scholarly journals Membrane Fluidity of Saccharomyces cerevisiae from Huangjiu (Chinese Rice Wine) Is Variably Regulated by OLE1 To Offset the Disruptive Effect of Ethanol

2019 ◽  
Vol 85 (23) ◽  
Author(s):  
Yijin Yang ◽  
Yongjun Xia ◽  
Wuyao Hu ◽  
Leren Tao ◽  
Li Ni ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fatty Acid ◽  
Membrane Fluidity ◽  
Ethanol Tolerance ◽  
Acid Metabolism ◽  
Ethanol Stress ◽  
Disruptive Effect ◽  
Rice Wine ◽  
Chinese Rice Wine ◽  
High Ethanol

ABSTRACT An evolution and resequencing strategy was used to research the genetic basis of Saccharomyces cerevisiae BR20 (with 18 vol% ethanol tolerance) and the evolved strain F23 (with 25 vol% ethanol tolerance). Whole-genome sequencing and RNA sequencing (RNA-seq) indicated that the enhanced ethanol tolerance under 10 vol% ethanol could be attributed to amino acid metabolism, whereas 18 vol% ethanol tolerance was due to fatty acid metabolism. Ultrastructural analysis indicated that F23 exhibited better membrane integrity than did BR20 under ethanol stress. At low concentrations (<5 vol%), the partition of ethanol into the membrane increased the membrane fluidity, which had little effect on cell growth. However, the toxic effects of medium and high ethanol concentrations (5 to 20 vol%) tended to decrease the membrane fluidity. Under high ethanol stress (>10 vol%), the highly tolerant strain was able to maintain a relatively constant fluidity by increasing the content of unsaturated fatty acid (UFA), whereas less-tolerant strains show a continuous decrease in fluidity and UFA content. OLE1, which was identified as the only gene with a differential single-nucleotide polymorphism (SNP) mutation site related to fatty acid metabolism, was significantly changed in response to ethanol. The role of OLE1 in membrane fluidity was positively validated in its overexpressed transformants. Therefore, OLE1 lowered the rate of decline in membrane fluidity and thus enabled the yeast to better fight the deleterious effects of ethanol. IMPORTANCE Yeasts with superior ethanol tolerance are desirable for winemakers and wine industries. In our previous work, strain F23 was evolved with superior ethanol tolerance and fermentation activity to improve the flavor profiles of Chinese rice wine. Therefore, exploring the genomic variations and ethanol tolerance mechanism of strain F23 could contribute to an understanding of its effect on the flavor characteristics in the resulting Chinese rice wine. The cellular membrane plays a vital role in the ethanol tolerance of yeasts; however, how the membrane is regulated to fight the toxic effect of ethanol remains to be elucidated. This study suggests that the membrane fluidity is variably regulated by OLE1 to offset the disruptive effect of ethanol. Current work will help develop more ethanol-tolerant yeast strains for wine industries and contribute to a deep understanding of its high flavor-producing ability.

scholarly journals Transcriptional Regulator AcrR Increases Ethanol Tolerance through Regulation of Fatty Acid Synthesis in Lactobacillus plantarum

2019 ◽  
Vol 85 (22) ◽  
Author(s):  
Xiaopan Yang ◽  
Kunling Teng ◽  
Lili Li ◽  
Rina Su ◽  
Jie Zhang ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Membrane Fluidity ◽  
Gene Cluster ◽  
Lactobacillus Plantarum ◽  
Fatty Acid Synthesis ◽  
Binding Sites ◽  
Ethanol Tolerance ◽  
De Novo ◽  
Acid Synthesis ◽  
Ethanol Stress

ABSTRACT Lactobacillus plantarum is a versatile bacterium with significant adaptability to harsh habitats containing excessive ethanol concentrations. It was found that the L. plantarum NF92-TetR/AcrR family regulator, AcrR, significantly enhanced the growth rate of this lactic acid bacterium in the presence of ethanol. Through screening 172 ethanol-resistant related genes by electrophoretic mobility shift and quantitative reverse transcription-PCR (RT-qPCR) assays, six genes were identified to be regulated by AcrR under ethanol stress. Among these was a gene coding for a 3-hydroxyacyl-ACP dehydratase (fabZ1) regulated by AcrR under ethanol stress. AcrR regulated fabZ1 under ethanol stress by binding to its promoter, PfabZ1. DNase I footprinting analysis indicated that there were two specific AcrR binding sites on PfabZ1. RT-PCR results showed fabZ1 could cotranscribe with its downstream 12 genes and conform a fatty acid de novo biosynthesis (fab) gene cluster under the control of PfabZ1. Both RT-qPCR of the fab gene cluster in acrR knockout and overexpression strains and fatty acid methyl ester analysis of the acrR knockout strain showed that AcrR could promote fatty acid synthesis in L. plantarum NF92. Membrane fluorescence anisotropy analysis of acrR knockout and overexpression strains showed that AcrR could increase membrane fluidity under ethanol stress. Thus, AcrR could regulate fatty acid synthesis and membrane fluidity to promote the adaption of L. plantarum NF92 to a high ethanol concentration. IMPORTANCE Ethanol tolerance is essential for L. plantarum strains living in substances with more than 9% ethanol, such as wine and beer. The details regarding how L. plantarum adapts to ethanol are still lacking. This study demonstrates that AcrR regulates the de novo synthesis of fatty acids in L. plantarum adapting to toxic levels of ethanol. We also identified the ability of the TetR/AcrR family regulator to bind to the fatty acid biosynthesis gene promoter, PfabZ1, in L. plantarum and defined the binding sites. This finding facilitates the induction of the adaptation of L. plantarum strains to ethanol for food fermentation applications.

scholarly journals Auxotrophic Mutations Reduce Tolerance of Saccharomyces cerevisiae to Very High Levels of Ethanol Stress

2015 ◽  
Vol 14 (9) ◽  
pp. 884-897 ◽  
Author(s):  
Steve Swinnen ◽  
Annelies Goovaerts ◽  
Kristien Schaerlaekens ◽  
Françoise Dumortier ◽  
Pieter Verdyck ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ethanol Tolerance ◽  
Stress Factors ◽  
Causative Mutation ◽  
Ethanol Stress ◽  
Limiting Factor ◽  
Ethanol Sensitivity ◽  
Content Type ◽  
High Ethanol ◽  
Very High

ABSTRACTVery high ethanol tolerance is a distinctive trait of the yeastSaccharomyces cerevisiaewith notable ecological and industrial importance. Although many genes have been shown to be required for moderate ethanol tolerance (i.e., 6 to 12%) in laboratory strains, little is known of the much higher ethanol tolerance (i.e., 16 to 20%) in natural and industrial strains. We have analyzed the genetic basis of very high ethanol tolerance in a Brazilian bioethanol production strain by genetic mapping with laboratory strains containing artificially inserted oligonucleotide markers. The first locus contained theura3Δ0mutation of the laboratory strain as the causative mutation. Analysis of other auxotrophies also revealed significant linkage forLYS2,LEU2,HIS3, andMET15. Tolerance to only very high ethanol concentrations was reduced by auxotrophies, while the effect was reversed at lower concentrations. Evaluation of other stress conditions showed that the link with auxotrophy is dependent on the type of stress and the type of auxotrophy. When the concentration of the auxotrophic nutrient is close to that limiting growth, more stress factors can inhibit growth of an auxotrophic strain. We show that very high ethanol concentrations inhibit the uptake of leucine more than that of uracil, but the 500-fold-lower uracil uptake activity may explain the strong linkage between uracil auxotrophy and ethanol sensitivity compared to leucine auxotrophy. Since very high concentrations of ethanol inhibit the uptake of auxotrophic nutrients, the active uptake of scarce nutrients may be a major limiting factor for growth under conditions of ethanol stress.

scholarly journals Engineering the Monomer Composition of Polyhydroxyalkanoates Synthesized in Saccharomyces cerevisiae

2006 ◽  
Vol 72 (1) ◽  
pp. 536-543 ◽  
Author(s):  
Bo Zhang ◽  
Ross Carlson ◽  
Friedrich Srienc
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fatty Acid ◽  
Chain Length ◽  
Fatty Acid Metabolism ◽  
Acid Metabolism ◽  
Pha Synthase ◽  
Fatty Acid Degradation ◽  
Medium Chain ◽  
Acid Degradation ◽  
Wide Range

ABSTRACT Polyhydroxyalkanoates (PHAs) have received considerable interest as renewable-resource-based, biodegradable, and biocompatible plastics with a wide range of potential applications. We have engineered the synthesis of PHA polymers composed of monomers ranging from 4 to 14 carbon atoms in either the cytosol or the peroxisome of Saccharomyces cerevisiae by harnessing intermediates of fatty acid metabolism. Cytosolic PHA production was supported by establishing in the cytosol critical β-oxidation chemistries which are found natively in peroxisomes. This platform was utilized to supply medium-chain (C6 to C14) PHA precursors from both fatty acid degradation and synthesis to a cytosolically expressed medium-chain-length (mcl) polymerase from Pseudomonas oleovorans. Synthesis of short-chain-length PHAs (scl-PHAs) was established in the peroxisome of a wild-type yeast strain by targeting the Ralstonia eutropha scl polymerase to the peroxisome. This strain, harboring a peroxisomally targeted scl-PHA synthase, accumulated PHA up to approximately 7% of its cell dry weight. These results indicate (i) that S. cerevisiae expressing a cytosolic mcl-PHA polymerase or a peroxisomal scl-PHA synthase can use the 3-hydroxyacyl coenzyme A intermediates from fatty acid metabolism to synthesize PHAs and (ii) that fatty acid degradation is also possible in the cytosol as β-oxidation might not be confined only to the peroxisomes. Polymers of even-numbered, odd-numbered, or a combination of even- and odd-numbered monomers can be controlled by feeding the appropriate substrates. This ability should permit the rational design and synthesis of polymers with desired material properties.

Improvement of flavor profiles in Chinese rice wine by creating fermenting yeast with superior ethanol tolerance and fermentation activity

2018 ◽  
Vol 108 ◽  
pp. 83-92 ◽  
Author(s):  
Yijin Yang ◽  
Yongjun Xia ◽  
Xiangna Lin ◽  
Guangqiang Wang ◽  
Hui Zhang ◽  
...  
Keyword(s):  
Ethanol Tolerance ◽  
Rice Wine ◽  
Chinese Rice Wine

Reduction of biogenic amines production by eliminating the PEP4 gene in Saccharomyces cerevisiae during fermentation of Chinese rice wine

2015 ◽  
Vol 178 ◽  
pp. 208-211 ◽  
Author(s):  
Xuewu Guo ◽  
Xiangyu Guan ◽  
Yazhou Wang ◽  
Lina Li ◽  
Deguang Wu ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Biogenic Amines ◽  
Rice Wine ◽  
Chinese Rice Wine ◽  
Pep4 Gene

scholarly journals Mitochondrial Superoxide Dismutase and Yap1p Act as a Signaling Module Contributing to Ethanol Tolerance of the Yeast Saccharomyces cerevisiae

2016 ◽  
Vol 83 (3) ◽  
Author(s):  
Anna N. Zyrina ◽  
Ekaterina A. Smirnova ◽  
Olga V. Markova ◽  
Fedor F. Severin ◽  
Dmitry A. Knorre
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Ethanol Tolerance ◽  
Yeast Cells ◽  
Ethanol Stress ◽  
Mitochondrial Enzymes ◽  
Mitochondrial Superoxide ◽  
Mitochondrial Superoxide Dismutase

ABSTRACT There are two superoxide dismutases in the yeast Saccharomyces cerevisiae—cytoplasmic and mitochondrial enzymes. Inactivation of the cytoplasmic enzyme, Sod1p, renders the cells sensitive to a variety of stresses, while inactivation of the mitochondrial isoform, Sod2p, typically has a weaker effect. One exception is ethanol-induced stress. Here we studied the role of Sod2p in ethanol tolerance of yeast. First, we found that repression of SOD2 prevents ethanol-induced relocalization of yeast hydrogen peroxide-sensing transcription factor Yap1p, one of the key stress resistance proteins. In agreement with this, the levels of Trx2p and Gsh1p, proteins encoded by Yap1 target genes, were decreased in the absence of Sod2p. Analysis of the ethanol sensitivities of the cells lacking Sod2p, Yap1p, or both indicated that the two proteins act in the same pathway. Moreover, preconditioning with hydrogen peroxide restored the ethanol resistance of yeast cells with repressed SOD2. Interestingly, we found that mitochondrion-to-nucleus signaling by Rtg proteins antagonizes Yap1p activation. Together, our data suggest that hydrogen peroxide produced by Sod2p activates Yap1p and thus plays a signaling role in ethanol tolerance. IMPORTANCE Baker's yeast harbors multiple systems that ensure tolerance to high concentrations of ethanol. Still, the role of mitochondria under severe ethanol stress in yeast is not completely clear. Our study revealed a signaling function of mitochondria which contributes significantly to the ethanol tolerance of yeast cells. We found that mitochondrial superoxide dismutase Sod2p and cytoplasmic hydrogen peroxide sensor Yap1p act together as a module of the mitochondrion-to-nucleus signaling pathway. We also report cross talk between this pathway and the conventional retrograde signaling cascade activated by dysfunctional mitochondria.

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