ESR determination of membrane order parameter in yeast sterol mutants

Lees, N. Douglas; Bard, Martin; Kemple, Marvin D.; Haak, Richard A.; Kleinhans, F.W.

doi:10.1016/0005-2736(79)90302-x

Cited by 54 publications

(30 citation statements)

References 16 publications

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“…This correlated with previous results showing that cells entering industrial fermentations are depleted for ergosterol (9) and that, in the presence of oxygen, ergosterol starvation induces expression of the early ERG genes (19,52). Ergosterol has been shown to have vital functions in Saccharomyces cerevisiae cells affecting membrane fluidity and permeability and providing the "sparking function" that is thought to be involved in the progression into the G 1 phase of the cell cycle (5,15,33). It has been proposed that the steps catalyzed by Erg3p and Erg6p are essential for the sparking function (15,34,50).…”

Section: Vol 69 2003 Gene Expression Of Brewer's Yeast During Fermesupporting

confidence: 89%

Yeast Genome-Wide Expression Analysis Identifies a Strong Ergosterol and Oxidative Stress Response during the Initial Stages of an Industrial Lager Fermentation

Higgins

Beckhouse

Oliver³

et al. 2003

Appl Environ Microbiol

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Genome-wide expression analysis of an industrial strain of Saccharomyces cerevisiae during the initial stages of an industrial lager fermentation identified a strong response from genes involved in the biosynthesis of ergosterol and oxidative stress protection. The induction of the ERG genes was confirmed by Northern analysis and was found to be complemented by a rapid accumulation of ergosterol over the initial 6-h fermentation period. From a test of the metabolic activity of deletion mutants in the ergosterol biosynthesis pathway, it was found that ergosterol is an important factor in restoring the fermentative capacity of the cell after storage. Additionally, similar ERG10 and TRR1 gene expression patterns over the initial 24-h fermentation period highlighted a possible interaction between ergosterol biosynthesis and the oxidative stress response. Further analysis showed that erg mutants producing altered sterols were highly sensitive to oxidative stress-generating compounds. Here we show that genome-wide expression analysis can be used in the commercial environment and was successful in identifying environmental conditions that are important in industrial yeast fermentation.Yeast are subjected to many types of stress and metabolic challenges throughout industrial fermentation processes. These range from the physical (pressure and shearing) to the chemical, such as osmotic shock, oxidative stress, and secondary metabolite toxicity (3). Yeast fermentation is an ancient process, and years of exposure to these conditions have resulted in industrial yeast strains that have evolved mechanisms to adapt to them. However, with the advent of new processes that increase yields or are more cost-effective, different and increased demands have been placed on the yeast. This can lead to conditions that overwhelm yeast defenses, causing defective fermentations with poor sugar utilization, reduced ethanol production, and the synthesis of poor flavor qualities (21,38,55). Increased stress has also been found to have an impact on the activity and longevity properties of the yeast and therefore affect their performance in subsequent fermentations (30,47,53).To better understand the determinants of defective brews, research is often carried out by changing single parameters in model systems that can be reliably reproduced. This process has been very successful in determining the molecular mechanisms involved in protection against individual stresses. However, industrial fermentations are dynamic in nature, with multiple stresses or biological changes interacting simultaneously to cause the physiological traits of the yeast or fermentation parameters. Thus, studying the effect of individual stresses on yeast does not give the full picture of the important environmental parameters in fermentation.

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Section: Vol 69 2003 Gene Expression Of Brewer's Yeast During Fermesupporting

confidence: 89%

Yeast Genome-Wide Expression Analysis Identifies a Strong Ergosterol and Oxidative Stress Response during the Initial Stages of an Industrial Lager Fermentation

Higgins

Beckhouse

Oliver³

et al. 2003

Appl Environ Microbiol

View full text Add to dashboard Cite

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“…On the basis of these results, we speculated that the PAU genes may be induced in response to a more general effect on membranes, as both heme and sterols are known to decrease membrane fluidity (Lees et al 1979;Shviro et al 1982;Ginsburg and Demel 1984;Schmitt et al 1993;Berg et al 2002;Abe et al 2009). To test directly whether changing membrane fluidity contributes to PAU induction, we employed dimethyl sulfoxide (DMSO) and glycerol, both of which are known to decrease membrane fluidity (Surewicz 1984;Lewis et al 1994;Gurtovenko and Anwar 2007).…”

Section: Resultsmentioning

confidence: 98%

The Hog1 Mitogen-Activated Protein Kinase Mediates a Hypoxic Response inSaccharomyces cerevisiae

2011

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We have studied hypoxic induction of transcription by studying the seripauperin (PAU ) genes of Saccharomyces cerevisiae. Previous studies showed that PAU induction requires the depletion of heme and is dependent upon the transcription factor Upc2. We have now identified additional factors required for PAU induction during hypoxia, including Hog1, a mitogen-activated protein kinase (MAPK) whose signaling pathway originates at the membrane. Our results have led to a model in which heme and ergosterol depletion alters membrane fluidity, thereby activating Hog1 for hypoxic induction. Hypoxic activation of Hog1 is distinct from its previously characterized response to osmotic stress, as the two conditions cause different transcriptional consequences. Furthermore, Hog1-dependent hypoxic activation is independent of the S. cerevisiae general stress response. In addition to Hog1, specific components of the SAGA coactivator complex, including Spt20 and Sgf73, are also required for PAU induction. Interestingly, the mammalian ortholog of Spt20, p38IP, has been previously shown to interact with the mammalian ortholog of Hog1, p38. Taken together, our results have uncovered a previously unknown hypoxic-response pathway that may be conserved throughout eukaryotes.

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“…Some reports have supported the idea that factors affecting membrane order are crucial for tryptophan uptake. For example, membrane fluidity as measured by electron spin resonance is significantly lowered in ergosterol-deficient mutants (44), and the erg6 mutant, which is defective in ergosterol biosynthesis, has a defect in tryptophan uptake, suggesting that appropriate membrane order and/or ergosterol are required for normal tryptophan uptake activity (25). The addition of the volatile anesthetic isoflurane impairs cell growth in trp1 strains, probably by disrupting membrane order (48).…”

Section: Discussionmentioning

confidence: 99%

Pressure-Induced Differential Regulation of the Two Tryptophan Permeases Tat1 and Tat2 by Ubiquitin Ligase Rsp5 and Its Binding Proteins, Bul1 and Bul2

Abe

Iida

2003

Molecular and Cellular Biology

110

178

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Tryptophan uptake appears to be the Achilles' heel in yeast physiology, since under a variety of seemingly diverse toxic conditions, it becomes the limiting factor for cell growth. When growing cells of Saccharomyces cerevisiae are subjected to high hydrostatic pressure, tryptophan uptake is down-regulated, leading to cell cycle arrest in the G 1 phase. Here we present evidence that the two tryptophan permeases Tat1 and Tat2 are differentially regulated by Rsp5 ubiquitin ligase in response to high hydrostatic pressure. Analysis of highpressure growth mutants revealed that the HPG1 gene was allelic to RSP5. The HPG1 mutation or the bul1⌬ bul2⌬ double mutation caused a marked increase in the steady-state level of Tat2 but not of Tat1, although both permeases were degraded at high pressure in an Rsp5-dependent manner. There were marked differences in subcellular localization. Tat1 localized predominantly in the plasma membrane, whereas Tat2 was abundant in the internal membranes. Moreover, Tat1 was associated with lipid rafts, whereas Tat2 localized in bulk lipids. Surprisingly, Tat2 became associated with lipid rafts upon the occurrence of a ubiquitination defect. These results suggest that ubiquitination is an important determinant of the localization and regulation of these tryptophan permeases. Determination of the activation volume (⌬V ) for Tat1-and Tat2-mediated tryptophan uptake (89.3 and 50.8 ml/mol, respectively) revealed that both permeases are highly sensitive to membrane perturbation and that Tat1 rather than Tat2 is likely to undergo a dramatic conformational change during tryptophan import. We suggest that hydrostatic pressure is a unique tool for elucidating the dynamics of integral membrane protein functions as well as for probing lipid microenvironments where they localize.

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ESR determination of membrane order parameter in yeast sterol mutants

Cited by 54 publications

References 16 publications

Yeast Genome-Wide Expression Analysis Identifies a Strong Ergosterol and Oxidative Stress Response during the Initial Stages of an Industrial Lager Fermentation

Yeast Genome-Wide Expression Analysis Identifies a Strong Ergosterol and Oxidative Stress Response during the Initial Stages of an Industrial Lager Fermentation

The Hog1 Mitogen-Activated Protein Kinase Mediates a Hypoxic Response inSaccharomyces cerevisiae

Pressure-Induced Differential Regulation of the Two Tryptophan Permeases Tat1 and Tat2 by Ubiquitin Ligase Rsp5 and Its Binding Proteins, Bul1 and Bul2

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