scholarly journals The putative electrogenic nitrate-proton symport of the yeast Candida utilis. Comparison with the systems absorbing glucose or lactate

1985 ◽  
Vol 231 (2) ◽  
pp. 291-297 ◽  
Author(s):  
A A Eddy ◽  
P G Hopkins
Keyword(s):  
Amino Acids ◽  
Energy Metabolism ◽  
Candida Utilis ◽  
Membrane Depolarization ◽  
Yeast Cells ◽  
Charge Balance ◽  
Proton Symport ◽  
Limiting Nutrient ◽  
Proton Uptake ◽  
Aerobic Energy Metabolism

Strain N.C.Y.C. 193 of Candida utilis was grown aerobically at 30 degrees C with nitrate as limiting nutrient in a chemostat. The washed yeast cells depleted of ATP absorbed up to 5 nmol of nitrate/mg dry wt. of yeast. At pH 4-6, extra protons and nitrate entered the yeast cells together, in a ratio of about 2:1. Charge balance was maintained by an outflow of about 1 equiv. of K+. Nitrate stimulated the uptake of about 1 proton equivalent during glycolysis or aerobic energy metabolism. Studies with 3,3′-dipropylthiadicarbocyanine indicated that the proton-linked absorption of nitrate, amino acids or glucose depolarized the yeast cells. Proton uptake along with lactate led neither to net expulsion of K+ nor to membrane depolarization.

scholarly journals Viability and Versatility of the Yeast Cell

2004 ◽  
Vol 12 (3) ◽  
pp. 30-33
Author(s):  
Michelle J. Henry-Stanley ◽  
Carol L. Wells
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acids ◽  
Yeast Cell ◽  
Candida Utilis ◽  
Paper Industry ◽  
Yeast Cells ◽  
Distilled Spirits ◽  
Eukaryotic Microorganisms ◽  
Brewers Yeast ◽  
Soil And Water

Yeasts are single-celled eukaryotic microorganisms (generally about 5 to 10 microns in diameter) that divide by a budding process and are classified with the fungi. Yeast cells are ubiquitous in our environment and can be found on plants and in soil and water. Yeasts have considerable importance Ln industrial and agricultural settings,Saccharomyces cerevisiae(Figure 1) is also known as “bakers yeast” or “brewers yeast.” Specific strains of yeast are used to make pastries, bread, beer, ale, wine, distilled spirits, and industrial alcohol. In the paper industry,Candida utilisis used to break down die sugars from processed wood pulp. Yeast cells are also nutritious. In some societies, “cloudy” beer (containing yeast cells) provides essential B vitamins, minerals, and amino acids.

scholarly journals The concentration of amino acids by yeast cells depleted of adenosine triphosphate

1970 ◽  
Vol 120 (4) ◽  
pp. 853-858 ◽  
Author(s):  
A. A. Eddy ◽  
K. Backen ◽  
G. Watson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Energy Metabolism ◽  
Adenosine Triphosphate ◽  
Physical Process ◽  
Ionic Species ◽  
Yeast Cells ◽  
Atp Content ◽  
Chemically Modified ◽  
Endogenous Amino Acids

1. The ATP content of preparations of a strain of Saccharomyces carlsbergensis was lowered below 0.3nmol/mg of yeast by starving the yeast cells in the presence of both antimycin and 5mm-deoxyglucose. 2. When the depleted cells were put at pH4.5 with glycine up to about 20nmol of the amino acid/mg of yeast was absorbed without being chemically modified. The mechanism did not depend on an exchange with endogenous amino acids. 3. The concentration of the absorbed glycine could apparently reach 100–200 times that outside the cells. 4. Replacement of the cellular K+ by Na+ almost stopped amino acid absorption in the presence of antimycin and deoxyglucose, but not in their absence. 5. It is suggested that, when energy metabolism itself had stopped, a purely physical process, namely the movements of H+ and K+ into and out of the yeast respectively, served to concentrate the amino acids in the cells. Both ionic species appear to be co-substrates of the system transporting amino acids.

scholarly journals Stoicheiometrical proton and potassium ion movements accompanying the absorption of amino acids by the yeast Saccharomyces carlsbergensis

1971 ◽  
Vol 122 (5) ◽  
pp. 701-711 ◽  
Author(s):  
A. A. Eddy ◽  
J. A. Nowacki
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Energy Metabolism ◽  
Concentration Gradient ◽  
Metabolic Inhibitors ◽  
Ion Pump ◽  
Saccharomyces Carlsbergensis ◽  
Ion Movements ◽  
Proton Uptake ◽  
Amino Acid Carrier

1. Proton uptake into the yeast Saccharomyces carlsbergensis, was studied at pH4.5–5.5 in the presence of both antimycin and 2-deoxyglucose to inhibit energy metabolism. Previous work had shown that the cells then absorbed about 20nmol of glycine or l-phenylalanine against a considerable amino acid concentration gradient. The addition of the amino acid immediately stimulated the rate of uptake of protons two- to three-fold. About 2 extra equivalents of H+ accompanied a given amount of the amino acids into the yeast preparations exposed to the metabolic inhibitors for 2–4min and about 1.2 equivalents after 20min exposure. 2. Analogous observations were made during serial additions of glycine, l-phenylalanine, l-leucine and l-lysine to preparations lacking the metabolic inhibitors and deficient in substrates needed for energy metabolism. In fresh cellular preparations the influx of glycine was then closely coupled to a stimulated flow of 2.1 equiv. of H+ into the yeast. A similar number of K+ ions left the cells. About 30% of the extra protons was subsequently ejected from the yeast. Deoxyglucose and antimycin together inhibited the ejection of protons. When the yeast had been fed with glucose energy metabolism was stimulated and almost as many protons as were absorbed with the amino acid were apparently ejected again. 3. Yeast preparations containing Na+, instead of K+, as the principal cation absorbed about 1 extra equivalent of H+ after the addition of phenylalanine, glycine or leucine. This response was not observed in the presence of both deoxyglucose and antimycin. 4. The observations show that H+ and, in certain circumstances, K+ are co-substrates in the transport of the amino acids into the yeast. An analogy is drawn with the roles of Na+ and K+ as co-substrates in certain mammalian systems. The results lead to various models relating the physical flow of the co-substrate ions on the amino acid carrier to the transduction of chemical energy in an associated ion pump forming part of the mechanism for transporting amino acids into the yeast.

A comparison of fuel preferences of mitochondria from vertebrates and invertebrates

1990 ◽  
Vol 68 (7) ◽  
pp. 1337-1349 ◽  
Author(s):  
C. D. Moyes ◽  
R. K. Suarez ◽  
P. W. Hochachka ◽  
J. S. Ballantyne
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Fatty Acids ◽  
Energy Metabolism ◽  
Ketone Bodies ◽  
Mitochondrial Enzymes ◽  
Tissue Specific ◽  
Isolated Mitochondria ◽  
Mitochondrial Oxidation ◽  
Aerobic Energy Metabolism

Knowledge of tissue-specific mitochondrial properties is important in understanding cellular aerobic energy metabolism. Studies employing isolated mitochondria offer the advantage of direct and controlled manipulation of extramitochondrial conditions, while minimizing disruption of interactions between mitochondrial enzymes, transporters, and membranes. In this review, we compare the oxidative properties of mitochondria isolated from liver, heart, and skeletal muscle of vertebrates and invertebrates. The observed differences between tissues and species in the capacities for mitochondrial oxidation of fatty acids, ketone bodies, pyruvate, and amino acids reflect fundamentally different adaptations for the assimilation, storage, and utilization of metabolic fuels.

scholarly journals The stoicheiometry of the absorption of protons with phosphate and L-glutamate by yeasts of the genus Saccharomyces

1975 ◽  
Vol 146 (3) ◽  
pp. 705-712 ◽  
Author(s):  
M Cockburn ◽  
P Earnshaw ◽  
A A Eddy
Keyword(s):  
Energy Metabolism ◽  
Extracellular Enzymes ◽  
Yeast Cells ◽  
Phosphate Esters ◽  
Charge Balance ◽  
Washed Cell ◽  
Ph Changes ◽  
Principal Source

1. A study was made of the pH changes occurring when 0.1-4 mumol of glutamate, phosphate and certain phosphate esters was added at about pH 4.8 to washed cell preparations (50 mg dry wt.) of strains of Saccharomyces. The system also contained deoxyglucose and antimycin to inhibit energy metabolism and so prevent proton ejection from the yeast. 2. A strain of Sacc. carlsbergensis was grown in a chemostat with a limiting supply of phosphate in order to enhance the subsequent rate of phosphate transfer into the yeast. These preparations absorbed 0.2 mumol of phosphate with about 3 equiv. of protons/mol of phosphate. The charge balance was maintained by the efflux of 2 equiv. of K-+ from the yeast. 3. Larger amounts of phosphate were absorbed with fewer proton equivalents. 4. Arsenate and phosphate caused similar pH changes. 5. Glucose 6-phosphate, ATP and certain order phosphate esters each initiated a rise in pH, possibly because hydrolytic extracellular enzymes released phosphate that was subsequently absorbed. 6. Four strains of yeast were grown with glutamate as principal source of nitrogen. Each absorbed extra protons in the presence of L-glutamate. 7. One of them, a strain of Sacc. cerevisiae, absorbed 0.2 mumol of glutamate with 3equiv. of protons/mol of glutamate, and in these circumstances 1-2 equiv. of K-+ left the yeast cells. 8. The role of ionic gradients in the transport of these anions is discussed.

Heterogeneity of Size and Distribution of Intramembrane Particles in the Plasma Membrane of Yeast

1977 ◽  
Vol 35 ◽  
pp. 596-597
Author(s):  
E. Keyhani
Keyword(s):  
Plasma Membrane ◽  
Candida Utilis ◽  
Synthetic Medium ◽  
Freeze Fracture ◽  
Translational Diffusion ◽  
Yeast Cells ◽  
Distilled Water ◽  
Intramembrane Particles ◽  
The Matrix ◽  
Water Cell

The matrix of biological membranes consists of a lipid bilayer into which proteins or protein aggregates are intercalated. Freeze-fracture techni- ques permit these proteins, perhaps in association with lipids, to be visualized in the hydrophobic regions of the membrane. Thus, numerous intramembrane particles (IMP) have been found on the fracture faces of membranes from a wide variety of cells (1-3). A recognized property of IMP is their tendency to form aggregates in response to changes in experi- mental conditions (4,5), perhaps as a result of translational diffusion through the viscous plane of the membrane. The purpose of this communica- tion is to describe the distribution and size of IMP in the plasma membrane of yeast (Candida utilis).Yeast cells (ATCC 8205) were grown in synthetic medium (6), and then harvested after 16 hours of culture, and washed twice in distilled water. Cell pellets were suspended in growth medium supplemented with 30% glycerol and incubated for 30 minutes at 0°C, centrifuged, and prepared for freeze-fracture, as described earlier (2,3).

Insertions of up to 17 amino acids into a region of alpha-tubulin do not disrupt function in vivo

1987 ◽  
Vol 7 (10) ◽  
pp. 3799-3805
Author(s):  
P J Schatz ◽  
G E Georges ◽  
F Solomon ◽  
D Botstein
Keyword(s):  
Amino Acids ◽  
Variable Region ◽  
Yeast Cells ◽  
Meiotic Spindle ◽  
Nuclear Movement ◽  
Yeast Saccharomyces Cerevisiae ◽  
Alpha Tubulin ◽  
Essential Components ◽  
Altered Proteins

Microtubules in yeasts are essential components of the mitotic and meiotic spindle and are necessary for nuclear movement during cell division and mating. The yeast Saccharomyces cerevisiae has two alpha-tubulin genes, TUB1 and TUB3, either of which alone is sufficient for these processes when present in a high enough copy number. Comparisons of sequences from several species reveals the presence of a variable region near the amino terminus of alpha-tubulin proteins. We perturbed the structure of this region in TUB3 by inserting into it 3, 9, or 17 amino acids and tested the ability of these altered proteins to function as the only alpha-tubulin protein in yeast cells. We found that each of these altered proteins was sufficient on its own for mitotic growth, mating, and methods of yeast. We conclude that this region can tolerate considerable variation without losing any of the highly conserved functions of alpha-tubulin. Our results suggest that variability in this region occurs because it can be tolerated, not because it specifies an important function for the protein.

The immunosuppressant FK506 inhibits amino acid import in Saccharomyces cerevisiae

1993 ◽  
Vol 13 (8) ◽  
pp. 5010-5019 ◽  
Author(s):  
J Heitman ◽  
A Koller ◽  
J Kunz ◽  
R Henriquez ◽  
A Schmidt ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acids ◽  
Amino Acid ◽  
Cyclosporin A ◽  
Secretory Pathway ◽  
Yeast Cells ◽  
Amino Acid Transporters ◽  
Yeast Saccharomyces Cerevisiae ◽  
Eukaryotic Microorganisms

The immunosuppressants cyclosporin A, FK506, and rapamycin inhibit growth of unicellular eukaryotic microorganisms and also block activation of T lymphocytes from multicellular eukaryotes. In vitro, these compounds bind and inhibit two different types of peptidyl-prolyl cis-trans isomerases. Cyclosporin A binds cyclophilins, whereas FK506 and rapamycin bind FK506-binding proteins (FKBPs). Cyclophilins and FKBPs are ubiquitous, abundant, and targeted to multiple cellular compartments, and they may fold proteins in vivo. Previously, a 12-kDa cytoplasmic FKBP was shown to be only one of at least two FK506-sensitive targets in the yeast Saccharomyces cerevisiae. We find that a second FK506-sensitive target is required for amino acid import. Amino acid-auxotrophic yeast strains (trp1 his4 leu2) are FK506 sensitive, whereas prototrophic strains (TRP1 his4 leu2, trp1 HIS4 leu2, and trp1 his4 LEU2) are FK506 resistant. Amino acids added exogenously to the growth medium mitigate FK506 toxicity. FK506 induces GCN4 expression, which is normally induced by amino acid starvation. FK506 inhibits transport of tryptophan, histidine, and leucine into yeast cells. Lastly, several genes encoding proteins involved in amino acid import or biosynthesis confer FK506 resistance. These findings demonstrate that FK506 inhibits amino acid import in yeast cells, most likely by inhibiting amino acid transporters. Amino acid transporters are integral membrane proteins which import extracellular amino acids and constitute a protein family sharing 30 to 35% identity, including eight invariant prolines. Thus, the second FK506-sensitive target in yeast cells may be a proline isomerase that plays a role in folding amino acid transporters during transit through the secretory pathway.

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