydrogenase-epimerase) to peroxisomes of both Candida albicans and Saccharomyces cerevisiae (Aitchison,J.D., Murray, W.W. and Rachubinski, R. A. (1991).J. Biol. Chem. 266, 23197-23203). We investigated the possibility that this tripeptide may act as a general peroxisomal targeting signal (PTS) for other proteins in the yeasts C. tropicalis, C. albicans, Yarrowia lipolytica and S. cerevisiae, and in rat liver. Anti-AKI antibodies raised against the carboxyl-terminal 12 amino acids of trifunctional enzyme were used to search for this PTS in proteins of these yeasts and of rat liver. The anti-AKI antibodies reacted exclusively with multiple peroxisomal proteins from the yeasts C. tropicalis, C. albicans and Y. lipolytica. There was a weak reaction of the antibodies with one peroxisomal protein from S. cerevisiae and no reaction with peroxisomal proteins from rat liver. Antibodies directed against a synthetic peptide containing a carboxyl-terminal Ser-Lys-Leu PTS (Gould, S. J., Krisans, S., Keller, G.-A. and Subramani, S. (1990). J. Cell Biol. 110,27-34) reacted with multiple peroxisomal proteins of rat liver and with peroxisomal proteins of yeast distinct from those identified with anti-AKI antibodies. These results provide evidence that several peroxisomal proteins of different yeasts contain a PTS antigenically similar to that of C. tropicalis trifunctional enzyme and that this signal is absent from peroxisomal proteins from at least one mammalian system, rat liver.

Amino Acid Sequence↗
PubMed2006

Interactions between yeasts and grapevines: filamentous growth, endopolygalacturonase and phytopathogenicity of colonizing yeasts.

It has been clearly established that phytopathogenic fungi, bacteria, and viruses exert biotic stresses on plants. Much less is known, however, about the interactions between enological species of yeast and their host plants. In a previous study, we described how Saccharomyces cerevisiae, the most common enological yeast, can act as a grapevine (Vitis vinifera L.) pathogen, causing growth retardation or plant death. In the present in vitro study on 11 strains of yeast belonging to different genera, which often occur on the surfaces of vineyard grapes and V. vinifera, a link was found to exist between strain phytopathogenecity and pseudohyphal growth habits and/or endopolygalacturonase activity. The results obtained here are consistent with earlier findings showing that the phytopathogenicity of yeast strains depends on the filamentous growth process, and show that endopolygalacturonase alone is not responsible for the invasion of plants tissues. The mechanisms observed here may be of significant ecological importance and may help to explain the long periods of yeast survival found to occur in vineyards.

Ecosystem↗
PubMed1996

Identification of COUP-TFII as a peroxisome proliferator response element binding factor using genetic selection in yeast: COUP-TFII activates transcription in yeast but antagonizes PPAR signaling in mammalian cells.

Peroxisome proliferator-response elements (PPRE) are cis-acting regulatory elements that confer responsiveness to peroxisome proliferators and various fatty acids by serving as target sites for ligand-activated peroxisome proliferator-activated receptor (PPAR)/retinoid X receptor (RXR) heterodimers. Other cellular factors, including additional nuclear hormone receptors, also interact with PPREs and modulate PPAR function. We have developed a positive selection strategy in yeast to identify mammalian factors that functionally interact with PPREs. Saccharomyces cerevisiae containing an integrated copy of the HIS3 gene under transcriptional control of a minimal CYC1 promoter and two copies of the rat enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase PPRE was constructed and transformed with a rat liver cDNA yeast expression library. Plasmids were isolated from his + transformants. One plasmid contained a cDNA encoding the complete rat chicken ovalbumin upstream promoter transcription factor II (COUP-TFII), an orphan member of the nuclear hormone receptor superfamily. COUP-TFII potently activated PPRE-linked reporter gene expression in yeast, and COUP-TFII synthesized in yeast or in vitro formed specific protein/DNA complexes with this PPRE. Significantly, COUP-TFII did not activate transcription of PPRE-linked reporter genes in mammalian cells but rather strongly inhibited induction mediated by PPAR/RXR. Our findings demonstrate the utility of using genetic screening in yeast to identify sequence-specific DNA binding transcription factors.

Animals↗
PubMed2002

Biodegradation of formaldehyde and its derivatives in industrial wastewater with methylotrophic yeast Hansenula polymorpha and with the yeast-bioaugmented activated sludge.

Methylotrophic yeast Hansenula polymorpha were shown to cooperate with activated sludge from biological wastewater treatment stations, enhancing substantially its potential to biodegrade formaldehyde in industrial wastewater. After integration with yeast cells the modified sludge retained its original structure and activity whereas its resistance to elevated formaldehyde concentrations was significantly improved. The applicability of the yeast in the utilization of formaldehyde derivatives, as exemplified by urotropine and trioxane, was also investigated. The treatment of urotropine-containing wastewater with methylotrophic yeast was found to be effective at acidic conditions (pH below 5.5). Trioxane was not degraded due to the stability of an ether bond which made themolecule recalcitrant to oxidation via methylotrophic pathway reactions. It is concluded that the yeast species may be applied to treat wastewater containing formaldehyde and some of its derivatives as either monocultures or as an integrated, specialized element of the activated sludge biocenosis.

Biodegradation, Environmental↗
PubMed1994

Clinical comparison of the Baxter MicroScan Yeast Identification Panel and the Vitek Yeast Biochemical Card.

To determine the reliability of the Baxter MicroScan Yeast Identification Panel, processed by the Walkaway-96, and the Vitek Yeast Biochemical Card, 150 clinical yeast isolates (30 Candida albicans, 67 Candida species, not albicans, 26 Torulopsis glabrata, 13 Cryptococcus neoformans, 4 Saccharomyces cerevisiae, 6 Trichosporon beigelii, 3 Rhodotorula species, and 1 Geotrichum species) were tested on both systems. Results were compared with those obtained by the API 20C and the appearance of yeast cells on cornmeal Tween-80 agar. After inoculation of each system, results were available in 4 hours with MicroScan panels, 24-48 hours with Vitek cards, and 72 hours with the API 20C strips. On initial testing, 101 (67%) and 128 (85%) isolates, respectively, were correctly identified by MicroScan and Vitek. After repeat testing, the number of correctly identified isolates increased to 123 (82%) by MicroScan and to 142 (95%) by Vitek. Yeasts most commonly misidentified were Candida tropicalis, T glabrata, and Candida parapsilosis by MicroScan and C tropicalis and T glabrata by Vitek.

Mycology↗
PubMed1997

Evidence for channeling of intermediates in the oxidative pentose phosphate pathway by soybean and pea nodule extracts, yeast extracts, and purified yeast enzymes.

Evidence is presented that intermediates of the oxidative pentose phosphate pathway (OPPP) are channeled from one pathway enzyme to the next. CO2 produced from [1-14C]glucose in the presence of unlabelled pathway intermediates contained much more radioactivity than predicted by a model in which pathway-produced intermediates are in equilibrium with identical molecules in the bulk phase. This was the case whether glucose 6-phosphate (Glc6P), 6-phosphogluconolactone, or 6-phosphogluconate was added. Assumptions involved in calculating the amount of 14CO2 predicted for free mixing of 14C-labelled and unlabelled intermediates are discussed, together with the following results. (a) 14CO2 production by pea nodules in the presence of 3 mM 6-phosphogluconate was higher than in its absence. (b) Apparent channeling of intermediates was much higher for purified yeast enzymes than for yeast extract. (c) 6-Phosphogluconate and 6-phosphogluconolactone were channeled between yeast Glc6P dehydrogenase and 6-phosphogluconate dehydrogenase despite the absence of 6-phosphogluconolactonase in the purified yeast enzyme mixture. (d) When purified yeast hexokinase was physically separated from Glc6P dehydrogenase and 6-phosphogluconate dehydrogenase by a dialysis membrane, there was no apparent channeling. (e) Poly(ethylene glycol), high salt and detergents had little effect on apparent channeling of OPPP intermediates, which is consistent with a stable complex of enzymes. On the other hand, density gradient centrifugation experiments suggested a more transient interaction between the enzymes. Taken together, the results support channeling of OPPP pathway intermediates.

Carbon Radioisotopes↗
PubMed1987

Evaluation of YeastIdent and Uni-Yeast-Tek yeast identification systems.

The accuracy of the new API YeastIdent system and the Flow Laboratories Uni-Yeast-Tek identification kit with an expanded data base was evaluated in comparison to the API 20C yeast identification system by three laboratories. A total of 489 test isolates were used, biased toward yeasts commonly encountered in clinical specimens. Isolates not in a system's data base were not counted in the evaluation of that system. For isolates in their data base, YeastIdent was 55% accurate and Uni-Yeast-Tek was 40% accurate. By the manufacturer's criteria of reliable identification without additional tests, both systems failed to identify many common and uncommon species. The limited number of substrates and difficulties in assessing results obtained with 11 of the API YeastIdent substrates and apparent errors in the expanded Uni-Yeast-Tek data base appeared to be major factors limiting the accuracy of these systems.

Computers↗
PubMed1978

Clinical evaluation of the Uni-Yeast-Tek system for rapid presumptive identification of medically important yeasts.

The results of over 400 tests for identification of clinical yeast isolates as to species using the Uni-Yeast-Tek (UYT) system in comparison with a more conventional system are reported. The conventional system utilized a total of 23 individual tests, including both fermentation and assimilation tests, whereas the UYT system included only 11 separate tests. In the initial phase of the study, coded unknown isolates were evaluated by each of two technologists using both methods independently. After this initial evaluation, the two methods were used in parallel for routine testing of yeast isolates as they were obtained from clinical specimens. A further evaluation of the UYT system was carried out by retrospectively analyzing the species reported from a clinical mycology laboratory during two separate time periods in which different approaches to yeast identification were employed. A total of 92% of the isolates tested with the UYT system were correctly reported within 72 h, 96% were correctly named after 1 week of incubation, and 97% were correctly reported after 2 weeks of incubation of UYT plates at 30 degrees C when results of the two phases of the study were analyzed together. With the conventional system, 88% of the isolates were correctly reported at 72 h, 96% at 1 week, and 98% after 2 weeks of incubation of biochemical tests. Retrospective analysis of laboratory records revealed no major changes in species reported after adoption of the UYT system for routine testing of clinical isolates. The data presented in this report suggest that the UYT system can be expected to yield rapid presumptive identification of clinical yeast isolates with reasonable confidence when certain minor limitations that are discussed in the text are taken into account.

Evaluation Studies as Topic↗
PubMed2003

Making yeast tremble: yeast models as tools to study neurodegenerative disorders.

Genetic experiments in mice, which are indispensable for studying the molecular basis of neurological disorders, have certain limitations that include slow pace and high costs. It is therefore not surprising that in recent years numerous neurological diseases have been modeled in genetically tractable organisms, including Drosophila, Caenorhabditis elegans, and yeast. Yeast models in particular have a special advantage with respect to genome-wide experimental approaches as a result of the completed sequencing of the genome, the availability of a collection of precise deletion mutants of every gene in the genome, and the rapidly evolving databases of yeast protein-protein interactions and gene expression patterns. These large and easily accessible bodies of information, coupled with the ease with which yeast can be manipulated genetically, have led to dissection of novel mechanisms of neurodegenerative disorders. In this review, we discuss how studies in yeast models have already resulted in significant insights into the understanding of neurodegenerative disorders that include prion disease, Parkinson's disease, polyglutamine expansion disorders, Friedreich's ataxia, and Batten disease.

Apoptosis↗
PubMed1988

Pasteur yeasts system, a test-kit for yeasts identification. Its evaluation in comparison with three commercial methods and conventional procedures.

The Pasteur Yeasts System is a commercial prepared kit and scheme for the rapid (48 h) identification of 23 yeasts belonging to 7 genera. The method consists of two parts: a gallery of media to evaluate germ tube production, urease activity, tetrazolium reduction, cycloheximide sensibility and fermentation of three carbohydrates, and an auxanographic method to determine the assimilation pattern of 16 carbohydrates. This system was tested in comparison with API 20 C Auxanogram, Mycotube, Candida Check and conventional procedures to identify 40 yeast strains. Pasteur Yeasts System provided correct identifications for 97.5% of the organisms and proved to have a high reproducibility, accuracy and reliability. The method is useful and facilitates the identification of pathogenic yeasts from clinical specimens in the routine laboratory.

Evaluation Studies as Topic↗
PubMed1983

Pure yeast RNA polymerase B (II) initiates transcription at specific points on supercoiled yeast DNA.

Pure yeast RNA polmymerase B (II) can selectively initiate abortive transcription on a supercoiled recombinant plasmid DNA carrying yeast DNA in the presence of low concentrations of ribonucleoside triphosphates and Mn2+. Five major products ranging between 60 and 150 nucleotides were characterized by hybridization. Three of them originate from the vector pBR322 and two from the yeast DNA insert. Based on a RNA primer extension reaction with recombinant M13 DNAs as template, a method allowing the mapping of the short abortive RNA products has been developed. An initiation site within the yeast DNA insert has thus precisely been mapped. The DNA sequence in this region was determined and showed several relevant features. The in vitro initiation site is preceded by a potential TATATATA box at -40 base pairs and at -105 by the sequence GTTAATCT similar to the consensus sequence GCTCAATCT usually found around 80 base pairs upstream from the cap site. Large blocks of alternated purine pyrimidine residues are found in this region as for several known yeast promotors. The 5' end of the RNA initiated from this site contains several potential signals for the initiation of translation. The possibility that a B to Z transition of DNA could be important for the interaction of the RNA polymerase with its template is discussed.

Base Sequence↗
PubMed1983

Yeast carbamyl phosphate synthetase. Structure of the yeast gene and homology to Escherichia coli carbamyl phosphate synthetase.

A cloned fragment of yeast chromosomal DNA carrying the gene CPA2 coding for the large subunit of arginine-specific carbamyl phosphate synthetase has been sequenced. The cloned DNA has a 3,354-nucleotide long continuous reading frame coding for a polypeptide of 1,117 amino acids. The calculated molecular weight of the encoded polypeptide is 123,787, in good agreement with the reported molecular weight of the yeast carbamyl phosphate synthetase large subunit. The amino acid sequence of yeast carbamyl phosphate synthetase is homologous to the recently determined sequence of Escherichia coli carbamyl phosphate synthetase (Nyunoya, H., and Lusty, C. J. (1983) Proc. Natl. Acad. Sci. U. S. A. 80, 4629-4633) over almost the entire length of the protein. Like the E. coli large subunit, the yeast enzyme exhibits an extensive internal homology between its NH2- and carboxyl-terminal halves. The internal homology in both the yeast and E. coli proteins indicates that the gene coding for the large subunit of carbamyl phosphate synthetase was derived from a tandem duplication which occurred prior to the divergence of eukaryotes and prokaryotes.

Amino Acid Sequence↗
PubMed1991

Transfer of yeast artificial chromosomes from yeast to mammalian cells.

Human DNA can be cloned as yeast artificial chromosomes (YACs), each of which contains several hundred kilobases of human DNA. This DNA can be manipulated in the yeast host using homologous recombination and yeast selectable markers. In relatively few steps it is possible to make virtually any change in the cloned human DNA from single base pair changes to deletions and insertions. In order to study the function of the cloned DNA and the effects of the changes made in the yeast, the human DNA must be transferred back into mammalian cells. Recent experiments indicate that large genes can be transferred from the yeast host to mammalian cells in tissue culture and that the genes are transferred intact and are expressed. Using the same methods it may soon be possible to transfer YAC DNA into the mouse germ line so that the expression and function of genes cloned in YACs can be studied in developing and adult mammalian animals.

Animals↗
PubMed1991

Cloning of a yeast U1 snRNP 70K protein homologue: functional conservation of an RNA-binding domain between humans and yeast.

We have cloned and sequenced a gene encoding a yeast homologue of the U1 snRNP 70K protein. The gene, SNP1, encodes a protein which has 30% amino acid identity with the human 70K protein and has a predicted molecular weight of 34 kDa. The yeast and human sequences are more closely related to each other than to other (non-U1) RNA-binding proteins, but diverge considerably in their C-terminal portions. In particular, SNP1 lacks the charged carboxy terminus of the human 70K protein. A yeast strain, a alpha 115, was constructed in which one allele of the SNP1 gene contained a 554 bp deletion. Tetrad analysis of a alpha 115 showed that the SNP1 gene is essential for the viability of yeast cells. The complete human 70K gene did not complement snp1, but the lethal snp1 mutation was rescued by plasmids bearing a chimera in which over half the yeast gene was replaced with the homologous region of the human 70K gene, including the RNA-binding domain. These results suggest that SNP1 encodes a functional homologue of the U1 snRNP 70K protein.

Amino Acid Sequence↗
PubMed1977

Enzymes of the yeast lytic system produced by Arthrobacter GJM-1 bacterium and their role in the lysis of yeast cell walls.

Yeast lytic system produced by Arthrobacter GJM-1 bacterium during growth on baker's yeast cell walls contains a complete set of enzymes which can hydrolyze all structural components of cell walls of Saccharomyces cerevisiae. Chromatographic fractionation of the lytic system showed the presence of two types of endo-beta-1,3-glucanase. Rapid lysis of isolated cell walls of yeast was induced only by endo-beta-1,3-glucanase exhibiting high affinity to insoluble beta-1,3-glucans and releasing laminaripentaose as the main product of hydrolysis of beta-1,3-glucans. This enzyme was able to lyse intact cells of S. cerevisiae only in the presence of an additional factor present in the Arthrobacter GJM-1 lytic system, which was identified as an alkaline protease. This enzyme possesses the lowest molecular weight among other identified enzyme components present in the lytic system. Its role in the solubilization of yeast cell walls from the outer surface by endo-beta-1,3-glucanase could be substituted by preincubation of cells with Pronase or by allowing the glucanase to act on cells in the presence of thiol reagents. The mechanism of lysis of intact cells and isolated cell walls by the enzymes of Arthrobacter GJM-1 is discussed in the light of the present conception of yeast cell wall structure.

Arthrobacter↗
PubMed2006

How to get the most from fission yeast genome data: a report from the 2006 European Fission Yeast Meeting computing workshop.

A fission yeast computing workshop 'How to get the most from the fission yeast genome data' was run as a satellite to the European Fission Yeast Meeting. The broad aims of the workshop were to provide fission yeast bench biologists with a set of tools and protocols to query the fission yeast genome data in specific ways, in order to extract biologically meaningful information of interest, which can be tailored to the needs of individual research projects. A description of the workshop content is provided and a selection of the tools presented are reviewed.

Computational Biology↗
PubMed1989

Pores from mitochondrial outer membranes of yeast and a porin-deficient yeast mutant: a comparison.

Reconstitution experiments were performed on lipid bilayer membranes in the presence of purified mitochondrial porin from yeast and of detergent-solubilized mitochondrial outer membranes of a porin-free yeast mutant. The addition of the porin resulted in a strong increase of the membrane conductance, which was caused by the formation of ion-permeable channels in the membranes. Yeast porin has a single-channel conductance of 4.2 nS in 1 M KCl. In the open state it behaves as a general diffusion pore with an effective diameter of 1.7 nm and possesses properties similar to other mitochondrial porins. Surprisingly, the membrane conductance also increased in the presence of detergent extracts of the mitochondrial outer membrane of the mutant. Single-channel recordings of lipid bilayer membranes in the presence of small concentration of the mutant membranes suggested that this membrane also contained a pore. The reconstituted pores had a single-channel conductance of 2.0 nS in 1 M KCl and the characteristics of general diffusion pores with an estimated effective diameter of 1.2 nm. This means that the pores present in the mitochondrial outer membranes of the yeast mutant have a much smaller effective diameter than "normal" mitochondrial porins. Zero-current membrane potential measurements suggested that the second mitochondrial porin is slightly cation-selective, while yeast porin is slightly anion-selective in the open state but highly cation-selective in the closed state. The possible role of these pores in the metabolism of mitochondria is discussed.

Electric Conductivity↗