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PubMed1982

Infections of Paramecium bursaria with bacteria and yeasts.

Infections of Paramecium bursaria with bacteria and yeasts are reported. Bacteria and yeasts multiply in the algae-free ciliate and are transmitted at various conditions as are symbiotic chlorellae. Like chlorellae, the bacteria and the yeast cells are situated in perisymbiont vacuoles. Both bacteria and yeasts maintain their capability for independent existence and can be grown on standard nutrient agar. Infection experiments show that aposymbiotic P. bursaria can be infected with Chlorella, bacteria and yeast. Chlorella-bearing P. bursaria cannot be infected with bacteria or yeast. Bacteria-bearing paramecia can be infected with Chlorella but not with yeast. Yeast-bearing paramecia can be infected with Chlorella but not with bacteria. Following infections with Chlorella the paramecia lose their bacteria or yeast symbionts. The bacteria found in P. bursaria probably belong to the genus Pseudomonas; the yeast has been identified as Rodutorula rubra.

Animals↗
PubMed1992

Influence of yeast culture on feeder calves and lambs.

Four experiments were conducted to determine the influence of yeast culture on 1) the health and performance of feeder calves, 2) the response of calves to an infectious bovine rhinotracheitis virus (IBRV) infection, and 3) nutrient utilization in lambs fasted for 3 d. In Exp. 1, 108 feeder calves were transported from Tennessee to Texas (1,600 km) and fed receiving diets containing 0 or .75% yeast culture and .35 or .69% P in a 2 x 2 factorial arrangement of treatments. In Exp. 2, 101 calves were transported 950 kg from Austin, TX to Bushland, TX and fed receiving diets containing 0, .75, 1.125, or 1.5% yeast culture. Yeast culture did not significantly affect the health or performance of calves in either experiment, although morbid calves fed yeast culture required fewer (P less than .05) days of antibiotic therapy in Exp. 2. In Exp. 3, feeder steers were fed diets containing 0 or .75% yeast culture and challenged intranasally with IBRV. Calves fed yeast culture tended to maintain heavier weights and higher DMI during IBRV infection than did steers fed the control diet. In Exp. 4, feeder lambs were fasted for 3 d and refed diets containing 0, .75, 1.125, or 1.5% yeast culture during a N and mineral balance trial. Lambs fed yeast culture had greater (P less than .08) N balance and tended to have greater Zn and Fe balance than control lambs. Results of these studies are interpreted to suggest that supplementation of morbid calves with yeast culture can have beneficial effects (fewer sick days, higher feed intakes) and that these effects may be mediated by improved N, Zn, and Fe metabolism.

Alkaline Phosphatase↗
PubMed1992

The effect of dietary yeast on the activity of stable chronic Crohn's disease.

The effect of dietary yeast on the activity of stable Crohn's disease was assessed in 19 patients. During the 1st month patients continued their usual diet (base-line period), but during the next 2 months dietary yeast was excluded except that during 1 month patients took baker's yeast capsules while for the other month they took placebo capsules. The patients' mean Pettit Crohn's disease activity index (CDAI) while taking baker's yeast (mean, 107.9; SE, 6.1) was significantly greater than during yeast exclusion (mean, 102.1; SE, 5.7; p less than 0.05). The mean of each patient's maximum CDAI during yeast exclusion (mean, 107.1; SE, 5.7) was significantly lower than those during the base-line (mean, 115.2; SE, 6.1; p less than 0.05) and baker's yeast inclusion periods (mean, 113.9; SE, 6.7; p less than 0.05). Patients with elevated yeast antibodies tended to develop a higher CDAI while receiving baker's yeast (13 of 15). These results suggest that dietary yeast may affect the activity of Crohn's disease.

Adult↗
PubMed2002

Enumeration and identification of yeasts associated with commercial poultry processing and spoilage of refrigerated broiler carcasses.

Yeasts associated with broiler carcasses taken from various stages of commercial poultry processing operations and broiler carcasses stored at refrigerated temperatures were enumerated and identified. Whole carcass rinses were performed to recover yeasts from carcasses taken from a processing facility and processed carcasses stored at 4 degrees C for up to 14 days. Yeasts in the carcass rinsates were enumerated on acidified potato dextrose agar and identified with the MIDI Sherlock Microbial Identification System. Dendrograms of fatty acid profiles of yeast were prepared to determine the degree of relatedness of the yeast isolates. Findings indicated that as the carcasses are moved through the processing line, significant decreases in the number of yeasts associated with broiler carcasses usually occur, and the composition of the yeast flora of the carcasses is altered. Significant (P < 0.05) increases in the yeast population of the carcasses generally occur during storage at 4 degrees C, however. Furthermore, it was determined that the same strain of yeast may be recovered from different carcasses at different points in the processing line and that the same strain of yeast may be isolated from carcasses processed on different days in the same processing facility.

Animals↗
PubMed2001

A comparison of methods for yeast identification including CHROMagar Candida, Vitek system YBC and a traditional biochemical method.

BACKGROUND: CHROMagar Candida (CAC) is a new chromogenic medium for the presumptive identification of clinically-important yeast isolates. A yeast biochemical card (YBC), a part of the Vitek system is an automatic method for the identification of clinically-important yeast isolates. We conducted a comparison of these two methods with a traditional biochemical method in order to choose a rapid and accurate technique for yeast identification. METHODS: All yeast isolates were inoculated onto Sabourand dextrose agar (SDA) and CAC, and incubated at 30 degrees C for 48 hours. All isolates were simultaneously tested using traditional biochemical methods and the yeast biochemical card from the Vitek system. RESULTS: We evaluated 235 yeast isolates from clinical specimens, including 89 Candida albicans, 47 Candida tropicalis, 43 Candida glabrata, six Trichosporon beigelii, and five Candida krusei in addition to 45 isolates of other yeast species. Isolates were presumptively identified on the basis of colony color and appearance on CAC medium. These observations were compared with a traditional biochemical yeast-identification method and also with YBC from the Vitek system. For five commonly-isolated species (Candida albicans, Candida tropicalis, Candida glabrata, Candida krusei and Trichosporon beigelii), agreement among the CAC medium, YBC method and traditional biochemical method were 98.9% (187/189), 96.3% (182/189), 100% (189/189), respectively. CONCLUSIONS: From our comparison, the CAC medium is a convenient and economic method to identify five commonly-noted yeast species, and the YBC method warrants a greater cost and requires a longer period of time to obtain reliable results.

Candida↗
PubMed2004

[Construction and expression of DNA-binding domain plasmid with hepatitis B virus e antigen in yeast double hybrid system].

BACKGROUND: Using hepatitis B virus e antigen (HBeAg) gene to construct the DNA-binding domain vector, which can express HBeAg in yeast cell, and can be used in yeast double hybrid as "bait plasmid" to look for the gene from the cDNA library, which expresses the protein that can interact with HBeAg. METHODS: PCR was performed to amplify the HBeAg gene from a sera of hepatitis B patient. The product of the amplification was inserted into T-vector and was verified by sequencing. Then it was inserted into the "bait" plasmid pGBKT7 after the digestion with the restricted endonuclease of EcoR I and Sal I. The plasmid was transformed into the yeast cell. PCR was used to verify whether the plasmid was transformed into yeast. The HBeAg protein expressed in the cell was confirmed by Western blot. Using nutrition selection assay to verify the constructed plasmid alone could not activate the reporter gene in the yeast cell. RESULTS: Sequenced and digested by two endonucleases, the recombined vectors pGBKT7-eAg produced anticipated fragment. PCR verified that there was HBeAg fragment in the yeast. Having assayed by Western blotting, it was shown that the yeast cell transformed with pGBKT7-eAg vector had positive signal which could not be seen in the control. Tested by the nutrition selection assay, the recombined vectors pGBKT7-eAg could not activate LacZ reporter gene in the yeast. CONCLUSION: DNA-binding domain plasmid was successfully constructed and could express HBeAg proteins in the yeast cell but could not activate transcription of LacZ reporter gene alone. The recombined plasmid can be used in yeast double hybrid.

Genetic Vectors↗
PubMed2000

Antimicrobial and biological effects of ipemphos and amphos on bacterial and yeast strains.

In this study, the antimicrobial effects of monophosphazenes such as SM ipemphos and amphos were examined on bacterial and yeast strains. In addition, the biological effects of these compounds were tested on the lipid level of Saccharomyces cerevisiae and Candida albicans cells. The SM has an antimicrobial effect on the bacterial and yeast strains within the range of 100 and 1500 microg. When the concentration was increased, the inhibition zone expanded on the growth media ( p < 0.01; p < 0.001). The ipemphos did not affect the bacterial and yeast cells in the 100 and 600 microg range. In addition, the amphos did not show an antimicrobial effect on the bacterial cells between 100 and 300 microg or on yeast cells at any of the administered concentrations. In vitro media, the biological effects of these molecules were compared with vitamin E, melatonin and fish oil on the yeast cells. We have found that monophosphazenes have growth effects on the cells in vitro media. The lipid level of S. cerevisiae cells was decreased by 300 microg doses of vitamin E, fish oil, and ipemphos (respectively; p < 0.05, p < 0.01, and p < 0. 001). In addition, the lipid levels of the same yeast cells were depressed by 1000-microg doses in all supplemented groups. However, it was observed that the highest decrease in lipid level of S. cerevisiae cells occurred in the amphos group ( p < 0.001). The lipid levels of the C. albicans cells were significantly reduced ( p < 0.01) by 300 microg of amphos and melatonin. In contrast, the vitamin E and fish oil significantly raised ( p < 0.01; p < 0.001) the lipid level of the same yeast cell, as compared with the control. In addition, the lipid level of these cells was increased by administration of 1000 microg vitamin E, and melatonin ( p < 0.01). In conclusion, while high concentrations of ipemphos and amphos have an antimicrobial effect on bacterial and yeast cells, amphos did not affect the yeast cells. While ipemphos and amphos increased cell growth in media, they reduced the lipid level of C. albicans and S. cerevisiae. In addition, the antioxidants such as vitamin E, melatonin, and fish oils affected the lipid level of yeast cells.

Anti-Bacterial Agents↗
PubMed2000

Tailoring wine yeast for the new millennium: novel approaches to the ancient art of winemaking.

Yeasts are predominant in the ancient and complex process of winemaking. In spontaneous fermentations, there is a progressive growth pattern of indigenous yeasts, with the final stages invariably being dominated by the alcohol-tolerant strains of Saccharomyces cerevisiae. This species is universally known as the 'wine yeast' and is widely preferred for initiating wine fermentations. The primary role of wine yeast is to catalyze the rapid, complete and efficient conversion of grape sugars to ethanol, carbon dioxide and other minor, but important, metabolites without the development of off-flavours. However, due to the demanding nature of modern winemaking practices and sophisticated wine markets, there is an ever-growing quest for specialized wine yeast strains possessing a wide range of optimized, improved or novel oenological properties. This review highlights the wealth of untapped indigenous yeasts with oenological potential, the complexity of wine yeasts' genetic features and the genetic techniques often used in strain development. The current status of genetically improved wine yeasts and potential targets for further strain development are outlined. In light of the limited knowledge of industrial wine yeasts' complex genomes and the daunting challenges to comply with strict statutory regulations and consumer demands regarding the future use of genetically modified strains, this review cautions against unrealistic expectations over the short term. However, the staggering potential advantages of improved wine yeasts to both the winemaker and consumer in the third millennium are pointed out.

Consumer Behavior↗
PubMed1982

Cloning yeast telomeres on linear plasmid vectors.

We have constructed a linear yeast plasmid by joining fragments from the termini of Tetrahymena ribosomal DNA to a yeast vector. Structural features of the terminus region of the Tetrahymena rDNA plasmid maintained in the yeast linear plasmid include a set of specifically placed single-strand interruptions within the cluster of hexanucleotide (C4A2) repeat units. An artificially constructed hairpin terminus was unable to stabilize a linear plasmid in yeast. The fact that yeast can recognize and use DNA ends from the distantly related organism Tetrahymena suggests that the structural features required for telomere replication and resolution have been highly conserved in evolution. The linear plasmid was used as a vector to clone chromosomal telomeres from yeast. One Tetrahymena end was removed by restriction digestion, and yeast fragments that could function as an end on a linear plasmid were selected. Restriction mapping and hybridization analysis demonstrated that these fragments were yeast telomeres, and suggested that all yeast chromosomes might have a common telomere sequence. Yeast telomeres appear to be similar in structure to the rDNA of Tetrahymena, in which specific nicks or gaps are present within a simple repeated sequence near the terminus of the DNA.

Animals↗
PubMed1986

Yeast shuttle and integrative vectors with multiple cloning sites suitable for construction of lacZ fusions.

We report yeast/Escherichia coli shuttle vectors suitable for fusing yeast promoter and coding sequences to the lacZ gene of E. coli. The vectors contain a region of multiple unique restriction sites including EcoRI, KpnI, SmaI, BamHI, XbaI, SalI, PstI, SphI and HindIII. The region with the unique cloning sites has been introduced in both orientations with respect to lacZ and occurs proximal to the eighth codon of the gene. All the restriction sites have been phased to three different reading frames. Two series of vectors have been constructed. The first series (YEp) has two origins of replication (ori), i.e., of the yeast 2 mu circle and of the ColE1 plasmid of E. coli, and can therefore replicate autonomously in both organisms. These shuttle vectors also have the ApR gene of E. coli and either the yeast LEU2 or URA3 genes to allow for selection of both E. coli and yeast transformants. The second series of vectors (YIp) are identical in all respects to the YEp vectors except that they lack the 2 mu ori. The YIp vectors can be used to integrate lacZ fusions into yeast chromosomal DNA. None of the vectors express beta-galactosidase (beta Gal) in yeast or E. coli in the absence of inserted yeast promoter sequences. The 5'-nontranslated sequences and parts of the coding sequences of various yeast genes have been cloned into representative lacZ fusion vectors. In-frame gene fusions can be detected by beta Gal activity when either yeast or E. coli clones are plated on media containing XGal indicator. Quantitative determinations of promoter activity were made by colorimetric assay of beta Gal activity in whole cells. Fusion of the yeast CYC1 gene to lacZ in one of the vectors allowed detection of regulated expression of this gene when cells were grown under conditions of catabolite repression or derepression.

Cloning, Molecular↗
PubMed2026

Diversification of yeast proteins as an approach for the development of sustainable food systems.

Despite growing trend in sustainable protein sources, yeast proteins have mainly been explored as a source of bioactive peptides using a monospecies and general protein approach. The contribution of highly abundant protein fractions in the yeast proteome to peptide formation remains insufficiently investigated, limiting a comprehensive understanding of yeast proteins as optimized peptide sources. The current review presents a systematic analysis of yeast proteins as emerging protein sources and evaluates the suitability of high-abundance proteins as bioactive peptide precursors by in silico techniques. Moreover, brewery by-product and single-cell yeast protein approaches are compared in terms of composition and techno-functionality whereas peptide formation mechanisms (in situ and ex situ) and regulatory aspects for food applications are also addressed. Cytoplasmic metabolic proteins, particularly glycolytic enzymes (GAPDH), are identified as highly abundant fractions of the yeast proteome. Proteins associated with cell and organelle membranes also contribute substantially based on cellular localization. These findings imply that such proteins may act as key precursors of yeast-derived bioactive peptides. In silico hydrolysis with Alcalase suggests a tendency toward the generation of short-chain peptides (3-11/14 aa), which may support biological activity. Moreover, peptide profiles appear to vary across yeast species, highlighting the role of species diversity in peptide generation. While single-cell yeast protein allows more controlled production than brewery by-products, nucleic acid content in both may limit applications. Overall, yeast proteins appear to be metabolically adaptable and species-diverse sources for various biological peptides.

Saccharomyces cerevisiae↗
PubMed2006

Hydrothermal decomposition of yeast cells for production of proteins and amino acids.

This study examines hydrothermal decomposition of Baker's yeast cells, used as a model for spent Brewer's yeast waste, into protein and amino acids. The reaction was carried out in a closed batch reactor at various temperatures between 100 and 250 degrees C. The reaction products were separated into water-soluble and solid residue. The results demonstrated that the amount of yeast residue decreased with increasing hydrolysis temperature. After 20 min reaction in water at 250 degrees C, 78% of yeast was decomposed. The highest amount of protein produced was also obtained at this condition and was found to be 0.16 mg/mg dry yeast. The highest amount of amino acids (0.063 mg/mg dry yeast) was found at the lowest temperature tested after 15 min. The hydrolysis product obtained at 200 degrees C was tested as a nutrient source for yeast growth. The growth of yeast cells in the culture medium containing 2 w/v% of this product was comparable to that of the cells grown in the medium containing commercial yeast extract at the same concentration. These results demonstrated the feasibility of using subcritical water to potentially decompose proteinaceous waste such as spent Brewer's yeast while recovering more useful products.

Amino Acids↗
PubMed1999

Highly divergent amino termini of the homologous human ALR and yeast scERV1 gene products define species specific differences in cellular localization.

The yeast scERV1 gene product is involved in the biogenesis of mitochondria and is indispensable for viability and regulation of the cell cycle. Recently the general importance of this gene for the eukaryotic cell was shown by the identification of a structural and functional human homologue. The homologous mammalian ALR (Augmenter of Liver Regeneration) genes from man, mouse and rat are involved in the phenomenon of liver regeneration. A low expression rate of the genes is found in all investigated cells and mammalian tissues but it is specifically induced after damage of liver organs and is especially high during spermatogenesis. The alignment of the different proteins identifies a highly conserved carboxy terminus with more than 40% identical amino acids between yeast and mammals. The conserved carboxy terminus is functionally interchangeable between distantly related species like yeast and man. In contrast, the amino terminal parts of the proteins display a high degree of variability and significant differences even among closely related species. This finding leads to the problem whether the amino termini have comparable or divergent functions in different species. In this study we demonstrate by heterologous complementation experiments in yeast that the complete human ALR protein with its own amino terminus is not able to substitute for the yeast scERV1 protein. Fusion proteins of Alrp and scErv1p with the green fluorescence protein were created to investigate the respective subcellular localizations of these homologous proteins in yeast and human cells. In yeast cells human Alrp accumulates in the cytoplasm in contrast to yeast scErv1p that is preferentially associated with yeast mitochondria. Comparable studies with human cells clearly show that the homologous human Alrp is located in the cytosol of these cells. Fractionation experiments and antibody tests with yeast and human mitochondria and cellular extracts verify these findings.

Amino Acid Sequence↗
PubMed1999

Multisite-specific tRNA:m5C-methyltransferase (Trm4) in yeast Saccharomyces cerevisiae: identification of the gene and substrate specificity of the enzyme.

Several genes encoding putative RNA:5-methylcytidine-transferases (m5C-transferases) from different organisms, including yeast, have been identified by sequence homology with the recently identified 16S rRNA:m5C967-methyltransferase (gene SUN) from Escherichia coli. One of the yeast ORFs (YBL024w) was amplified by PCR, inserted in the expression vector pET28b, and the corresponding protein was hyperexpressed in E. coli BL21 (DE3). The resulting N-terminally His6-tagged recombinant Ybl024p was purified to apparent homogeneity by one-step affinity chromatography on Ni2+-NTA-agarose column. The activity and substrate specificity of the purified Ybl024p were tested in vitro using T7 transcripts of different yeast tRNAs as substrates and S-adenosyl-L-methionine as a donor of the methyl groups. The results indicate that yeast ORF YBL024w encodes S-adenosyl-L-methionine-dependent tRNA: m5C-methyltransferase that is capable of methylating cytosine to m5C at several positions in different yeast tRNAs and pre-tRNAs containing intron. Modification of tRNA occurs at all four positions (34, 40, 48, and 49) at which m5C has been found in yeast tRNAs sequenced so far. Disruption of the ORF YBL024w leads to the complete absence of m5C in total yeast tRNA. Moreover no tRNA:m5C-methyltransferase activity towards all potential m5C methylation sites was detected in the extract of the disrupted yeast strain. These results demonstrate that the protein product of a single gene is responsible for complete m5C methylation of yeast tRNA. Because this newly characterized multisite-specific modification enzyme Ybl024p is the fourth tRNA-specific methyltransferase identified in yeast, we suggest designating it as TRM4, the gene corresponding to ORF YBL024w.

Amino Acid Sequence↗
PubMed1977

Initial position of aminoacylation of individual Escherichia coli, yeast, and calf liver transfer RNAs.

Transfer RNAs from Escherichia coli, yeast (Sacharomyces cerevisiae), and calf liver were subjected to controlled hydrolysis with venom exonuclease to remove 3'-terminal nucleotides, and then reconstructed successively with cytosine triphosphate (CTP) and 2'- or 3'-deoxyadenosine 5'-triphosphate in the presence of yeast CTP(ATP):tRNA nucleotidyltransferase. The modified tRNAs were purified by chromatography on DBAE-cellulose or acetylated DBAE-cellulose and then utilized in tRNA aminoacylation experiments in the presence of the homologous aminoacyl-tRNA synthetase activities. The E. coli, yeast, and calf liver aminoacyl-tRNA synthetases specific for alanine, glycine, histidine, lysine, serine, and threonine, as well as the E. coli and yeast prolyl-tRNA synthetases and the yeast glutaminyl-tRNA synthetase utilized only those homologous modified tRNAs terminating in 2'-deoxyadenosine (i.e., having an available 3'-OH group). This is interpreted as evidence that these aminoacyl-tRNA synthetases normally aminoacylate their unmodified cognate tRNAs on the 3'-OH group. The aminoacyl-tRNA synthetases from all three sources specific argining, isoleucine, leucine, phenylalanine, and valine, as well as the E. coli and yeast enzymes specific for methionine and the E. coli glutamyl-tRNA synthetase, used as substrates exclusively those tRNAs terminating in 3'-deoxyadenosine. Certain aminoacyl-tRNA synthetases, including the E. coli, yeast, and calf liver asparagine and tyrosine activating enzymes, the E. coli and yeast cysteinyl-tRNA synthetases, and the aspartyl-tRNA synthetase from yeast, utilized both isomeric tRNAs as substrates, although generally not at the same rate. While the calf liver aspartyl- and cysteinyl-tRNA synthetases utilized only the corresponding modified tRNA species terminating in 2'-deoxyadenosine, the use of a more concentrated enzyme preparation might well result in aminoacylation of the isomeric species. The one tRNA for which positional specificity does seem to have changed during evolution is tryptophan, whose E. coli aminoacyl-tRNA synthetase utilized predominantly the cognate tRNA terminating in 3'-deoxyadenosine, while the corresponding yeast and calf liver enzymes were found to utilize predominantly the isomeric tRNAs terminating in 2'-deoxyadenosine. The data presented indicate that while there is considerable diversity in the initial position of aminoacylation of individual tRNA isoacceptors derived from a single source, positional specificity has generally been conserved during the evolution from a prokaryotic to mammalian organism.

Amino Acids↗
PubMedDate not supplied

Rolling adhesion kinematics of yeast engineered to express selectins.

Selectins are cell adhesion molecules that mediate capture of leukocytes on vascular endothelium as an essential component of the inflammatory response. Here we describe a method for yeast surface display of selectins, together with a functional assay that measures rolling adhesion of selectin-expressing yeast on a ligand-coated surface. E-selectin-expressing yeast roll specifically on surfaces bearing sialyl-Lewis-x ligands. Observation of yeast rolling dynamics at various stages of their life cycle indicates that the kinematics of yeast motion depends on the ratio of the bud radius to the parent radius (B/P). Large-budded yeast "walk" across the surface, alternately pivoting about bud and parent. Small-budded yeast "wobble" across the surface, with bud pivoting about parent. Tracking the bud location of budding yeast allows measurement of the angular velocity of the yeast particle. Comparison of translational and angular velocities of budding yeast demonstrates that selectin-expressing cells are rolling rather than slipping across ligand-coated surfaces.

Biomechanical Phenomena↗
PubMed2006

Rhodamine-pink as a genetic marker for yeast populations in wine fermentation.

Winemaking with selected yeasts requires simple techniques to monitor the inoculated yeast. New high-concentration rhodamine-resistant mutants and low-concentration rhodamine-pink mutants, easy to detect by replica-plate assay, were obtained from selected wine yeasts. The rhodamine-pink mutations were dominant and were located at the pdr5 locus that encodes for the Pdr5 ATP-binding cassette multidrug resistance transporter. The mutants were genetically stable but had lost the killer phenotype of the parent yeast strain. They were genetically improved by elimination of recessive growth-retarding alleles followed by crossing with selected killer wine yeasts. Several spore-clones were selected according to their must fermentation kinetics and the organoleptic quality of the wine. Some spore-clones were tested in industrial winemaking, and they were easily monitored during must fermentation using a simple color-plate assay. They accounted for >96% of the total yeasts in the must, and the resulting wine had as good a quality as those made with standard commercial wine yeasts. The rhodamine-pink yeasts may also be detected by direct seeding onto rhodamine agar or by observation under fluorescence microscopy. These possibilities greatly reduce the time of analysis and make the monitoring procedure for rhodamine-pink yeasts faster, easier, and cheaper than for the genetically marked wine yeasts obtained previously.

ATP-Binding Cassette Transporters↗
PubMed2001

Structural and functional similarities between the central eukaryotic initiation factor (eIF)4A-binding domain of mammalian eIF4G and the eIF4A-binding domain of yeast eIF4G.

The translation eukaryotic initiation factor (eIF)4G of the yeast Saccharomyces cerevisiae interacts with the RNA helicase eIF4A (a member of the DEAD-box protein family; where DEAD corresponds to Asp-Glu-Ala-Asp) through a C-terminal domain in eIF4G (amino acids 542-883). Mammalian eIF4G has two interaction domains for eIF4A, a central domain and a domain close to the C-terminus. This raises the question of whether eIF4A binding to eIF4G is conserved between yeast and mammalian cells or whether it is different. We isolated eIF4G1 mutants defective in eIF4A binding and showed that these mutants are strongly impaired in translation and growth. Extracts from mutants displaying a temperature-sensitive phenotype for growth have low in vitro translation activity, which can be restored by addition of the purified eIF4G1-eIF4E complex, but not by eIF4E alone. Analysis of mutant eIF4G(542-883) proteins defective in eIF4A binding shows that the interaction of yeast eIF4A with eIF4G1 depends on amino acid motifs that are conserved between the yeast eIF4A-binding site and the central eIF4A-binding domain of mammalian eIF4G. We show that mammalian eIF4A binds tightly to yeast eIF4G1 and, furthermore, that mutant yeast eIF4G(542-883) proteins, which do not bind yeast eIF4A, do not interact with mammalian eIF4A. Despite the conservation of the eIF4A-binding site in eIF4G and the strong sequence conservation between yeast and mammalian eIF4A (66% identity; 82% similarity at the amino acid level) mammalian eIF4A does not substitute for the yeast factor in vivo and is not functional in a yeast in vitro translation system.

Amino Acid Sequence↗