Improvement of fermentation ability under baking-associated stress conditions by altering the POG1 gene expression in baker's yeast.

During the bread-making process, yeast cells are exposed to many types of baking-associated stress. There is thus a demand within the baking industry for yeast strains with high fermentation abilities under these stress conditions. The POG1 gene, encoding a putative transcription factor involved in cell cycle regulation, is a multicopy suppressor of the yeast Saccharomyces cerevisiae E3 ubiquitin ligase Rsp5 mutant.

Identification of an acetate-tolerant strain of Saccharomyces cerevisiae and characterization by gene expression analysis.

A massive screening was performed to identify an acetate-tolerant strain of Saccharomyces cerevisiae. We found that S. cerevisiae ATCC 38555 is acetate-tolerant, with a fermentation profile indicating that it has a high level of acetate adaptation.

Enhancement of the proline and nitric oxide synthetic pathway improves fermentation ability under multiple baking-associated stress conditions in industrial baker's yeast.

Background: During the bread-making process, industrial baker's yeast, mostly Saccharomyces cerevisiae, is exposed to baking-associated stresses, such as air-drying and freeze-thaw stress. These baking-associated stresses exert severe injury to yeast cells, mainly due to the generation of reactive oxygen species (ROS), leading to cell death and reduced fermentation ability. Thus, there is a great need for a baker's yeast strain with higher tolerance to baking-associated stresses.

Overexpression of the transcription activator Msn2 enhances the fermentation ability of industrial baker's yeast in frozen dough.

We constructed a self-cloning diploid baker's yeast strain that overexpressed the transcription activator Msn2. It showed higher tolerance to freeze-thaw stress and higher intracellular trehalose level than observed in the wild-type strain. Overexpression of Msn2 also enhanced the fermentation ability of baker's yeast cells in frozen dough.

Simultaneous accumulation of proline and trehalose in industrial baker's yeast enhances fermentation ability in frozen dough.

Freeze tolerance is a necessary characteristic for industrial baker's yeast because frozen-dough baking is one of the key technologies for supplying oven-fresh bakery products to consumers. Both proline and trehalose are known to function as cryoprotectants in yeast cells. In order to enhance the freeze tolerance of yeast cells, we constructed a self-cloning diploid baker's yeast strain with simultaneous accumulation of proline, by expressing the PRO1-I150T allele, encoding the proline-feedback inhibition-less sensitive γ-glutamyl kinase, and trehalose, by disrupting the NTH1 gene, encoding neutral trehalase.

Proline accumulation in baker's yeast enhances high-sucrose stress tolerance and fermentation ability in sweet dough.

During bread-making processes, yeast cells are exposed to various baking-associated stresses. High-sucrose concentrations exert severe osmotic stress that seriously damages cellular components by generation of reactive oxygen species (ROS). Previously, we found that the accumulation of proline conferred freeze-thaw stress tolerance and the baker's yeast strain that accumulated proline retained higher-level fermentation abilities in frozen doughs than the wild-type strain.

Engineering of the yeast ubiquitin ligase Rsp5: isolation of a new variant that induces constitutive inactivation of the general amino acid permease Gap1.

Rsp5 is an essential ubiquitin-protein ligase in Saccharomyces cerevisiae. We found previously that the Ala401Glu rsp5 mutant is hypersensitive to various stresses that induce protein misfolding, suggesting that Rsp5 is a key enzyme for yeast cell growth under stress conditions. To isolate new Rsp5 variants as suppressors of the A401E mutant, PCR random mutagenesis was used in the rsp5(A401E) gene, and the mutagenized plasmid library was introduced into rsp5(A401E) cells.

Rsp5 is required for the nuclear export of mRNA of HSF1 and MSN2/4 under stress conditions in Saccharomyces cerevisiae.

Rsp5 is an essential and multi-functional E3 ubiquitin ligase in Saccharomyces cerevisiae. We previously isolated the Ala401Glu rsp5 mutant that is hypersensitive to various stresses. In rsp5(A401E) cells, the transcription of the stress protein genes was defective.

Overexpression of two transcriptional factors, Kin28 and Pog1, suppresses the stress sensitivity caused by the rsp5 mutation in Saccharomyces cerevisiae.

Rsp5 is an essential and multi-functional E3 ubiquitin ligase in Saccharomyces cerevisiae. The Ala401Glu rsp5 mutant, which is hypersensitive to various stresses, was isolated previously. To understand the function of Rsp5 in stress responses, suppressor genes whose overexpression allows rsp5(A401E) cells to grow at a high temperature were screened.

Rsp5 regulates expression of stress proteins via post-translational modification of Hsf1 and Msn4 in Saccharomyces cerevisiae.

Rsp5 is an essential E3 ubiquitin ligase in Saccharomyces cerevisiae and is known to ubiquitinate plasma membrane permeases followed by endocytosis and vacuolar degradation. We previously isolated the rsp5 mutant that is hypersensitive to various stresses, suggesting that Rsp5 is involved in degradation of stress-induced abnormal proteins. Here, we analyzed the ability to refold the proteins by stress proteins in the rsp5 mutant.

Functional analysis of L-serine O-acetyltransferase from Corynebacterium glutamicum.

We report here the function of L-serine O-acetyltransferase (SAT) from the glutamic acid-producing bacterium Corynebacterium glutamicum. Based on the genome sequence of C. glutamicum and the NH(2)-terminal amino-acid sequence, the gene encoding SAT (cysE) was cloned and expressed in C.