scholarly journals Effect of HXT1 and HXT7 hexose transporter overexpression on wild-type and lactic acid producing Saccharomyces cerevisiae cells

2010 ◽  
Vol 9 (1) ◽  
pp. 15 ◽  
Author(s):  
Giorgia Rossi ◽  
Michael Sauer ◽  
Danilo Porro ◽  
Paola Branduardi
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Lactic Acid ◽  
Hexose Transporter ◽  
Wild Type

scholarly journals Hxt-Carrier-Mediated Glucose Efflux upon Exposure of Saccharomyces cerevisiae to Excess Maltose

2002 ◽  
Vol 68 (9) ◽  
pp. 4259-4265 ◽  
Author(s):  
Mickel L. A. Jansen ◽  
Johannes H. De Winde ◽  
Jack T. Pronk
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Reference Strain ◽  
External Medium ◽  
Hexose Transport ◽  
Hexose Transporter ◽  
Wild Type ◽  
Experimental Proof ◽  
Chemostat Cultures ◽  
Selection Of ◽  
Intracellular Glucose

ABSTRACT When wild-type Saccharomyces cerevisiae strains pregrown in maltose-limited chemostat cultures were exposed to excess maltose, release of glucose into the external medium was observed. Control experiments confirmed that glucose release was not caused by cell lysis or extracellular maltose hydrolysis. To test the hypothesis that glucose efflux involved plasma membrane glucose transporters, experiments were performed with an S. cerevisiae strain in which all members of the hexose transporter (HXT) gene family had been eliminated and with an isogenic reference strain. Glucose efflux was virtually eliminated in the hexose-transport-deficient strain. This constitutes experimental proof that Hxt transporters facilitate export of glucose from S. cerevisiae cells. After exposure of the hexose-transport-deficient strain to excess maltose, an increase in the intracellular glucose level was observed, while the concentrations of glucose 6-phosphate and ATP remained relatively low. These results demonstrate that glucose efflux can occur as a result of uncoordinated expression of the initial steps of maltose metabolism and the subsequent reactions in glucose dissimilation. This is a relevant phenomenon for selection of maltose-constitutive strains for baking and brewing.

Regulation of basal and induced levels of the MEL1 transcript in Saccharomyces cerevisiae

1984 ◽  
Vol 4 (7) ◽  
pp. 1238-1245
Author(s):  
M A Post-Beittenmiller ◽  
R W Hamilton ◽  
J E Hopper
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Lactic Acid ◽  
Carbon Sources ◽  
Regulatory Proteins ◽  
Northern Hybridization ◽  
Transcriptional Expression ◽  
Wild Type ◽  
Naturally Occurring ◽  
Alpha Galactosidase ◽  
In Cells

The MEL1 gene in Saccharomyces cerevisiae is required for the production of alpha-galactosidase and for the catabolism of melibiose. Production of alpha-galactosidase is induced by galactose or melibiose and repressed by glucose. Inducibility is controlled by the positive and negative regulatory proteins GAL4 and GAL80, respectively. We have cloned the MEL1 gene to study its transcriptional expression and regulation. Evidence is presented that the MEL1 gene encodes alpha-galactosidase and that mel0 is a naturally occurring allele which lacks the alpha-galactosidase-coding sequences. RNAs prepared from wild-type cells and from cells carrying either the noninducible gal4-2 or GAL80S-100 allele grown on three different carbon sources were examined by Northern hybridization analyses. In wild-type cells under noninducing conditions, such as growth on glycerol-lactic acid, the MEL1 transcript was detected at a basal level which was 1 to 2% of the fully induced level. The basal level of expression was diminished in cells carrying the gal4-2 mutant allele but not in cells carrying the GAL80S-100 allele. The basal and induced RNA levels are repressed by glucose. Size determinations of the MEL1 transcripts detected in glycerol-lactic acid- and galactose-grown cells provided no evidence for two distinct transcripts.

Caractéristiques d'un mutant homothallique de Saccharomyces cerevisiae Hansen

1971 ◽  
Vol 17 (3) ◽  
pp. 425-428
Author(s):  
A. Arnaud ◽  
Françoise Vezinhet ◽  
P. Galzy
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Lactic Acid ◽  
Vegetative Growth ◽  
Nitrous Acid ◽  
Solid Medium ◽  
Wild Strain ◽  
Wild Type

Through mutagenesis by nitrous acid a mutant was obtained which differed from the wild strain by two independent characters. The mutant gave smooth colonies on a solid medium containing lactic acid; the wild type yielded rough colonies on the same medium. The smooth colony character was unstable during vegetative growth. The mutant was homothallic. This character was stable during vegetative growth but it was not segregated through meïosis. This mutation inducing homothallism is not controlled by a gene.

scholarly journals Regulation of basal and induced levels of the MEL1 transcript in Saccharomyces cerevisiae.

1984 ◽  
Vol 4 (7) ◽  
pp. 1238-1245 ◽  
Author(s):  
M A Post-Beittenmiller ◽  
R W Hamilton ◽  
J E Hopper
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Lactic Acid ◽  
Carbon Sources ◽  
Regulatory Proteins ◽  
Northern Hybridization ◽  
Transcriptional Expression ◽  
Wild Type ◽  
Naturally Occurring ◽  
Alpha Galactosidase ◽  
In Cells

The MEL1 gene in Saccharomyces cerevisiae is required for the production of alpha-galactosidase and for the catabolism of melibiose. Production of alpha-galactosidase is induced by galactose or melibiose and repressed by glucose. Inducibility is controlled by the positive and negative regulatory proteins GAL4 and GAL80, respectively. We have cloned the MEL1 gene to study its transcriptional expression and regulation. Evidence is presented that the MEL1 gene encodes alpha-galactosidase and that mel0 is a naturally occurring allele which lacks the alpha-galactosidase-coding sequences. RNAs prepared from wild-type cells and from cells carrying either the noninducible gal4-2 or GAL80S-100 allele grown on three different carbon sources were examined by Northern hybridization analyses. In wild-type cells under noninducing conditions, such as growth on glycerol-lactic acid, the MEL1 transcript was detected at a basal level which was 1 to 2% of the fully induced level. The basal level of expression was diminished in cells carrying the gal4-2 mutant allele but not in cells carrying the GAL80S-100 allele. The basal and induced RNA levels are repressed by glucose. Size determinations of the MEL1 transcripts detected in glycerol-lactic acid- and galactose-grown cells provided no evidence for two distinct transcripts.

scholarly journals Functional expression, quantification and cellular localization of the Hxt2 hexose transporter of Saccharomyces cerevisiae tagged with the green fluorescent protein

1999 ◽  
Vol 339 (2) ◽  
pp. 299-307 ◽  
Author(s):  
Arthur L. KRUCKEBERG ◽  
Ling YE ◽  
Jan A. BERDEN ◽  
Karel van DAM
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Plasma Membrane ◽  
Green Fluorescent Protein ◽  
Glucose Transport ◽  
Cellular Localization ◽  
Fluorescent Protein ◽  
Hexose Transporter ◽  
High Concentrations ◽  
Green Fluorescent

The Hxt2 glucose transport protein of Saccharomyces cerevisiae was genetically fused at its C-terminus with the green fluorescent protein (GFP). The Hxt2-GFP fusion protein is a functional hexose transporter: it restored growth on glucose to a strain bearing null mutations in the hexose transporter genes GAL2 and HXT1 to HXT7. Furthermore, its glucose transport activity in this null strain was not markedly different from that of the wild-type Hxt2 protein. We calculated from the fluorescence level and transport kinetics that induced cells had 1.4×105 Hxt2-GFP molecules per cell, and that the catalytic-centre activity of the Hxt2-GFP molecule in vivo is 53 s-1 at 30 °C. Expression of Hxt2-GFP was induced by growth at low concentrations of glucose. Under inducing conditions the Hxt2-GFP fluorescence was localized to the plasma membrane. In a strain impaired in the fusion of secretory vesicles with the plasma membrane, the fluorescence accumulated in the cytoplasm. When induced cells were treated with high concentrations of glucose, the fluorescence was redistributed to the vacuole within 4 h. When endocytosis was genetically blocked, the fluorescence remained in the plasma membrane after treatment with high concentrations of glucose.

scholarly journals Effects of Mutations of RAD50, RAD51, RAD52, and Related Genes on Illegitimate Recombination in Saccharomyces cerevisiae

Genetics ◽  
1996 ◽  
Vol 142 (2) ◽  
pp. 383-391 ◽  
Author(s):  
Yasumasa Tsukamoto ◽  
Jun-ichi Kato ◽  
Hideo Ikeda
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Quantitative Analysis ◽  
Structural Analysis ◽  
Recombination Rate ◽  
Type Strain ◽  
Negative Selection ◽  
Wild Type Strain ◽  
Illegitimate Recombination ◽  
Wild Type ◽  
In The Wild

Abstract To examine the mechanism of illegitimate recombination in Saccharomyces cerevisiae, we have developed a plasmid system for quantitative analysis of deletion formation. A can1 cyh2 cell carrying two negative selection markers, the CAN1 and CYH2 genes, on a YCp plasmid is sensitive to canavanine and cycloheximide, but the cell becomes resistant to both drugs when the plasmid has a deletion over the CAN1 and CYH2 genes. Structural analysis of the recombinant plasmids obtained from the resistant cells showed that the plasmids had deletions at various sites of the CAN1-CYH2 region and there were only short regions of homology (1-5 bp) at the recombination junctions. The results indicated that the deletion detected in this system were formed by illegitimate recombination. Study on the effect of several rad mutations showed that the recombination rate was reduced by 30-, 10-, 10-, and 10-fold in the rad52, rad50, mre11, and xrs2 mutants, respectively, while in the rud51, 54, 55, and 57 mutants, the rate was comparable to that in the wild-type strain. The rad52 mutation did not affect length of homology at junction sites of illegitimate recombination.

scholarly journals Saccharomyces cerevisiae Fermentation of 28 Barley and 12 Oat Cultivars

Fermentation ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 59
Author(s):  
Timothy J. Tse ◽  
Daniel J. Wiens ◽  
Jianheng Shen ◽  
Aaron D. Beattie ◽  
Martin J. T. Reaney
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Acetic Acid ◽  
Lactic Acid ◽  
Succinic Acid ◽  
Alcoholic Fermentation ◽  
Ethanol Yield ◽  
Cereal Crops ◽  
Fermentation Products ◽  
Barley Cultivars ◽  
Oat Cultivars

As barley and oat production have recently increased in Canada, it has become prudent to investigate these cereal crops as potential feedstocks for alcoholic fermentation. Ethanol and other coproduct yields can vary substantially among fermented feedstocks, which currently consist primarily of wheat and corn. In this study, the liquified mash of milled grains from 28 barley (hulled and hull-less) and 12 oat cultivars were fermented with Saccharomyces cerevisiae to determine concentrations of fermentation products (ethanol, isopropanol, acetic acid, lactic acid, succinic acid, α-glycerylphosphorylcholine (α-GPC), and glycerol). On average, the fermentation of barley produced significantly higher amounts of ethanol, isopropanol, acetic acid, succinic acid, α-GPC, and glycerol than that of oats. The best performing barley cultivars were able to produce up to 78.48 g/L (CDC Clear) ethanol and 1.81 g/L α-GPC (CDC Cowboy). Furthermore, the presence of milled hulls did not impact ethanol yield amongst barley cultivars. Due to its superior ethanol yield compared to oats, barley is a suitable feedstock for ethanol production. In addition, the accumulation of α-GPC could add considerable value to the fermentation of these cereal crops.

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