scholarly journals Yeast Mutants Deficient in ER-Associated Degradation of the Z Variant of Alpha-1-Protease Inhibitor

Genetics ◽  
1996 ◽  
Vol 144 (4) ◽  
pp. 1355-1362 ◽  
Author(s):  
Ardythe A McCracken ◽  
Igor V Karpichev ◽  
James E Ernaga ◽  
Eric D Werner ◽  
Andrew G Dillin ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Degradation ◽  
Proteinase Inhibitor ◽  
Parent Strain ◽  
Mendelian Inheritance ◽  
Wild Type ◽  
Mutant Strains ◽  
Complementation Groups ◽  
Yeast Mutants ◽  
Wild Type Yeast

Saccharomyces cerevisiae mutants deficient in degradation of alpha-1-proteinase inhibitor Z (A1PiZ) have been isolated and genetically characterized. Wild-type yeast expressing A1PiZ synthesize an ER form of this protein that is rapidly degraded by an intracellular proteolytic process known as ER-associated protein degradation (ERAD). The mutant strains were identified after treatment with EMS using a colony blot immunoassay to detect colonies that accumulated high levels of A1PiZ. A total of 120,000 colonies were screened and 30 putative mutants were identified. The level of A1PiZ accumulation in these mutants, measured by ELISA, ranged from two to 11 times that of A1PiZ in the parent strain. Further studies demonstrated that the increased levels of A1PiZ in most of the mutant strains was not the result of defective secretion or elevated A1PiZ mRNA. Pulse chase experiments indicated that A1PiZ was stabilized in several strains, evidence that these mutants are defective in ER-associated protein degradation. Genetic analyses revealed that most of the mutations were recessive, ∼30% of the mutants characterized conformed to simple Mendelian inheritance, and at least seven complementation groups were identified.

Evolution of ethylene by Saccharomyces cerevisiae as influenced by the carbon source for growth and the presence of air

1978 ◽  
Vol 24 (6) ◽  
pp. 637-642 ◽  
Author(s):  
K. C. Thomas ◽  
Mary Spencer
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Carbon Source ◽  
Ethylene Production ◽  
Atp Synthesis ◽  
Yeast Cells ◽  
Yeast Culture ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Absolute Requirement ◽  
Wild Type Yeast

Effects of the carbon source and oxygen on ethylene production by the yeast Saccharomyces cerevisiae have been studied. The amounts of ethylene evolved by the yeast culture were less than those detected in the blank (an equal volume of uninoculated medium), suggesting a net absorption of ethylene by the yeast cells. Addition of glucose to the lactate-grown yeast culture induced ethylene production. This glucose-induced stimulation of ethylene production was inhibited to a great extent by cycloheximide. Results suggested that the yeast cells in the presence of glucose synthesized an ethylene precursor and passed it into the medium. The conversion of this precursor to ethylene might be stimulated by oxygen. The fact that ethylene was produced by the yeast growing anaerobically and also by respiration-deficient mutants isolated from the wild-type yeast suggested that mitochondrial ATP synthesis was not an absolute requirement for ethylene biogenesis.

scholarly journals The effect of calnexin deletion on the expression level of PDI in Saccharomyces cerevisiae under heat stress conditions

2008 ◽  
Vol 13 (1) ◽  
Author(s):  
Huili Zhang ◽  
Jianwei He ◽  
Yanyan Ji ◽  
Akio Kato ◽  
Youtao Song
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Growth Rate ◽  
Heat Stress ◽  
Protein Expression ◽  
Molecular Chaperone ◽  
Mrna Level ◽  
Stress Conditions ◽  
Mrna Levels ◽  
Wild Type ◽  
Wild Type Yeast

AbstractWe cultured calnexin-disrupted and wild-type Saccharomyces cerevisiae strains under conditions of heat stress. The growth rate of the calnexin-disrupted yeast was almost the same as that of the wild-type yeast under those conditions. However, the induced mRNA level of the molecular chaperone PDI in the ER was clearly higher in calnexin-disrupted S. cerevisiae relative to the wild type at 37°C, despite being almost the same in the two strains under normal conditions. The western blotting analysis for PDI protein expression in the ER yielded results that show a parallel in their mRNA levels in the two strains. We suggest that PDI may interact with calnexin under heat stress conditions, and that the induction of PDI in the ER can recover part of the function of calnexin in calnexin-disrupted yeast, and result in the same growth rate as in wild-type yeast.

scholarly journals Peroxisome Maintenance Depends on De Novo Peroxisome Formation in Yeast Mutants Defective in Peroxisome Fission and Inheritance

2019 ◽  
Vol 20 (16) ◽  
pp. 4023 ◽  
Author(s):  
Justyna P. Wróblewska ◽  
Ida J. van der Klei
Keyword(s):  
De Novo ◽  
Hansenula Polymorpha ◽  
Yeast Cells ◽  
Wild Type ◽  
Double Deletion ◽  
Mother Cells ◽  
Yeast Mutants ◽  
Rescue Mechanism ◽  
Wild Type Yeast ◽  
In Cells

There is an ongoing debate on how peroxisomes form: by growth and fission of pre-existing peroxisomes or de novo from another membrane. It has been proposed that, in wild type yeast cells, peroxisome fission and careful segregation of the organelles over mother cells and buds is essential for organelle maintenance. Using live cell imaging we observed that cells of the yeast Hansenula polymorpha, lacking the peroxisome fission protein Pex11, still show peroxisome fission and inheritance. Also, in cells of mutants without the peroxisome inheritance protein Inp2 peroxisome segregation can still occur. In contrast, peroxisome fission and inheritance were not observed in cells of a pex11 inp2 double deletion strain. In buds of cells of this double mutant, new organelles likely appear de novo. Growth of pex11 inp2 cells on methanol, a growth substrate that requires functional peroxisomes, is retarded relative to the wild type control. Based on these observations we conclude that in H. polymorpha de novo peroxisome formation is a rescue mechanism, which is less efficient than organelle fission and inheritance to maintain functional peroxisomes.

Expression of a mammalian Na+/H+ antiporter in Saccharomyces cerevisiae

1999 ◽  
Vol 77 (1) ◽  
pp. 25-31 ◽  
Author(s):  
Mónica Montero-Lomelí ◽  
Anna L Okorokova Façanha.
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Heat Shock ◽  
Subcellular Fractionation ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Coding Region ◽  
Phosphatidylcholine Liposomes ◽  
Yeast Transformants ◽  
Wild Type Yeast ◽  
Membrane Region

The basolateral Na+/H+ antiporter (NHE) from LLC-PK1 cells was expressed in Saccharomyces cerevisiae. Two different strategies were tested for expression. In the first, we used a yeast strain that contains a temperature-sensitive mutation in the SEC-6 gene, whose product is required for the fusion of secretory vesicles with the plasma membrane. This strain was transformed with a vector containing the coding region of the NHE1 isoform under control of a heat shock (HS) promoter (pYNHE1-HS). In the second strategy, we replaced the heat shock promoter from pYNHE1-HS with a galactose (GAL) promoter (pYNHEI-GAL) and transformed wild-type yeast. In both cases, Northern blots demonstrated a transcript that hybridized against a probe containing the membrane region of the exchanger. When an antibody against the last 40 amino acids of the carboxy-terminus of NHE1 was used for immuno-blots, a protein with a Mr of 73 000 was seen in total membranes from both yeast transformants. Subcellular fractionation revealed that NHE1 was expressed in the endoplasmic reticulum. In the case of the pYNHEI-GAL transformant, the 100 000 × g membrane pellet was reconstituted in phosphatidylcholine liposomes, and ethylisopropyl-amiloride-sensitive Na+/H+ exchange was observed. These results have paved the way for expression of the Na+/H+ exchanger in a genetically well-known microorganism.Key words: Na+/H+ exchanger, NHE1, expression, yeast.

scholarly journals Roles of His-Rich Hpn and Hpn-Like Proteins in Helicobacter pylori Nickel Physiology

2007 ◽  
Vol 189 (11) ◽  
pp. 4120-4126 ◽  
Author(s):  
Susmitha Seshadri ◽  
Stéphane L. Benoit ◽  
Robert J. Maier
Keyword(s):  
Parent Strain ◽  
Urease Activity ◽  
Ph Effect ◽  
Cadmium Toxicity ◽  
Activity Levels ◽  
Wild Type ◽  
Dual Roles ◽  
Individual Gene ◽  
Protein Mutants ◽  
Mutant Strains

ABSTRACT Individual gene-targeted hpn and hpn-like mutants and a mutant with mutations in both hpn genes were more sensitive to nickel, cobalt, and cadmium toxicity than was the parent strain, with the hpn-like strain showing the most metal sensitivity of the two individual His-rich protein mutants. The mutant strains contained up to eightfold more urease activity than the parent under nickel-deficient conditions, and the parent strain was able to achieve mutant strain activity levels by nickel supplementation. The mutants contained 3- to 4-fold more and the double mutant about 10-fold more Ni associated with their total urease pools, even though all of the strains expressed similar levels of total urease protein. Hydrogenase activities in the mutants were like those in the parent strain; thus, hydrogenase is fully activated under nickel-deficient conditions. The histidine-rich proteins appear to compete with the Ni-dependent urease maturation machinery under low-nickel conditions. Upon lowering the pH of the growth medium from 7.3 to 5, the wild-type urease activity increased threefold, but the activity in the three mutant strains was relatively unaffected. This pH effect was attributed to a nickel storage role for the His-rich proteins. Under low-nickel conditions, the addition of a nickel chelator did not significantly affect the urease activity of the wild type but decreased the activity of all of the mutants, supporting a role for the His-rich proteins as Ni reservoirs. These nickel reservoirs significantly impact the active urease activities achieved. The His-rich proteins play dual roles, as Ni storage and as metal detoxification proteins, depending on the exogenous nickel levels.

scholarly journals Discovery of a Modified Transcription Factor Endowing Yeasts with Organic-Solvent Tolerance and Reconstruction of an Organic-Solvent-Tolerant Saccharomyces cerevisiae Strain

2008 ◽  
Vol 74 (13) ◽  
pp. 4222-4225 ◽  
Author(s):  
Ken Matsui ◽  
Shinya Teranishi ◽  
Shohei Kamon ◽  
Kouichi Kuroda ◽  
Mitsuyoshi Ueda
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Transcription Factor ◽  
Organic Solvent ◽  
Carbonyl Compounds ◽  
Solvent Tolerance ◽  
Wild Type ◽  
Organic Solvent Tolerance ◽  
Organic Solvent Tolerant ◽  
Solvent Tolerant ◽  
Wild Type Yeast

ABSTRACT Organic-solvent tolerance in Saccharomyces cerevisiae strain KK-211, which was first isolated as an organic-solvent-tolerant strain, depends on point mutation (R821S) of the transcription factor Pdr1p. The integration of the PDR1 R821S mutation into wild-type yeast results in organic-solvent tolerance, and the PDR1 R821S mutant can reduce carbonyl compounds in organic solvents.

scholarly journals Biological role of the general control of amino acid biosynthesis in Saccharomyces cerevisiae.

1981 ◽  
Vol 1 (7) ◽  
pp. 584-593 ◽  
Author(s):  
P Niederberger ◽  
G Miozzari ◽  
R Hütter
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acid ◽  
Amino Acid Biosynthesis ◽  
Wild Type ◽  
General Control ◽  
Acid Biosynthesis ◽  
Mutant Strains ◽  
In The Wild ◽  
Amino Acid Imbalance

The biological role of the "general control of amino acid biosynthesis" has been investigated by analyzing growth and enzyme levels in wild-type, bradytrophic, and nonderepressing mutant strains of Saccharomyces cerevisiae. Amino acid limitation was achieved by using either bradytrophic mutations or external amino acid imbalance. In the wild-type strain noncoordinate derepression of enzymes subject to the general control has been found. Derepressing factors were in the order of 2 to 4 in bradytrophic mutant strains grown under limiting conditions and only in the order of 1.5 to 2 under the influence of external amino acid imbalance. Nonderepressing mutations led to slower growth rates under conditions of amino acid limitation, and no derepression of enzymes under the general control was observed. The amino acid pools were found to be very similar in the wild type and in nonderepressing mutant strains under all conditions tested. Our results indicate that the general control affects all branched amino acid biosynthetic pathways, namely, those of the aromatic amino acids and the aspartate family, the pathways for the basic amino acids lysine, histidine, and arginine, and also the pathways of serine and valine biosyntheses.

scholarly journals Yeast mutants sensitive to antimicrotubule drugs define three genes that affect microtubule function.

Genetics ◽  
1990 ◽  
Vol 124 (2) ◽  
pp. 251-262 ◽  
Author(s):  
T Stearns ◽  
M A Hoyt ◽  
D Botstein
Keyword(s):  
Chromosome Loss ◽  
Gene Products ◽  
Wild Type ◽  
Tubulin Genes ◽  
New Genes ◽  
Complementation Groups ◽  
Yeast Mutants ◽  
Antimicrotubule Drugs ◽  
Tubulin Mutations ◽  
Microtubule Function

Abstract Three new genes affecting microtubule function in Saccharomyces cerevisiae were isolated by screening for mutants displaying supersensitivity to the antimicrotubule drug benomyl. Such mutants fall into six complementation groups: TUB1, TUB2 and TUB3, the three tubulin genes of yeast, and three new genes, which we have named CIN1, CIN2 and CIN4. Mutations in each of the CIN genes were also independently isolated by screening for mutants with increased rates of chromosome loss. Strains bearing mutations in the CIN genes are approximately tenfold more sensitive than wild type to both benomyl and to the related antimicrotubule drug, nocodazole. This phenotype is recessive for all alleles isolated. The CIN1, CIN2 and CIN4 genes were cloned by complementation of the benomyl-supersensitive phenotype. Null mutants of each of the genes are viable, and have phenotypes similar to those of the point mutants. Genetic evidence for the involvement of the CIN gene products in microtubule function comes from the observation that some tubulin mutations are suppressed by cin mutations, while other tubulin mutations are lethal in combination with cin mutations. Additional genetic experiments with cin mutants suggest that the three genes act together in the same pathway or structure to affect microtubule function.

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