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Reprogramming of the Ethanol Stress Response in Saccharomyces cerevisiae by the Transcription Factor Znf1 and Its Effect on the Biosynthesis of Glycerol and Ethanol.
Appl Environ Microbiol. 2021 07 27; 87(16):e0058821.AE

Abstract

High ethanol levels can severely inhibit the growth of yeast cells and fermentation productivity. The ethanologenic yeast Saccharomyces cerevisiae activates several well-defined cellular mechanisms of ethanol stress response (ESR); however, the involved regulatory control remains to be characterized. Here, we report a new transcription factor of ethanol stress adaptation called Znf1. It plays a central role in ESR by activating genes for glycerol and fatty acid production (GUP1, GPP1, GPP2, GPD1, GAT1, and OLE1) to preserve plasma membrane integrity. Importantly, Znf1 also activates genes implicated in cell wall biosynthesis (FKS1, SED1, and SMI1) and in the unfolded protein response (HSP30, HSP104, KAR1, and LHS1) to protect cells from proteotoxic stress. The znf1Δ strain displays increased sensitivity to ethanol, the endoplasmic reticulum (ER) stressor β-mercaptoethanol, and the cell wall-perturbing agent calcofluor white. To compensate for a defective cell wall, the strain lacking ZNF1 or its target SMI1 displays increased glycerol levels of 19.6% and 27.7%, respectively. Znf1 collectively regulates an intricate network of target genes essential for growth, protein refolding, and production of key metabolites. Overexpression of ZNF1 not only confers tolerance to high ethanol levels but also increases ethanol production by 4.6% (8.43 g/liter) or 2.8% (75.78 g/liter) when 2% or 20% (wt/vol) glucose, respectively, is used as a substrate, compared to that of the wild-type strain. The mutually stress-responsive transcription factors Msn2/4, Hsf1, and Yap1 are associated with some promoters of Znf1's target genes to promote ethanol stress tolerance. In conclusion, this work implicates the novel regulator Znf1 in coordinating expression of ESR genes and illuminates the unifying transcriptional reprogramming during alcoholic fermentation. IMPORTANCE The yeast S. cerevisiae is a major microbe that is widely used in food and nonfood industries. However, accumulation of ethanol has a negative effect on its growth and limits ethanol production. The Znf1 transcription factor has been implicated as a key regulator of glycolysis and gluconeogenesis in the utilization of different carbon sources, including glucose, the most abundant sugar on earth, and nonfermentable substrates. Here, the role of Znf1 in ethanol stress response is defined. Znf1 actively reprograms expression of genes linked to the unfolded protein response (UPR), heat shock response, glycerol and carbohydrate metabolism, and biosynthesis of cell membrane and cell wall components. A complex interplay among transcription factors of ESR indicates transcriptional fine-tuning as the main mechanism of stress adaptation, and Znf1 plays a major regulatory role in the coordination. Understanding the adaptive ethanol stress mechanism is crucial to engineering robust yeast strains for enhanced stress tolerance or increased ethanol production.

Authors+Show Affiliations

King Mongkut's University of Technology Thonburi, Division of Biochemical Technology, School of Bioresources and Technology, Bangkok, Thailand.King Mongkut's University of Technology Thonburi, Division of Biochemical Technology, School of Bioresources and Technology, Bangkok, Thailand. Pilot Plant Development and Training Institute, King Mongkut's University of Technology Thonburi, Bangkok, Thailand.King Mongkut's University of Technology Thonburi, Division of Biochemical Technology, School of Bioresources and Technology, Bangkok, Thailand.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

34105981

Citation

Samakkarn, Wiwan, et al. "Reprogramming of the Ethanol Stress Response in Saccharomyces Cerevisiae By the Transcription Factor Znf1 and Its Effect On the Biosynthesis of Glycerol and Ethanol." Applied and Environmental Microbiology, vol. 87, no. 16, 2021, pp. e0058821.
Samakkarn W, Ratanakhanokchai K, Soontorngun N. Reprogramming of the Ethanol Stress Response in Saccharomyces cerevisiae by the Transcription Factor Znf1 and Its Effect on the Biosynthesis of Glycerol and Ethanol. Appl Environ Microbiol. 2021;87(16):e0058821.
Samakkarn, W., Ratanakhanokchai, K., & Soontorngun, N. (2021). Reprogramming of the Ethanol Stress Response in Saccharomyces cerevisiae by the Transcription Factor Znf1 and Its Effect on the Biosynthesis of Glycerol and Ethanol. Applied and Environmental Microbiology, 87(16), e0058821. https://doi.org/10.1128/AEM.00588-21
Samakkarn W, Ratanakhanokchai K, Soontorngun N. Reprogramming of the Ethanol Stress Response in Saccharomyces Cerevisiae By the Transcription Factor Znf1 and Its Effect On the Biosynthesis of Glycerol and Ethanol. Appl Environ Microbiol. 2021 07 27;87(16):e0058821. PubMed PMID: 34105981.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Reprogramming of the Ethanol Stress Response in Saccharomyces cerevisiae by the Transcription Factor Znf1 and Its Effect on the Biosynthesis of Glycerol and Ethanol. AU - Samakkarn,Wiwan, AU - Ratanakhanokchai,Khanok, AU - Soontorngun,Nitnipa, Y1 - 2021/07/27/ PY - 2021/6/10/pubmed PY - 2021/9/29/medline PY - 2021/6/9/entrez KW - S. cerevisiae KW - Znf1 KW - ethanol stress response KW - fermentation KW - glycerol KW - transcription factor KW - unfolded protein response KW - yeasts SP - e0058821 EP - e0058821 JF - Applied and environmental microbiology JO - Appl Environ Microbiol VL - 87 IS - 16 N2 - High ethanol levels can severely inhibit the growth of yeast cells and fermentation productivity. The ethanologenic yeast Saccharomyces cerevisiae activates several well-defined cellular mechanisms of ethanol stress response (ESR); however, the involved regulatory control remains to be characterized. Here, we report a new transcription factor of ethanol stress adaptation called Znf1. It plays a central role in ESR by activating genes for glycerol and fatty acid production (GUP1, GPP1, GPP2, GPD1, GAT1, and OLE1) to preserve plasma membrane integrity. Importantly, Znf1 also activates genes implicated in cell wall biosynthesis (FKS1, SED1, and SMI1) and in the unfolded protein response (HSP30, HSP104, KAR1, and LHS1) to protect cells from proteotoxic stress. The znf1Δ strain displays increased sensitivity to ethanol, the endoplasmic reticulum (ER) stressor β-mercaptoethanol, and the cell wall-perturbing agent calcofluor white. To compensate for a defective cell wall, the strain lacking ZNF1 or its target SMI1 displays increased glycerol levels of 19.6% and 27.7%, respectively. Znf1 collectively regulates an intricate network of target genes essential for growth, protein refolding, and production of key metabolites. Overexpression of ZNF1 not only confers tolerance to high ethanol levels but also increases ethanol production by 4.6% (8.43 g/liter) or 2.8% (75.78 g/liter) when 2% or 20% (wt/vol) glucose, respectively, is used as a substrate, compared to that of the wild-type strain. The mutually stress-responsive transcription factors Msn2/4, Hsf1, and Yap1 are associated with some promoters of Znf1's target genes to promote ethanol stress tolerance. In conclusion, this work implicates the novel regulator Znf1 in coordinating expression of ESR genes and illuminates the unifying transcriptional reprogramming during alcoholic fermentation. IMPORTANCE The yeast S. cerevisiae is a major microbe that is widely used in food and nonfood industries. However, accumulation of ethanol has a negative effect on its growth and limits ethanol production. The Znf1 transcription factor has been implicated as a key regulator of glycolysis and gluconeogenesis in the utilization of different carbon sources, including glucose, the most abundant sugar on earth, and nonfermentable substrates. Here, the role of Znf1 in ethanol stress response is defined. Znf1 actively reprograms expression of genes linked to the unfolded protein response (UPR), heat shock response, glycerol and carbohydrate metabolism, and biosynthesis of cell membrane and cell wall components. A complex interplay among transcription factors of ESR indicates transcriptional fine-tuning as the main mechanism of stress adaptation, and Znf1 plays a major regulatory role in the coordination. Understanding the adaptive ethanol stress mechanism is crucial to engineering robust yeast strains for enhanced stress tolerance or increased ethanol production. SN - 1098-5336 UR - https://www.unboundmedicine.com/medline/citation/34105981/Reprogramming_of_the_Ethanol_Stress_Response_in_Saccharomyces_cerevisiae_by_the_Transcription_Factor_Znf1_and_Its_Effect_on_the_Biosynthesis_of_Glycerol_and_Ethanol_ L2 - https://journals.asm.org/doi/10.1128/AEM.00588-21?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -