scholarly journals Nutrient Signaling via the TORC1-Greatwall-PP2AB55δ Pathway Is Responsible for the High Initial Rates of Alcoholic Fermentation in Sake Yeast Strains of Saccharomyces cerevisiae

2018 ◽  
Vol 85 (1) ◽  
Author(s):  
Daisuke Watanabe ◽  
Takuma Kajihara ◽  
Yukiko Sugimoto ◽  
Kenichi Takagi ◽  
Megumi Mizuno ◽  
...  

ABSTRACT Saccharomyces cerevisiae sake yeast strain Kyokai no. 7 (K7) and its relatives carry a homozygous loss-of-function mutation in the RIM15 gene, which encodes a Greatwall family protein kinase. Disruption of RIM15 in nonsake yeast strains leads to improved alcoholic fermentation, indicating that the defect in Rim15p is associated with the enhanced fermentation performance of sake yeast cells. In order to understand how Rim15p mediates fermentation control, we here focused on target-of-rapamycin protein kinase complex 1 (TORC1) and protein phosphatase 2A with the B55δ regulatory subunit (PP2AB55δ), complexes that are known to act upstream and downstream of Rim15p, respectively. Several lines of evidence, including our previous transcriptomic analysis data, suggested enhanced TORC1 signaling in sake yeast cells during sake fermentation. Fermentation tests of the TORC1-related mutants using a laboratory strain revealed that TORC1 signaling positively regulates the initial fermentation rate in a Rim15p-dependent manner. Deletion of the CDC55 gene, encoding B55δ, abolished the high fermentation performance of Rim15p-deficient laboratory yeast and sake yeast cells, indicating that PP2AB55δ mediates the fermentation control by TORC1 and Rim15p. The TORC1-Greatwall-PP2AB55δ pathway similarly affected the fermentation rate in the fission yeast Schizosaccharomyces pombe, strongly suggesting that the evolutionarily conserved pathway governs alcoholic fermentation in yeasts. It is likely that elevated PP2AB55δ activity accounts for the high fermentation performance of sake yeast cells. Heterozygous loss-of-function mutations in CDC55 found in K7-related sake strains may indicate that the Rim15p-deficient phenotypes are disadvantageous to cell survival. IMPORTANCE The biochemical processes and enzymes responsible for glycolysis and alcoholic fermentation by the yeast S. cerevisiae have long been the subject of scientific research. Nevertheless, the factors determining fermentation performance in vivo are not fully understood. As a result, the industrial breeding of yeast strains has required empirical characterization of fermentation by screening numerous mutants through laborious fermentation tests. To establish a rational and efficient breeding strategy, key regulators of alcoholic fermentation need to be identified. In the present study, we focused on how sake yeast strains of S. cerevisiae have acquired high alcoholic fermentation performance. Our findings provide a rational molecular basis to design yeast strains with optimal fermentation performance for production of alcoholic beverages and bioethanol. In addition, as the evolutionarily conserved TORC1-Greatwall-PP2AB55δ pathway plays a major role in the glycolytic control, our work may contribute to research on carbohydrate metabolism in higher eukaryotes.

2018 ◽  
Author(s):  
Daisuke Watanabe ◽  
Takuma Kajihara ◽  
Yukiko Sugimoto ◽  
Kenichi Takagi ◽  
Megumi Mizuno ◽  
...  

ABSTRACTSake yeast strain Kyokai no. 7 (K7) and its Saccharomyces cerevisiae relatives carry a homozygous loss-of-function mutation in the RIM15 gene, which encodes a Greatwall-family protein kinase. Disruption of RIM15 in non-sake yeast strains leads to improved alcoholic fermentation, indicating that the defect in Rim15p is associated with the enhanced fermentation performance of sake yeast cells. In order to understand how Rim15p mediates fermentation control, we here focused on target-of-rapamycin protein kinase complex 1 (TORC1) and protein phosphatase 2A with the B55Δ regulatory subunit (PP2AB55δ), complexes that are known to act upstream and downstream of Rim15p, respectively. Several lines of evidence, including our previous transcriptomic analysis data, suggested enhanced TORC1 signaling in sake yeast cells during sake fermentation. Fermentation tests of the TORC1-related mutants using a laboratory strain revealed that TORC1 signaling positively regulates the initial fermentation rate in a Rim15p-dependent manner. Deletion of the CDC55 gene encoding B55δ abolished the high fermentation performance of Rim15p-deficient laboratory yeast and sake yeast cells, indicating that PP2AB55δ mediates the fermentation control by TORC1 and Rim15p. The TORC1-Greatwall-PP2AB55δ pathway similarly affected the fermentation rate in the fission yeast Schizosaccharomyces pombe, strongly suggested that the evolutionarily conserved pathway governs alcoholic fermentation in yeasts. It is likely that elevated PP2AB55δ activity accounts for the high fermentation performance of sake yeast cells. Heterozygous loss-of-function mutations in CDC55 found in K7-related sake strains may indicate that the Rim15p-deficient phenotypes are disadvantageous to cell survival.IMPORTANCEThe biochemical processes and enzymes responsible for glycolysis and alcoholic fermentation by the yeast S. cerevisiae have long been the subject of scientific research. Nevertheless, the factors determining fermentation performance in vivo are not fully understood. As a result, the industrial breeding of yeast strains has required empirical characterization of fermentation by screening numerous mutants through laborious fermentation tests. To establish a rational and efficient breeding strategy, key regulators of alcoholic fermentation need to be identified. In the present study, we focused on how sake yeast strains of S. cerevisiae have acquired high alcoholic fermentation performance. Our findings provide a rational molecular basis to design yeast strains with optimal fermentation performance for production of alcoholic beverages and bioethanol. In addition, as the evolutionarily conserved TORC1-Greatwall-PP2AB55δ pathway plays a major role in the glycolytic control, our work may contribute to research on carbohydrate metabolism in higher eukaryotes.


2015 ◽  
Vol 82 (1) ◽  
pp. 340-351 ◽  
Author(s):  
Daisuke Watanabe ◽  
Yan Zhou ◽  
Aiko Hirata ◽  
Yukiko Sugimoto ◽  
Kenichi Takagi ◽  
...  

ABSTRACTThe high fermentation rate ofSaccharomyces cerevisiaesake yeast strains is attributable to a loss-of-function mutation in theRIM15gene, which encodes a Greatwall-family protein kinase that is conserved among eukaryotes. In the present study, we performed intracellular metabolic profiling analysis and revealed that deletion of theRIM15gene in a laboratory strain impaired glucose-anabolic pathways through the synthesis of UDP-glucose (UDPG). Although Rim15p is required for the synthesis of trehalose and glycogen from UDPG upon entry of cells into the quiescent state, we found that Rim15p is also essential for the accumulation of cell wall β-glucans, which are also anabolic products of UDPG. Furthermore, the impairment of UDPG or 1,3-β-glucan synthesis contributed to an increase in the fermentation rate. Transcriptional induction ofPGM2(phosphoglucomutase) andUGP1(UDPG pyrophosphorylase) was impaired in Rim15p-deficient cells in the early stage of fermentation. These findings demonstrate that the decreased anabolism of glucose into UDPG and 1,3-β-glucan triggered by a defect in the Rim15p-mediated upregulation ofPGM2andUGP1redirects the glucose flux into glycolysis. Consistent with this, sake yeast strains with defective Rim15p exhibited impaired expression ofPGM2andUGP1and decreased levels of β-glucans, trehalose, and glycogen during sake fermentation. We also identified a sake yeast-specific mutation in the glycogen synthesis-associated glycogenin geneGLG2, supporting the conclusion that the glucose-anabolic pathway is impaired in sake yeast. These findings demonstrate that downregulation of the UDPG synthesis pathway is a key mechanism accelerating alcoholic fermentation in industrially utilizedS. cerevisiaesake strains.


2012 ◽  
Vol 78 (11) ◽  
pp. 4008-4016 ◽  
Author(s):  
Daisuke Watanabe ◽  
Yuya Araki ◽  
Yan Zhou ◽  
Naoki Maeya ◽  
Takeshi Akao ◽  
...  

ABSTRACTSake yeast cells have defective entry into the quiescent state, allowing them to sustain high fermentation rates. To reveal the underlying mechanism, we investigated the PAS kinase Rim15p, which orchestrates initiation of the quiescence program inSaccharomyces cerevisiae. We found that Rim15p is truncated at the carboxyl terminus in modern sake yeast strains as a result of a frameshift mutation. Introduction of this mutation or deletion of the full-lengthRIM15gene in a laboratory strain led to a defective stress response, decreased synthesis of the storage carbohydrates trehalose and glycogen, and impaired G1arrest, which together closely resemble the characteristic phenotypes of sake yeast. Notably, expression of a functionalRIM15gene in a modern sake strain suppressed all of these phenotypes, demonstrating that dysfunction of Rim15p prevents sake yeast cells from entering quiescence. Moreover, loss of Rim15p or its downstream targets Igo1p and Igo2p remarkably improved the fermentation rate in a laboratory strain. This finding verified that Rim15p-mediated entry into quiescence plays pivotal roles in the inhibition of ethanol fermentation. Taken together, our results suggest that the loss-of-function mutation in theRIM15gene may be the key genetic determinant of the increased ethanol production rates in modern sake yeast strains.


2016 ◽  
Vol 82 (6) ◽  
pp. 1906-1916 ◽  
Author(s):  
Carlos Andrés Martínez-Garay ◽  
Rosa de Llanos ◽  
Antonia María Romero ◽  
María Teresa Martínez-Pastor ◽  
Sergi Puig

ABSTRACTIron is an essential micronutrient for all eukaryotic organisms. However, the low solubility of ferric iron has tremendously increased the prevalence of iron deficiency anemia, especially in women and children, with dramatic consequences. Baker's yeastSaccharomyces cerevisiaeis used as a model eukaryotic organism, a fermentative microorganism, and a feed supplement. In this report, we explore the genetic diversity of 123 wild and domestic strains ofS. cerevisiaeisolated from different geographical origins and sources to characterize how yeast cells respond to elevated iron concentrations in the environment. By using two different forms of iron, we selected and characterized both iron-sensitive and iron-resistant yeast strains. We observed that when the iron concentration in the medium increases, iron-sensitive strains accumulate iron more rapidly than iron-resistant isolates. We observed that, consistent with excess iron leading to oxidative stress, the redox state of iron-sensitive strains was more oxidized than that of iron-resistant strains. Growth assays in the presence of different oxidative reagents ruled out that this phenotype was due to alterations in the general oxidative stress protection machinery. It was noteworthy that iron-resistant strains were more sensitive to iron deficiency conditions than iron-sensitive strains, which suggests that adaptation to either high or low iron is detrimental for the opposite condition. An initial gene expression analysis suggested that alterations in iron homeostasis genes could contribute to the different responses of distant iron-sensitive and iron-resistant yeast strains to elevated environmental iron levels.


Beverages ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 27
Author(s):  
Dimitrios Kontogiannatos ◽  
Vicky Troianou ◽  
Maria Dimopoulou ◽  
Polydefkis Hatzopoulos ◽  
Yorgos Kotseridis

Nemea and Mantinia are famous wine regions in Greece known for two indigenous grape varieties, Agiorgitiko and Moschofilero, which produce high quality PDO wines. In the present study, indigenous Saccharomyces cerevisiae yeast strains were isolated and identified from spontaneous alcoholic fermentation of Agiorgitiko and Moschofilero musts in order to evaluate their oenological potential. Random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) recovered the presence of five distinct profiles from a total of 430 yeast isolates. The five obtained strains were evaluated at microvinifications trials and tested for basic oenological and biochemical parameters including sulphur dioxide and ethanol tolerance as well as H2S production in sterile grape must. The selected autochthonous yeast strains named, Soi2 (Agiorgitiko wine) and L2M (Moschofilero wine), were evaluated also in industrial (4000L) fermentations to assess their sensorial and oenological characteristics. The volatile compounds of the produced wines were determined by GC-FID. Our results demonstrated the feasibility of using Soi2 and L2M strains in industrial fermentations for Agiorgitiko and Moschofilero grape musts, respectively.


1993 ◽  
Vol 13 (5) ◽  
pp. 3076-3083
Author(s):  
K Irie ◽  
M Takase ◽  
K S Lee ◽  
D E Levin ◽  
H Araki ◽  
...  

The PKC1 gene of Saccharomyces cerevisiae encodes a homolog of mammalian protein kinase C that is required for normal growth and division of yeast cells. We report here the isolation of the yeast MKK1 and MKK2 (for mitogen-activated protein [MAP] kinase-kinase) genes which, when overexpressed, suppress the cell lysis defect of a temperature-sensitive pkc1 mutant. The MKK genes encode protein kinases most similar to the STE7 product of S. cerevisiae, the byr1 product of Schizosaccharomyces pombe, and vertebrate MAP kinase-kinases. Deletion of either MKK gene alone did not cause any apparent phenotypic defects, but deletion of both MKK1 and MKK2 resulted in a temperature-sensitive cell lysis defect that was suppressed by osmotic stabilizers. This phenotypic defect is similar to that associated with deletion of the BCK1 gene, which is thought to function in the pathway mediated by PCK1. The BCK1 gene also encodes a predicted protein kinase. Overexpression of MKK1 suppressed the growth defect caused by deletion of BCK1, whereas an activated allele of BCK1 (BCK1-20) did not suppress the defect of the mkk1 mkk2 double disruption. Furthermore, overexpression of MPK1, which encodes a protein kinase closely related to vertebrate MAP kinases, suppressed the defect of the mkk1 mkk2 double mutant. These results suggest that MKK1 and MKK2 function in a signal transduction pathway involving the protein kinases encoded by PKC1, BCK1, and MPK1. Genetic epistasis experiments indicated that the site of action for MKK1 and MKK2 is between BCK1 and MPK1.


Fermentation ◽  
2018 ◽  
Vol 4 (3) ◽  
pp. 59 ◽  
Author(s):  
Tingting Liu ◽  
Shuangcheng Huang ◽  
Anli Geng

Cost-effective production of cellulosic ethanol requires robust microorganisms for rapid co-fermentation of glucose and xylose. This study aims to develop a recombinant diploid xylose-fermenting Saccharomyces cerevisiae strain for efficient conversion of lignocellulosic biomass sugars to ethanol. Episomal plasmids harboring codon-optimized Piromyces sp. E2 xylose isomerase (PirXylA) and Orpinomyces sp. ukk1 xylose (OrpXylA) genes were constructed and transformed into S. cerevisiae. The strain harboring plasmids with tandem PirXylA was favorable for xylose utilization when xylose was used as the sole carbon source, while the strain harboring plasmids with tandem OrpXylA was beneficial for glucose and xylose cofermentation. PirXylA and OrpXylA genes were also individually integrated into the genome of yeast strains in multiple copies. Such integration was beneficial for xylose alcoholic fermentation. The respiration-deficient strain carrying episomal or integrated OrpXylA genes exhibited the best performance for glucose and xylose co-fermentation. This was partly attributed to the high expression levels and activities of xylose isomerase. Mating a respiration-efficient strain carrying the integrated PirXylA gene with a respiration-deficient strain harboring integrated OrpXylA generated a diploid recombinant xylose-fermenting yeast strain STXQ with enhanced cell growth and xylose fermentation. Co-fermentation of 162 g L−1 glucose and 95 g L−1 xylose generated 120.6 g L−1 ethanol in 23 h, with sugar conversion higher than 99%, ethanol yield of 0.47 g g−1, and ethanol productivity of 5.26 g L−1·h−1.


1995 ◽  
Vol 15 (7) ◽  
pp. 3487-3495 ◽  
Author(s):  
M P Draper ◽  
C Salvadore ◽  
C L Denis

The CCR4 protein from Saccharomyces cerevisiae is a component of a multisubunit complex that is required for the regulation of a number of genes in yeast cells. We report here the identification of a mouse protein (mCAF1 [mouse CCR4-associated factor 1]) which is capable of interacting with and binding to the yeast CCR4 protein. The mCAF1 protein was shown to have significant similarity to proteins from humans, Caenorhabditis elegans, Arabidopsis thaliana, and S. cerevisiae. The yeast gene (yCAF1) had been previously cloned as the POP2 gene, which is required for expression of several genes. Both yCAF1 (POP2) and the C. elegans homolog of CAF1 were shown to genetically interact with CCR4 in vivo, and yCAF1 (POP2) physically associated with CCR4. Disruption of the CAF1 (POP2) gene in yeast cells gave phenotypes and defects in transcription similar to those observed with disruptions of CCR4, including the ability to suppress spt10-enhanced ADH2 expression. In addition, yCAF1 (POP2) when fused to LexA was capable of activating transcription. mCAF1 could also activate transcription when fused to LexA and could functionally substitute for yCAF1 in allowing ADH2 expression in an spt10 mutant background. These data imply that CAF1 is a component of the CCR4 protein complex and that this complex has retained evolutionarily conserved functions important to eukaryotic transcription.


2001 ◽  
Vol 21 (1) ◽  
pp. 175-184 ◽  
Author(s):  
Omri Erez ◽  
Chaim Kahana

ABSTRACT Although most cells are capable of transporting polyamines, the mechanism that regulates polyamine transport in eukaryotes is still largely unknown. Using a genetic screen for clones capable of restoring spermine sensitivity to spermine-tolerant mutants ofSaccharomyces cerevisiae, we have demonstrated that Sky1p, a recently identified SR protein kinase, is a key regulator of polyamine transport. Yeast cells deleted for SKY1 developed tolerance to toxic levels of spermine, while overexpression of Sky1p in wild-type cells increased their sensitivity to spermine. Expression of the wild-type Sky1p but not of a catalytically inactive mutant restored sensitivity to spermine. SKY1 disruption results in dramatically reduced uptake of spermine, spermidine, and putrescine. In addition to spermine tolerance, sky1Δ cells exhibit increased tolerance to lithium and sodium ions but somewhat increased sensitivity to osmotic shock. The observed halotolerance suggests potential regulatory interaction between the transport of polyamines and inorganic ions, as suggested in the case of the Ptk2p, a recently described regulator of polyamine transport. We demonstrate that these two kinases act in two different signaling pathways. While deletion or overexpression of SKY1 did not significantly affect Pma1p activity, the ability of overexpressed Sky1p, Ptk1p, and Ptk2p to increase sensitivity to LiCl depends on the integrity ofPPZ1 but not of ENA1.


2017 ◽  
Vol 83 (20) ◽  
Author(s):  
Bruna Inez Carvalho Figueiredo ◽  
Margarete Alice Fontes Saraiva ◽  
Paloma Patrick de Souza Pimenta ◽  
Miriam Conceição de Souza Testasicca ◽  
Geraldo Magela Santos Sampaio ◽  
...  

ABSTRACT The development of hybrids has been an effective approach to generate novel yeast strains with optimal technological profile for use in beer production. This study describes the generation of a new yeast strain for lager beer production by direct mating between two Saccharomyces cerevisiae strains isolated from cachaça distilleries: one that was strongly flocculent, and the other with higher production of acetate esters. The first step in this procedure was to analyze the sporulation ability and reproductive cycle of strains belonging to a specific collection of yeasts isolated from cachaça fermentation vats. Most strains showed high rates of sporulation, spore viability, and homothallic behavior. In order to obtain new yeast strains with desirable properties useful for lager beer production, we compare haploid-to-haploid and diploid-to-diploid mating procedures. Moreover, an assessment of parental phenotype traits showed that the segregant diploid C2-1d generated from a diploid-to-diploid mating experiment showed good fermentation performance at low temperature, high flocculation capacity, and desirable production of acetate esters that was significantly better than that of one type lager strain. Therefore, strain C2-1d might be an important candidate for the production of lager beer, with distinct fruit traces and originating using a non-genetically modified organism (GMO) approach. IMPORTANCE Recent work has suggested the utilization of hybridization techniques for the generation of novel non-genetically modified brewing yeast strains with combined properties not commonly found in a unique yeast strain. We have observed remarkable traits, especially low temperature tolerance, maltotriose utilization, flocculation ability, and production of volatile aroma compounds, among a collection of Saccharomyces cerevisiae strains isolated from cachaça distilleries, which allow their utilization in the production of beer. The significance of our research is in the use of breeding/hybridization techniques to generate yeast strains that would be appropriate for producing new lager beers by exploring the capacity of cachaça yeast strains to flocculate and to ferment maltose at low temperature, with the concomitant production of flavoring compounds.


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