scholarly journals Role of Nitrogen and Carbon Transport, Regulation, and Metabolism Genes for Saccharomyces cerevisiae Survival In Vivo

2006 ◽  
Vol 5 (5) ◽  
pp. 816-824 ◽  
Author(s):  
Joanne M. Kingsbury ◽  
Alan L. Goldstein ◽  
John H. McCusker
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acids ◽  
Drug Targets ◽  
Carbon Sources ◽  
Nitrogen Sources ◽  
Opportunistic Pathogen ◽  
Close Relative ◽  
Environment Interaction ◽  
Nitrogenous Compounds

ABSTRACT Saccharomyces cerevisiae is both an emerging opportunistic pathogen and a close relative of pathogenic Candida species. To better understand the ecology of fungal infection, we investigated the importance of pathways involved in uptake, metabolism, and biosynthesis of nitrogen and carbon compounds for survival of a clinical S. cerevisiae strain in a murine host. Potential nitrogen sources in vivo include ammonium, urea, and amino acids, while potential carbon sources include glucose, lactate, pyruvate, and fatty acids. Using mutants unable to either transport or utilize these compounds, we demonstrated that no individual nitrogen source was essential, while glucose was the most significant primary carbon source for yeast survival in vivo. Hydrolysis of the storage carbohydrate glycogen made a slight contribution for in vivo survival compared with a substantial requirement for trehalose hydrolysis. The ability to sense and respond to low glucose concentrations was also important for survival. In contrast, there was little or no requirement in vivo in this assay for any of the nitrogen-sensing pathways, nitrogen catabolite repression, the ammonium- or amino acid-sensing pathways, or general control. By using auxotrophic mutants, we found that some nitrogenous compounds (polyamines, methionine, and lysine) can be acquired from the host, while others (threonine, aromatic amino acids, isoleucine, and valine) must be synthesized by the pathogen. Our studies provide insights into the yeast-host environment interaction and identify potential antifungal drug targets.

Development of Saccharomyces cerevisiae as a Model Pathogen: A System for the Genetic Identification of Gene Products Required for Survival in the Mammalian Host Environment

Genetics ◽  
2001 ◽  
Vol 159 (2) ◽  
pp. 499-513
Author(s):  
Alan L Goldstein ◽  
John H McCusker
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Genetic Manipulation ◽  
Glyoxylate Cycle ◽  
Opportunistic Pathogen ◽  
Genetic Identification ◽  
Close Relative ◽  
Mammalian Host ◽  
Gene Products ◽  
Host Environment

Abstract Saccharomyces cerevisiae, a close relative of the pathogenic Candida species, is an emerging opportunistic pathogen. An isogenic series of S. cerevisiae strains, derived from a human clinical isolate, were used to examine the role of evolutionarily conserved pathways in fungal survival in a mouse host. As is the case for the corresponding Candida albicans and Cryptococcus neoformans mutants, S. cerevisiae purine and pyrimidine auxotrophs were severely deficient in survival, consistent with there being evolutionary conservation of survival traits. Resistance to the antifungal drug 5-fluorocytosine was not deleterious and appeared to be slightly advantageous in vivo. Of mutants in three amino acid biosynthetic pathways, only leu2 mutants were severely deficient in vivo. Unlike the glyoxylate cycle, respiration was very important for survival; however, the mitochondrial genome made a respiration-independent contribution to survival. Mutants deficient in pseudohyphal formation were tested in vivo; flo11Δ mutants were phenotypically neutral while flo8Δ, tec1Δ, and flo8Δ tec1Δ mutants were slightly deficient. Because of its ease of genetic manipulation and the immense S. cerevisiae database, which includes the best annotated eukaryotic genome sequence, S. cerevisiae is a superb model system for the identification of gene products important for fungal survival in the mammalian host environment.

THE IN VITRO RELEASE OF AMINO ACIDS BY RUMEN PAPILLAE

1980 ◽  
Vol 60 (2) ◽  
pp. 281-291 ◽  
Author(s):  
R. J. BOILA ◽  
L. P. MILLIGAN
Keyword(s):  
Amino Acids ◽  
Carbon Sources ◽  
In Vitro Release ◽  
Nitrogen Sources ◽  
Chromatographic Technique ◽  
Salts Of Organic Acids ◽  
Liquid Chromatographic ◽  
Vitro Release ◽  
Effective Source

Rumen papillae from cattle were incubated aerobically with combinations of NH4Cl, amino acids and salts of organic acids, the latter including propionate, pyruvate, α-ketoglutarate and glyoxylate. Amino acids in the incubation media were analyzed using a gas-liquid chromatographic technique entailing separation of the isobutyl-N(0)-heptafluorobutyryl esters: glutamine was recovered with glutamate, asparagine with aspartate, and citrulline with ornithine. Rumen papillae incubated with pyruvate or propionate released alanine, but with the latter substrate only glutamate was effective as a nitrogen source. Glycine and glutamate plus glutamine were released in the presence of glyoxylate and α-ketoglutarate, respectively. Serine and aspartate plus asparagine were not quantitatively major products released by rumen papillae. Glutamate was an effective source of nitrogen for the release of alanine and glycine with pyruvate and glyoxylate, respectively, as carbon sources. When rumen papillae were incubated with pyruvate or glyoxylate as the added carbon source, glutamine nitrogen disappeared and was not accounted for by the amino acids measured. With arginine as a substrate, there was a release of ornithine by rumen papillae indicating urea production. The tissues of rumen papillae appear to synthesize amino acids from expected carbon sources with ammonia or glutamate as nitrogen sources and to catabolize glutamine and arginine. The metabolism of amino acids by rumen papillae would contribute to the interchange of nitrogen between the rumen and the host.

scholarly journals Specific Phenotypic Traits ofStarmerella bacillarisRelated to Nitrogen Source Consumption and Central Carbon Metabolite Production during Wine Fermentation

2018 ◽  
Vol 84 (16) ◽  
Author(s):  
Vasileios Englezos ◽  
Luca Cocolin ◽  
Kalliopi Rantsiou ◽  
Anne Ortiz-Julien ◽  
Audrey Bloem ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acids ◽  
Fermentation Process ◽  
Nitrogen Sources ◽  
Starter Cultures ◽  
Wine Fermentation ◽  
Phenotypic Traits ◽  
Mixed Fermentation ◽  
Content Type ◽  
Central Carbon

ABSTRACTOver the last few years, the potential of non-Saccharomycesyeasts to improve the sensory quality of wine has been well recognized. In particular, the use ofStarmerella bacillarisin mixed fermentations withSaccharomyces cerevisiaewas reported as an appropriate way to enhance glycerol formation and reduce ethanol production. However, during sequential fermentation, many factors, such as the inoculation timing, strain combination, and physical and biochemical interactions, can affect yeast growth, the fermentation process, and/or metabolite synthesis. Among them, the availability of yeast-assimilable nitrogen (YAN), due to its role in the control of growth and fermentation, has been identified as a key parameter. Consequently, a comprehensive understanding of the metabolic specificities and the nitrogen requirements would be valuable to better exploit the potential ofStarm. bacillarisduring wine fermentation. In this study, marked differences in the consumption of the total and individual nitrogen sources were registered between the two species, while the twoStarm. bacillarisstrains generally behaved uniformly.Starm. bacillarisstrains are differentiated by their preferential uptake of ammonium compared with amino acids that are poorly assimilated or even produced (alanine). Otherwise, the non-Saccharomycesyeast exhibits low activity through the acetaldehyde pathway, which triggers an important redistribution of fluxes through the central carbon metabolic network. In particular, the formation of metabolites deriving from the two glycolytic intermediates glyceraldehyde-3-phosphate and pyruvate is substantially increased during fermentations byStarm. bacillaris. This knowledge will be useful to better control the fermentation process in mixed fermentation withStarm. bacillarisandS. cerevisiae.IMPORTANCEMixed fermentations using a controlled inoculation ofStarmerella bacillarisandSaccharomyces cerevisiaestarter cultures represent a feasible way to modulate wine composition that takes advantage of both the phenotypic specificities of the non-Saccharomycesstrain and the ability ofS. cerevisiaeto complete wine fermentation. However, according to the composition of grape juices, the consumption byStarm. bacillarisof nutrients, in particular of nitrogen sources, during the first stages of the process may result in depletions that further limit the growth ofS. cerevisiaeand lead to stuck or sluggish fermentations. Consequently, understanding the preferences of non-Saccharomycesyeasts for the nitrogen sources available in grape must together with their phenotypic specificities is essential for an efficient implementation of sequential wine fermentations withStarm. bacillarisandS. cerevisiaespecies. The results of our study demonstrate a clear preference for ammonium compared to amino acids for the non-Saccharomycesspecies. This finding underlines the importance of nitrogen sources, which modulate the functional characteristics of inoculated yeast strains to better control the fermentation process and product quality.

scholarly journals The Gal3p-Gal80p-Gal4p Transcription Switch of Yeast: Gal3p Destabilizes the Gal80p-Gal4p Complex in Response to Galactose and ATP

1999 ◽  
Vol 19 (11) ◽  
pp. 7828-7840 ◽  
Author(s):  
Alok Kumar Sil ◽  
Samina Alam ◽  
Ping Xin ◽  
Ly Ma ◽  
Melissa Morgan ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acids ◽  
Genetic Interaction ◽  
Transcription Activation ◽  
Full Length ◽  
Signal Transducer ◽  
Binding Peptide ◽  
Two Hybrid

ABSTRACT The Gal3, Gal80, and Gal4 proteins of Saccharomyces cerevisiae comprise a signal transducer that governs the galactose-inducible Gal4p-mediated transcription activation ofGAL regulon genes. In the absence of galactose, Gal80p binds to Gal4p and prohibits Gal4p from activating transcription, whereas in the presence of galactose, Gal3p binds to Gal80p and relieves its inhibition of Gal4p. We have found that immunoprecipitation of full-length Gal4p from yeast extracts coprecipitates less Gal80p in the presence than in the absence of Gal3p, galactose, and ATP. We have also found that retention of Gal80p by GSTG4AD (amino acids [aa] 768 to 881) is markedly reduced in the presence compared to the absence of Gal3p, galactose, and ATP. Consistent with these in vitro results, an in vivo two-hybrid genetic interaction between Gal80p and Gal4p (aa 768 to 881) was shown to be weaker in the presence than in the absence of Gal3p and galactose. These compiled results indicate that the binding of Gal3p to Gal80p results in destabilization of a Gal80p-Gal4p complex. The destabilization was markedly higher for complexes consisting of G4AD (aa 768 to 881) than for full-length Gal4p, suggesting that Gal80p relocated to a second site on full-length Gal4p. Congruent with the idea of a second site, we discovered a two-hybrid genetic interaction involving Gal80p and the region of Gal4p encompassing aa 225 to 797, a region of Gal4p linearly remote from the previously recognized Gal80p binding peptide within Gal4p aa 768 to 881.

The alpha subunit of initiation factor 2 is phosphorylated in vivo in the yeast Saccharomyces cerevisiae

1986 ◽  
Vol 6 (4) ◽  
pp. 1044-1049
Author(s):  
D P Romero ◽  
A E Dahlberg
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Carbon Sources ◽  
Relative Increase ◽  
Initiation Factor ◽  
Alpha Subunit ◽  
Yeast Saccharomyces Cerevisiae ◽  
Two Dimensional Gel Electrophoresis ◽  
Initiation Factor 2 ◽  
Reticulocyte Lysates

The phosphorylation state of the alpha subunit of initiation factor 2 (eIF-2 alpha) in Saccharomyces cerevisiae has been determined by two-dimensional gel electrophoresis and autoradiography of lysates from cultures grown under a variety of conditions. The alpha subunit was maintained in a phosphorylated state during logarithmic growth on fermentable and nonfermentable carbon sources, during starvation for an essential amino acid, during heat shock, during stationary phase, and during sporulation. Only when cells were starved for a carbon source for 2 h in 1 M sorbitol was eIF-2 alpha isolated in the nonphosphorylated state. This is in contrast with the studies in rabbit reticulocyte lysates, in which arrested protein synthesis was correlated with a relative increase in the extent of phosphorylation of eIF-2 alpha.

scholarly journals Influence of Glutamate on Growth, Sporulation, and Spore Properties of Bacillus cereus ATCC 14579 in Defined Medium

2005 ◽  
Vol 71 (6) ◽  
pp. 3248-3254 ◽  
Author(s):  
Ynte P. de Vries ◽  
Ratna D. Atmadja ◽  
Luc M. Hornstra ◽  
Willem M. de Vos ◽  
Tjakko Abee
Keyword(s):  
Amino Acids ◽  
Bacillus Cereus ◽  
Exponential Growth ◽  
Dipicolinic Acid ◽  
Carbon Sources ◽  
Nitrogen Sources ◽  
Defined Medium ◽  
Mother Cells ◽  
Almost All ◽  
Time Frames

ABSTRACT A chemically defined medium in combination with an airlift fermentor system was used to study the growth and sporulation of Bacillus cereus ATCC 14579. The medium contained six amino acids and lactate as the main carbon sources. The amino acids were depleted during exponential growth, while lactate was metabolized mainly during stationary phase. Two concentrations of glutamate were used: high (20 mM; YLHG) and low (2.5 mM; YLLG). Under both conditions, sporulation was complete and synchronous. Sporulation started and was completed while significant amounts of carbon and nitrogen sources were still present in the medium, indicating that starvation was not the trigger for sporulation. Analysis of amino acids and NH4 + in the culture supernatant showed that most of the nitrogen assimilated by the bacteria was taken up during sporulation. The consumption of glutamate depended on the initial concentration; in YLLG, all of the glutamate was used early during exponential growth, while in YLHG, almost all of the glutamate was used during sporulation. In YLLG, but not in YLHG, NH4 + was taken up by the cells during sporulation. The total amount of nitrogen used by the bacteria in YLLG was less than that used by the bacteria in YLHG, although a significant amount of NH4 + was present in the medium throughout sporulation. Despite these differences, growth and temporal expression of key sigma factors involved in sporulation were parallel, indicating that the genetic time frames of sporulation were similar under both conditions. Nevertheless, in YLHG, dipicolinic acid production started later and the spores were released from the mother cells much later than in YLLG. Notably, spores had a higher heat resistance when obtained after growth in YLHG than when obtained after growth in YLLG, and the spores germinated more rapidly and completely in response to inosine, l-alanine, and a combination of these two germinants.

THE UTILIZATION OF PURINES, PYRIMIDINES, AND INORGANIC NITROGENOUS COMPOUNDS BY EFFECTIVE AND INEFFECTIVE STRAINS OF RHIZOBIUM MELILOTI

1955 ◽  
Vol 1 (8) ◽  
pp. 668-674 ◽  
Author(s):  
D. C. Jordan ◽  
C. L. San Clemente
Keyword(s):  
Amino Acids ◽  
Carboxylic Acids ◽  
Ammonium Chloride ◽  
Rhizobium Meliloti ◽  
Synthetic Medium ◽  
Nitrogen Sources ◽  
Sole Source ◽  
Acid Media ◽  
Nitrogenous Compounds ◽  
Growth Initiation

Ammonium chloride was not utilized by three strains of Rhizobium meliloti as the sole source of nitrogen in a sucrose medium, unless either amino or certain non-nitrogenous carboxylic acids were also present. This was also essentially true for the utilization of nitrate, nitrite, purines, and pyrimidines, all of which are potentially able to form ammonia. These results may be interpreted on the assumption that washed cells of alfalfa – sweet clover rhizobia require, for growth initiation in a nitrogen-free medium, either preformed amino acids or compounds such as ammonia and certain carboxylic acids from which amino acids can be synthesized. Since α-ketoglutarate was extremely active in promoting growth in a medium containing ammonium chloride it was implied that the ammonia may be fixed by L-glutamic acid dehydrogenase activity, especially since this particular enzyme was located in these organisms. No aspartase activity could be demonstrated. The ineffective strain differed from the effective strains in that it was unable to use purines or pyrimidines as accessory nitrogen sources in amino acid media. This was a result of strain variation and it was not coupled with the state of ineffectiveness itself. A synthetic medium has been formulated for further growth studies on washed Rhizobium cells and for investigations on auxotrophic mutants of these bacteria.

scholarly journals Aca1 and Aca2, ATF/CREB Activators in Saccharomyces cerevisiae, Are Important for Carbon Source Utilization but Not the Response to Stress

2000 ◽  
Vol 20 (12) ◽  
pp. 4340-4349 ◽  
Author(s):  
M. Adelaida Garcia-Gimeno ◽  
Kevin Struhl
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Carbon Source ◽  
Target Genes ◽  
Carbon Sources ◽  
Biological Functions ◽  
Carbon Source Utilization ◽  
The Family ◽  
Response To Stress

ABSTRACT In Saccharomyces cerevisiae, the family of ATF/CREB transcriptional regulators consists of a repressor, Acr1 (Sko1), and two activators, Aca1 and Aca2. The AP-1 factor Gen4 does not activate transcription through ATF/CREB sites in vivo even though it binds these sites in vitro. Unlike ATF/CREB activators in other species, Aca1- and Aca2-dependent transcription is not affected by protein kinase A or by stress, and Aca1 and Aca2 are not required for Hog1-dependent salt induction of transcription through an optimal ATF/CREB site. Aca2 is important for a variety of biological functions including growth on nonoptimal carbon sources, and Aca2-dependent activation is modestly regulated by carbon source. Strains lacking Aca1 are phenotypically normal, but overexpression of Aca1 suppresses some defects associated with the loss of Aca2, indicating a functional overlap between Aca1 and Aca2. Acr1 represses transcription both by recruiting the Cyc8-Tup1 corepressor and by directly competing with Aca1 and Aca2 for target sites. Acr1 does not fully account for osmotic regulation through ATF/CREB sites, and a novel Hog1-dependent activator(s) that is not a bZIP protein is required for ATF/CREB site activation in response to high salt. In addition, Acr1 does not affect a number of phenotypes that arise from loss of Aca2. Thus, members of the S. cerevisiae ATF/CREB family have overlapping, but distinct, biological functions and target genes.

scholarly journals Management of Multiple Nitrogen Sources during Wine Fermentation by Saccharomyces cerevisiae

2017 ◽  
Vol 83 (5) ◽  
Author(s):  
Lucie Crépin ◽  
Nhat My Truong ◽  
Audrey Bloem ◽  
Isabelle Sanchez ◽  
Sylvie Dequin ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acids ◽  
Fermentation Process ◽  
De Novo ◽  
Nitrogen Sources ◽  
Wine Industry ◽  
Sensory Profile ◽  
Minor Role ◽  
Available Nitrogen ◽  
Intracellular Fate

ABSTRACT During fermentative growth in natural and industrial environments, Saccharomyces cerevisiae must redistribute the available nitrogen from multiple exogenous sources to amino acids in order to suitably fulfill anabolic requirements. To exhaustively explore the management of this complex resource, we developed an advanced strategy based on the reconciliation of data from a set of stable isotope tracer experiments with labeled nitrogen sources. Thus, quantifying the partitioning of the N compounds through the metabolism network during fermentation, we demonstrated that, contrary to the generally accepted view, only a limited fraction of most of the consumed amino acids is directly incorporated into proteins. Moreover, substantial catabolism of these molecules allows for efficient redistribution of nitrogen, supporting the operative de novo synthesis of proteinogenic amino acids. In contrast, catabolism of consumed amino acids plays a minor role in the formation of volatile compounds. Another important feature is that the α-keto acid precursors required for the de novo syntheses originate mainly from the catabolism of sugars, with a limited contribution from the anabolism of consumed amino acids. This work provides a comprehensive view of the intracellular fate of consumed nitrogen sources and the metabolic origin of proteinogenic amino acids, highlighting a strategy of distribution of metabolic fluxes implemented by yeast as a means of adapting to environments with changing and scarce nitrogen resources. IMPORTANCE A current challenge for the wine industry, in view of the extensive competition in the worldwide market, is to meet consumer expectations regarding the sensory profile of the product while ensuring an efficient fermentation process. Understanding the intracellular fate of the nitrogen sources available in grape juice is essential to the achievement of these objectives, since nitrogen utilization affects both the fermentative activity of yeasts and the formation of flavor compounds. However, little is known about how the metabolism operates when nitrogen is provided as a composite mixture, as in grape must. Here we quantitatively describe the distribution through the yeast metabolic network of the N moieties and C backbones of these nitrogen sources. Knowledge about the management of a complex resource, which is devoted to improvement of the use of the scarce N nutrient for growth, will be useful for better control of the fermentation process and the sensory quality of wines.

Sign in / Sign up

Export Citation Format

Share Document