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Bourgeois NM, Black JJ, Bhondeley M, Liu Z. Protein Kinase A Negatively Regulates the Acetic Acid Stress Response in S. cerevisiae. Microorganisms 2024; 12:1452. [PMID: 39065219 PMCID: PMC11278818 DOI: 10.3390/microorganisms12071452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2024] [Revised: 07/11/2024] [Accepted: 07/15/2024] [Indexed: 07/28/2024] Open
Abstract
Bioethanol fermentation from lignocellulosic hydrolysates is negatively affected by the presence of acetic acid. The budding yeast S. cerevisiae adapts to acetic acid stress partly by activating the transcription factor, Haa1. Haa1 induces the expression of many genes, which are responsible for increased fitness in the presence of acetic acid. Here, we show that protein kinase A (PKA) is a negative regulator of Haa1-dependent gene expression under both basal and acetic acid stress conditions. Deletions of RAS2, encoding a positive regulator of PKA, and PDE2, encoding a negative regulator of PKA, lead to an increased and decreased expression of Haa1-regulated genes, respectively. Importantly, the deletion of HAA1 largely reverses the effects of ras2∆. Additionally, the expression of a dominant, hyperactive RAS2A18V19 mutant allele also reduces the expression of Haa1-regulated genes. We found that both pde2Δ and RAS2A18V19 reduce cell fitness in response to acetic acid stress, while ras2Δ increases cellular adaptation. There are three PKA catalytic subunits in yeast, encoded by TPK1, TPK2, and TPK3. We show that single mutations in TPK1 and TPK3 lead to the increased expression of Haa1-regulated genes, while tpk2Δ reduces their expression. Among tpk double mutations, tpk1Δ tpk3Δ greatly increases the expression of Haa1-regulated genes. We found that acetic acid stress in a tpk1Δ tpk3Δ double mutant induces a flocculation phenotype, which is reversed by haa1Δ. Our findings reveal PKA to be a negative regulator of the acetic acid stress response and may help engineer yeast strains with increased efficiency of bioethanol fermentation.
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Affiliation(s)
- Natasha M. Bourgeois
- Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148, USA
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA 98109, USA
| | - Joshua J. Black
- Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148, USA
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Manika Bhondeley
- Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148, USA
- Kudo Biotechnology, 117 Kendrick Street, Needham, MA 02494, USA
| | - Zhengchang Liu
- Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148, USA
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2
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Li M, Chu Y, Dong X, Ji H. General mechanisms of weak acid-tolerance and current strategies for the development of tolerant yeasts. World J Microbiol Biotechnol 2023; 40:49. [PMID: 38133718 DOI: 10.1007/s11274-023-03875-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 12/16/2023] [Indexed: 12/23/2023]
Abstract
Yeast cells are often subjected to various types of weak acid stress in the process of industrial production, food processing, and preservation, resulting in growth inhibition and reduced fermentation performance. Under acidic conditions, weak acids enter the near-neutral yeast cytoplasm and dissociate into protons and anions, leading to cytoplasmic acidification and cell damage. Although some yeast strains have developed the ability to survive weak acids, the complexity and diversity of stresses during industrial production still require the application of appropriate strategies for phenotypes improvement. In this review, we summarized current knowledge concerning weak acid stress response and resistance, which may suggest important targets for further construction of more robust strains. We also highlight current feasible strategies for improving the weak acid resistance of yeasts, such as adaptive laboratory evolution, transcription factors engineering, and cell membrane/wall engineering. Moreover, the challenges and perspectives associated with improving the competitiveness of industrial strains are also discussed. This review provides effective strategies for improving the industrial phenotypes of yeast from multiple dimensions in future studies.
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Affiliation(s)
- Mengmeng Li
- Institute of Life Sciences, College of Life and Environmental Science, Wenzhou University, Wenzhou, Zhejiang, 325035, PR China
- Biomedical Collaborative Innovation Center of Zhejiang Province & Engineering Laboratory of Zhejiang Province for Pharmaceutical Development of Growth Factors, Wenzhou University, Wenzhou, Zhejiang, 325035, PR China
| | - Yunfei Chu
- Institute of Life Sciences, College of Life and Environmental Science, Wenzhou University, Wenzhou, Zhejiang, 325035, PR China
- Biomedical Collaborative Innovation Center of Zhejiang Province & Engineering Laboratory of Zhejiang Province for Pharmaceutical Development of Growth Factors, Wenzhou University, Wenzhou, Zhejiang, 325035, PR China
| | - Xiameng Dong
- Department of Agriculture and Biotechnology, Wenzhou Vocational College of Science and Technology, Wenzhou, Zhejiang, 325006, PR China.
| | - Hao Ji
- Institute of Life Sciences, College of Life and Environmental Science, Wenzhou University, Wenzhou, Zhejiang, 325035, PR China.
- Biomedical Collaborative Innovation Center of Zhejiang Province & Engineering Laboratory of Zhejiang Province for Pharmaceutical Development of Growth Factors, Wenzhou University, Wenzhou, Zhejiang, 325035, PR China.
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3
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Zangl I, Beyer R, Gattesco A, Labuda R, Pap IJ, Strauss J, Schüller C. Limosilactobacillus fermentum Limits Candida glabrata Growth by Ergosterol Depletion. Microbiol Spectr 2023; 11:e0332622. [PMID: 36802215 PMCID: PMC10100998 DOI: 10.1128/spectrum.03326-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 01/27/2023] [Indexed: 02/23/2023] Open
Abstract
Candida glabrata is a human-associated opportunistic fungal pathogen. It shares its niche with Lactobacillus spp. in the gastrointestinal and vaginal tract. In fact, Lactobacillus species are thought to competitively prevent Candida overgrowth. We investigated the molecular aspects of this antifungal effect by analyzing the interaction of C. glabrata strains with Limosilactobacillus fermentum. From a collection of clinical C. glabrata isolates, we identified strains with different sensitivities to L. fermentum in coculture. We analyzed the variation of their expression pattern to isolate the specific response to L. fermentum. C. glabrata-L. fermentum coculture induced genes associated with ergosterol biosynthesis, weak acid stress, and drug/chemical stress. L. fermentum coculture depleted C. glabrata ergosterol. The reduction of ergosterol was dependent on the Lactobacillus species, even in coculture with different Candida species. We found a similar ergosterol-depleting effect with other lactobacillus strains (Lactobacillus crispatus and Lactobacillus rhamosus) on Candida albicans, Candida tropicalis, and Candida krusei. The addition of ergosterol improved C. glabrata growth in the coculture. Blocking ergosterol synthesis with fluconazole increased the susceptibility against L. fermentum, which was again mitigated by the addition of ergosterol. In accordance, a C. glabrata Δerg11 mutant, defective in ergosterol biosynthesis, was highly sensitive to L. fermentum. In conclusion, our analysis indicates an unexpected direct function of ergosterol for C. glabrata proliferation in coculture with L. fermentum. IMPORTANCE The yeast Candida glabrata, an opportunistic fungal pathogen, and the bacterium Limosilactobacillus fermentum both inhabit the human gastrointestinal and vaginal tract. Lactobacillus species, belonging to the healthy human microbiome, are thought to prevent C. glabrata infections. We investigated the antifungal effect of Limosilactobacillus fermentum on C. glabrata strains quantitively in vitro. The interaction between C. glabrata and L. fermentum evokes an upregulation of genes required for the synthesis of ergosterol, a sterol constituent of the fungal plasma membrane. We found a dramatic reduction of ergosterol in C. glabrata when it was exposed to L. fermentum. This effect extended to other Candida species and other Lactobacillus species. Furthermore, fungal growth was efficiently suppressed by a combination of L. fermentum and fluconazole, an antifungal drug which inhibits ergosterol synthesis. Thus, fungal ergosterol is a key metabolite for the suppression of C. glabrata by L. fermentum.
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Affiliation(s)
- Isabella Zangl
- University of Natural Resources and Life Sciences, Vienna, Institute of Microbial Genetics, Tulln, Austria
| | - Reinhard Beyer
- University of Natural Resources and Life Sciences, Vienna, Institute of Microbial Genetics, Tulln, Austria
| | - Arianna Gattesco
- University of Natural Resources and Life Sciences, Vienna, Institute of Microbial Genetics, Tulln, Austria
| | - Roman Labuda
- Institute of Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine Vienna, Vienna, Austria
- Bioactive Microbial Metabolites, University of Natural Resources and Life Sciences, Vienna (BOKU), Institute of Microbial Genetics, Tulln, Austria
| | - Ildiko-Julia Pap
- University Hospital of St. Pölten, Institute for Hygiene and Microbiology, St. Pölten, Austria
| | - Joseph Strauss
- University of Natural Resources and Life Sciences, Vienna, Institute of Microbial Genetics, Tulln, Austria
- Bioactive Microbial Metabolites, University of Natural Resources and Life Sciences, Vienna (BOKU), Institute of Microbial Genetics, Tulln, Austria
| | - Christoph Schüller
- University of Natural Resources and Life Sciences, Vienna, Institute of Microbial Genetics, Tulln, Austria
- Core Facility Bioactive Molecules: Screening and Analysis, University of Natural Resources and Life Sciences, Vienna, Austria
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4
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Holland K, Blazeck J. High throughput mutagenesis and screening for yeast engineering. J Biol Eng 2022; 16:37. [PMID: 36575525 PMCID: PMC9793380 DOI: 10.1186/s13036-022-00315-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 12/03/2022] [Indexed: 12/28/2022] Open
Abstract
The eukaryotic yeast Saccharomyces cerevisiae is a model host utilized for whole cell biocatalytic conversions, protein evolution, and scientific inquiries into the pathogenesis of human disease. Over the past decade, the scale and pace of such studies has drastically increased alongside the advent of novel tools for both genome-wide studies and targeted genetic mutagenesis. In this review, we will detail past and present (e.g., CRISPR/Cas) genome-scale screening platforms, typically employed in the context of growth-based selections for improved whole cell phenotype or for mechanistic interrogations. We will further highlight recent advances that enable the rapid and often continuous evolution of biomolecules with improved function. Additionally, we will detail the corresponding advances in high throughput selection and screening strategies that are essential for assessing or isolating cellular and protein improvements. Finally, we will describe how future developments can continue to advance yeast high throughput engineering.
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Affiliation(s)
- Kendreze Holland
- grid.213917.f0000 0001 2097 4943Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia USA ,grid.213917.f0000 0001 2097 4943Bioengineering Program, Georgia Institute of Technology, Atlanta, Georgia USA
| | - John Blazeck
- grid.213917.f0000 0001 2097 4943Bioengineering Program, Georgia Institute of Technology, Atlanta, Georgia USA ,grid.213917.f0000 0001 2097 4943School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia USA
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5
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De novo biosynthesis of rubusoside and rebaudiosides in engineered yeasts. Nat Commun 2022; 13:3040. [PMID: 35650215 PMCID: PMC9160076 DOI: 10.1038/s41467-022-30826-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 05/11/2022] [Indexed: 12/24/2022] Open
Abstract
High-sugar diet causes health problems, many of which can be addressed with the use of sugar substitutes. Rubusoside and rebaudiosides are interesting molecules, considered the next generation of sugar substitutes due to their low-calorie, superior sweetness and organoleptic properties. However, their low abundance in nature makes the traditional plant extraction process neither economical nor environmental-friendly. Here we engineer baker's yeast Saccharomyces cerevisiae as a chassis for the de novo production of rubusoside and rebaudiosides. In this process, we identify multiple issues that limit the production, including rate-liming steps, product stress on cellular fitness and unbalanced metabolic networks. We carry out a systematic engineering strategy to solve these issues, which produces rubusoside and rebaudiosides at titers of 1368.6 mg/L and 132.7 mg/L, respectively. The rubusoside chassis strain here constructed paves the way towards a sustainable, large-scale fermentation-based manufacturing of diverse rebaudiosides.
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Responses of Issatchenkia terricola WJL-G4 upon Citric Acid Stress. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27092664. [PMID: 35566015 PMCID: PMC9102369 DOI: 10.3390/molecules27092664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 04/18/2022] [Accepted: 04/19/2022] [Indexed: 12/01/2022]
Abstract
This study aimed to elucidate the responses of a novel characterized Issatchenkia terricola WJL-G4 against citric acid stress by performing physiological analysis, morphology observation, and structural and membrane fatty acid composition analysis. The results showed that under citric acid stress, the cell vitality of I. terricola WJL-G4 was reduced. The cell morphology changed with the unclear, uncompleted and thinner cell wall, and degraded the cell structure. When the citric acid concentration was 20 g/L, I. terricola WJL-G4 could tolerate citric acid and maintain the cell structure by increasing the intracellular pH, superoxide dismutase activity, and contents of unsaturated fatty acids. As the citric acid concentration was ≥80 g/L, the stress has exceeded the cellular anti-stress ability, causing substantial cell damage. The cell membrane permeability, the content of membrane lipids, malondialdehyde and superoxide anion increased, but the intracellular pH and superoxide dismutase activities decreased, accompanying the increase of citric acid concentrations. The findings of this work provided a theoretical basis for the responsive mechanism of I. terricola WJL-G4 under high concentrations of citric acid, and can serve as a reference for biological acid reduction in fruit processing.
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7
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Miyake R, Ling H, Foo JL, Fugono N, Chang MW. Transporter-Driven Engineering of a Genetic Biosensor for the Detection and Production of Short-Branched Chain Fatty Acids in Saccharomyces cerevisiae. Front Bioeng Biotechnol 2022; 10:838732. [PMID: 35372305 PMCID: PMC8975619 DOI: 10.3389/fbioe.2022.838732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Accepted: 02/28/2022] [Indexed: 12/02/2022] Open
Abstract
Biosensors can be used for real-time monitoring of metabolites and high-throughput screening of producer strains. Use of biosensors has facilitated strain engineering to efficiently produce value-added compounds. Following our recent work on the production of short branched-chain fatty acids (SBCFAs) in engineered Saccharomyces cerevisiae, here we harnessed a weak organic acid transporter Pdr12p, engineered a whole-cell biosensor to detect exogenous and intracellular SBCFAs and optimized the biosensor’s performance by varying PDR12 expression. We firstly constructed the biosensor and evaluated its response to a range of short-chain carboxylic acids. Next, we optimized its sensitivity and operational range by deletion and overexpression of PDR12. We found that the biosensor responded to exogenous SBCFAs including isovaleric acid, isobutyric acid and 2-methylbutanoic acid. PDR12 deletion enhanced the biosensor’s sensitivity to isovaleric acid at a low concentration and PDR12 overexpression shifted the operational range towards a higher concentration. Lastly, the deletion of PDR12 improved the biosensor’s sensitivity to the SBCFAs produced in our previously engineered SBCFA-overproducing strain. To our knowledge, our work represents the first study on employing an ATP-binding-cassette transporter to engineer a transcription-factor-based genetic biosensor for sensing SBCFAs in S. cerevisiae. Our findings provide useful insights into SBCFA detection by a genetic biosensor that will facilitate the screening of SBCFA-overproducing strains.
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Affiliation(s)
- Ryoma Miyake
- NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), National University of Singapore, Singapore, Singapore
- Synthetic Biology Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Science & Innovation Center, Mitsubishi Chemical Corporation, Yokohama, Japan
| | - Hua Ling
- NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), National University of Singapore, Singapore, Singapore
- Synthetic Biology Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Jee Loon Foo
- NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), National University of Singapore, Singapore, Singapore
- Synthetic Biology Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Nobutake Fugono
- Science & Innovation Center, Mitsubishi Chemical Corporation, Yokohama, Japan
| | - Matthew Wook Chang
- NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), National University of Singapore, Singapore, Singapore
- Synthetic Biology Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- *Correspondence: Matthew Wook Chang,
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8
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The Role of Plasma Membrane Pleiotropic Drug Resistance Transporters in the Killer Activity of Debaryomyces hansenii and Wickerhamomyces anomalus Toxins. Toxins (Basel) 2022; 14:toxins14030180. [PMID: 35324677 PMCID: PMC8955487 DOI: 10.3390/toxins14030180] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 02/22/2022] [Accepted: 02/24/2022] [Indexed: 02/04/2023] Open
Abstract
The killer strains of Debaryomyces hansenii and Wickerhamomyces anomalus species secrete antimicrobial proteins called killer toxins which are active against selected fungal phytopathogens. In our research, we attempted to investigate the role of plasma membrane pleiotropic drug resistance (PDR) transporters (Pdr5p and Snq2p) in the mechanism of defense against killer toxins. Saccharomyces cerevisiae mutant strains with strengthened or weakened pleiotropic drug resistance due to increased or reduced number of mentioned PDR efflux pumps were tested for killer toxin susceptibility. The present study demonstrates the influence of the Snq2p efflux pump in immunity to W.anomalus BS91 killer toxin. It was also shown that the activity of killer toxins of D. hansenii AII4b, KI2a, MI1a and CBS767 strains is regulated by other transporters than those influencing W. anomalus killer toxin activity. In turn, this might be related to the functioning of the Pdr5p transporter and a complex cross-talk between several regulatory multidrug resistance networks. To the best of our knowledge, this is the first study that reports the involvement of PDR transporters in the cell membrane of susceptible microorganisms in resistance to killer yeasts’ toxins.
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9
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Seekles SJ, van Dam J, Arentshorst M, Ram AFJ. Natural Variation and the Role of Zn 2Cys 6 Transcription Factors SdrA, WarA and WarB in Sorbic Acid Resistance of Aspergillus niger. Microorganisms 2022; 10:microorganisms10020221. [PMID: 35208676 PMCID: PMC8877037 DOI: 10.3390/microorganisms10020221] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 01/16/2022] [Accepted: 01/18/2022] [Indexed: 02/07/2023] Open
Abstract
Weak acids, such as sorbic acid, are used as chemical food preservatives by the industry. Fungi overcome this weak-acid stress by inducing cellular responses mediated by transcription factors. In our research, a large-scale sorbic acid resistance screening was performed on 100 A. niger sensu stricto strains isolated from various sources to study strain variability in sorbic acid resistance. The minimal inhibitory concentration of undissociated (MICu) sorbic acid at pH = 4 in the MEB of the A. niger strains varies between 4.0 mM and 7.0 mM, with the average out of 100 strains being 4.8 ± 0.8 mM, when scored after 28 days. MICu values were roughly 1 mM lower when tested in commercial ice tea. Genome sequencing of the most sorbic-acid-sensitive strain among the isolates revealed a premature stop codon inside the sorbic acid response regulator encoding gene sdrA. Repairing this missense mutation increased the sorbic acid resistance, showing that the sorbic-acid-sensitive phenotype of this strain is caused by the loss of SdrA function. To identify additional transcription factors involved in weak-acid resistance, a transcription factor knock-out library consisting of 240 A. niger deletion strains was screened. The screen identified a novel transcription factor, WarB, which contributes to the resistance against a broad range of weak acids, including sorbic acid. The roles of SdrA, WarA and WarB in weak-acid resistance, including sorbic acid, were compared by creating single, double and the triple knock-out strains. All three transcription factors were found to have an additive effect on the sorbic acid stress response.
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Affiliation(s)
- Sjoerd J. Seekles
- TIFN, Agro Business Park 82, 6708 PW Wageningen, The Netherlands;
- Department Molecular Microbiology and Biotechnology, Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands; (J.v.D.); (M.A.)
| | - Jisca van Dam
- Department Molecular Microbiology and Biotechnology, Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands; (J.v.D.); (M.A.)
| | - Mark Arentshorst
- Department Molecular Microbiology and Biotechnology, Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands; (J.v.D.); (M.A.)
| | - Arthur F. J. Ram
- TIFN, Agro Business Park 82, 6708 PW Wageningen, The Netherlands;
- Department Molecular Microbiology and Biotechnology, Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands; (J.v.D.); (M.A.)
- Correspondence:
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10
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Baumann L, Bruder S, Kabisch J, Boles E, Oreb M. High-Throughput Screening of an Octanoic Acid Producer Strain Library Enables Detection of New Targets for Increasing Titers in Saccharomyces cerevisiae. ACS Synth Biol 2021; 10:1077-1086. [PMID: 33979526 DOI: 10.1021/acssynbio.0c00600] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Octanoic acid is an industrially relevant compound with applications in antimicrobials or as a precursor for biofuels. Microbial biosynthesis through yeast is a promising alternative to current unsustainable production methods. To increase octanoic acid titers in Saccharomyces cerevisiae, we use a previously developed biosensor that is based on the octanoic acid responsive pPDR12 promotor coupled to GFP. We establish a biosensor strain amenable for high-throughput screening of an octanoic acid producer strain library. Through development, optimization, and execution of a high-throughput screening approach, we were able to detect two new genetic targets, KCS1 and FSH2, which increased octanoic acid titers through combined overexpression by about 55% compared to the parental strain. Neither target has yet been reported to be involved in fatty acid biosynthesis. The presented methodology can be employed to screen any genetic library and thereby more genes involved in improving octanoic acid production can be detected in the future.
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Affiliation(s)
- Leonie Baumann
- Institute of Molecular Biosciences, Faculty of Biological Sciences, Goethe University Frankfurt, Max-von-Laue Straße 9, 60438 Frankfurt am Main, Germany
| | - Stefan Bruder
- Department of Biology, Computer-aided Synthetic Biology, Technical University Darmstadt, Schnittspahnstr. 1, 64287 Darmstadt, Germany
| | - Johannes Kabisch
- Department of Biology, Computer-aided Synthetic Biology, Technical University Darmstadt, Schnittspahnstr. 1, 64287 Darmstadt, Germany
| | - Eckhard Boles
- Institute of Molecular Biosciences, Faculty of Biological Sciences, Goethe University Frankfurt, Max-von-Laue Straße 9, 60438 Frankfurt am Main, Germany
| | - Mislav Oreb
- Institute of Molecular Biosciences, Faculty of Biological Sciences, Goethe University Frankfurt, Max-von-Laue Straße 9, 60438 Frankfurt am Main, Germany
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11
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Fletcher E, Mercurio K, Walden EA, Baetz K. A yeast chemogenomic screen identifies pathways that modulate adipic acid toxicity. iScience 2021; 24:102327. [PMID: 33889823 PMCID: PMC8050732 DOI: 10.1016/j.isci.2021.102327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 02/19/2021] [Accepted: 03/15/2021] [Indexed: 11/18/2022] Open
Abstract
Adipic acid production by yeast fermentation is gaining attention as a renewable source of platform chemicals for making nylon products. However, adipic acid toxicity inhibits yeast growth and fermentation. Here, we performed a chemogenomic screen in Saccharomyces cerevisiae to understand the cellular basis of adipic acid toxicity. Our screen revealed that KGD1 (a key gene in the tricarboxylic acid cycle) deletion improved tolerance to adipic acid and its toxic precursor, catechol. Conversely, disrupting ergosterol biosynthesis as well as protein trafficking and vacuolar transport resulted in adipic acid hypersensitivity. Notably, we show that adipic acid disrupts the Membrane Compartment of Can1 (MCC) on the plasma membrane and impacts endocytosis. This was evidenced by the rapid internalization of Can1 for vacuolar degradation. As ergosterol is an essential component of the MCC and protein trafficking mechanisms are required for endocytosis, we highlight the importance of these cellular processes in modulating adipic acid toxicity. Deletion of the TCA cycle gene KGD1 improves tolerance to adipic acid and catechol Ergosterol and Pdr12 play non-overlapping roles protecting cell from adipic acid Adipic acid-induced plasma membrane localization of Pdr12 is independent of ergosterol Adipic acid disrupts the Membrane Compartment of Can1 (MCC) and induces endocytosis
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Affiliation(s)
- Eugene Fletcher
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada
| | - Kevin Mercurio
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada
| | - Elizabeth A. Walden
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada
| | - Kristin Baetz
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada
- Corresponding author
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12
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Liang L, Liu R, Freed EF, Eckert CA, Gill RT. Transcriptional Regulatory Networks Involved in C3-C4 Alcohol Stress Response and Tolerance in Yeast. ACS Synth Biol 2021; 10:19-28. [PMID: 33356165 DOI: 10.1021/acssynbio.0c00253] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Alcohol toxicity significantly impacts the titer and productivity of industrially produced biofuels. To overcome this limitation, we must find and use strategies to improve stress tolerance in production strains. Previously, we developed a multiplex navigation of a global regulatory network (MINR) library that targeted 25 regulatory genes that are predicted to modify global regulation in yeast under different stress conditions. In this study, we expanded this concept to target the active sites of 47 transcriptional regulators using a saturation mutagenesis library. The 47 targeted regulators interact with more than half of all yeast genes. We then screened and selected for C3-C4 alcohol tolerance. We identified specific mutants that have resistance to isopropanol and isobutanol. Notably, the WAR1_K110N variant improved tolerance to both isopropanol and isobutanol. In addition, we investigated the mechanisms for improvement of isopropanol and isobutanol stress tolerance and found that genes related to glycolysis play a role in tolerance to isobutanol, while changes in ATP synthesis and mitochondrial respiration play a role in tolerance to both isobutanol and isopropanol. Overall, this work sheds light on basic mechanisms for isopropanol and isobutanol toxicity and demonstrates a promising strategy to improve tolerance to C3-C4 alcohols by perturbing the transcriptional regulatory network.
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Affiliation(s)
- Liya Liang
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder 80303, Colorado United States
| | - Rongming Liu
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder 80303, Colorado United States
| | - Emily F Freed
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder 80303, Colorado United States
| | - Carrie A Eckert
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder 80303, Colorado United States
- National Renewable Energy Laboratory (NREL), Golden 80401, Colorado United States
| | - Ryan T Gill
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder 80303, Colorado United States
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby DK-2800, Denmark
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Buechel ER, Pinkett HW. Transcription factors and ABC transporters: from pleiotropic drug resistance to cellular signaling in yeast. FEBS Lett 2020; 594:3943-3964. [PMID: 33089887 DOI: 10.1002/1873-3468.13964] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 09/07/2020] [Accepted: 10/15/2020] [Indexed: 12/24/2022]
Abstract
Budding yeast Saccharomyces cerevisiae survives in microenvironments utilizing networks of regulators and ATP-binding cassette (ABC) transporters to circumvent toxins and a variety of drugs. Our understanding of transcriptional regulation of ABC transporters in yeast is mainly derived from the study of multidrug resistance protein networks. Over the past two decades, this research has not only expanded the role of transcriptional regulators in pleiotropic drug resistance (PDR) but evolved to include the role that regulators play in cellular signaling and environmental adaptation. Inspection of the gene networks of the transcriptional regulators and characterization of the ABC transporters has clarified that they also contribute to environmental adaptation by controlling plasma membrane composition, toxic-metal sequestration, and oxidative stress adaptation. Additionally, ABC transporters and their regulators appear to be involved in cellular signaling for adaptation of S. cerevisiae populations to nutrient availability. In this review, we summarize the current understanding of the S. cerevisiae transcriptional regulatory networks and highlight recent work in other notable fungal organisms, underlining the expansion of the study of these gene networks across the kingdom fungi.
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Affiliation(s)
- Evan R Buechel
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Heather W Pinkett
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
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Ndukwe JK, Aliyu GO, Onwosi CO, Chukwu KO, Ezugworie FN. Mechanisms of weak acid-induced stress tolerance in yeasts: Prospects for improved bioethanol production from lignocellulosic biomass. Process Biochem 2020. [DOI: 10.1016/j.procbio.2019.11.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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15
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Weak Acid Resistance A (WarA), a Novel Transcription Factor Required for Regulation of Weak-Acid Resistance and Spore-Spore Heterogeneity in Aspergillus niger. mSphere 2020; 5:5/1/e00685-19. [PMID: 31915214 PMCID: PMC6952191 DOI: 10.1128/msphere.00685-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Weak acids are widely used as food preservatives, as they are very effective at preventing the growth of most species of bacteria and fungi. However, some species of molds can survive and grow in the concentrations of weak acid employed in food and drink products, thereby causing spoilage with resultant risks for food security and health. Current knowledge of weak-acid resistance mechanisms in these fungi is limited, especially in comparison to that in yeasts. We characterized gene functions in the spoilage mold species Aspergillus niger which are important for survival and growth in the presence of weak-acid preservatives. Such identification of weak-acid resistance mechanisms in spoilage molds will help in the design of new strategies to reduce food spoilage in the future. Propionic, sorbic, and benzoic acids are organic weak acids that are widely used as food preservatives, where they play a critical role in preventing microbial growth. In this study, we uncovered new mechanisms of weak-acid resistance in molds. By screening a library of 401 transcription factor deletion strains in Aspergillus fumigatus for sorbic acid hypersensitivity, a previously uncharacterized transcription factor was identified and named weak acid resistance A (WarA). The orthologous gene in the spoilage mold Aspergillus niger was identified and deleted. WarA was required for resistance to a range of weak acids, including sorbic, propionic, and benzoic acids. A transcriptomic analysis was performed to characterize genes regulated by WarA during sorbic acid treatment in A. niger. Several genes were significantly upregulated in the wild type compared with a ΔwarA mutant, including genes encoding putative weak-acid detoxification enzymes and transporter proteins. Among these was An14g03570, a putative ABC-type transporter which we found to be required for weak-acid resistance in A. niger. We also show that An14g03570 is a functional homologue of the Saccharomyces cerevisiae protein Pdr12p and we therefore name it PdrA. Last, resistance to sorbic acid was found to be highly heterogeneous within genetically uniform populations of ungerminated A. niger conidia, and we demonstrate that pdrA is a determinant of this heteroresistance. This study has identified novel mechanisms of weak-acid resistance in A. niger which could help inform and improve future food spoilage prevention strategies. IMPORTANCE Weak acids are widely used as food preservatives, as they are very effective at preventing the growth of most species of bacteria and fungi. However, some species of molds can survive and grow in the concentrations of weak acid employed in food and drink products, thereby causing spoilage with resultant risks for food security and health. Current knowledge of weak-acid resistance mechanisms in these fungi is limited, especially in comparison to that in yeasts. We characterized gene functions in the spoilage mold species Aspergillus niger which are important for survival and growth in the presence of weak-acid preservatives. Such identification of weak-acid resistance mechanisms in spoilage molds will help in the design of new strategies to reduce food spoilage in the future.
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Pereira R, Wei Y, Mohamed E, Radi M, Malina C, Herrgård MJ, Feist AM, Nielsen J, Chen Y. Adaptive laboratory evolution of tolerance to dicarboxylic acids in Saccharomyces cerevisiae. Metab Eng 2019; 56:130-141. [DOI: 10.1016/j.ymben.2019.09.008] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 09/19/2019] [Accepted: 09/19/2019] [Indexed: 11/16/2022]
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17
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Liang T, Xiao W, Zeng B, He B. Transcriptome Analysis of the Zn(II)2Cys6 Zinc Cluster-encoding Gene Family in Aspergillus Oryzae. PROCEEDINGS OF THE 2019 8TH INTERNATIONAL CONFERENCE ON BIOINFORMATICS AND BIOMEDICAL SCIENCE 2019. [DOI: 10.1145/3369166.3369194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Affiliation(s)
- Tiantian Liang
- Jiangxi Science & Technology, Normal University, Nanchang, Jiangxi, China
| | - Wenxu Xiao
- Jiangxi Science & Technology, Normal University, Nanchang, Jiangxi, China
| | - Bin Zeng
- Jiangxi Science & Technology, Normal University, Nanchang, Jiangxi, China
| | - Bin He
- Jiangxi Science & Technology, Normal University, Nanchang, Jiangxi, China
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Kim MS, Cho KH, Park KH, Jang J, Hahn JS. Activation of Haa1 and War1 transcription factors by differential binding of weak acid anions in Saccharomyces cerevisiae. Nucleic Acids Res 2019; 47:1211-1224. [PMID: 30476185 PMCID: PMC6379682 DOI: 10.1093/nar/gky1188] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 10/31/2018] [Accepted: 11/07/2018] [Indexed: 01/03/2023] Open
Abstract
In Saccharomyces cerevisiae, Haa1 and War1 transcription factors are involved in cellular adaptation against hydrophilic weak acids and lipophilic weak acids, respectively. However, it is unclear how these transcription factors are differentially activated depending on the identity of the weak acid. Using a field-effect transistor (FET)-type biosensor based on carbon nanofibers, in the present study we demonstrate that Haa1 and War1 directly bind to various weak acid anions with different affinities. Haa1 is most sensitive to acetate, followed by lactate, whereas War1 is most sensitive to benzoate, followed by sorbate, reflecting their differential activation during weak acid stresses. We show that DNA binding by Haa1 is induced in the presence of acetic acid and that the N-terminal Zn-binding domain is essential for this activity. Acetate binds to the N-terminal 150-residue region, and the transcriptional activation domain is located between amino acid residues 230 and 483. Our data suggest that acetate binding converts an inactive Haa1 to the active form, which is capable of DNA binding and transcriptional activation.
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Affiliation(s)
- Myung Sup Kim
- School of Chemical and Biological Engineering, Seoul National University, Institute of Chemical Processes, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Kyung Hee Cho
- School of Chemical and Biological Engineering, Seoul National University, Institute of Chemical Processes, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Kwang Hyun Park
- School of Chemical and Biological Engineering, Seoul National University, Institute of Chemical Processes, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Jyongsik Jang
- School of Chemical and Biological Engineering, Seoul National University, Institute of Chemical Processes, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Ji-Sook Hahn
- School of Chemical and Biological Engineering, Seoul National University, Institute of Chemical Processes, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
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19
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Vanacloig-Pedros E, Lozano-Pérez C, Alarcón B, Pascual-Ahuir A, Proft M. Live-cell assays reveal selectivity and sensitivity of the multidrug response in budding yeast. J Biol Chem 2019; 294:12933-12946. [PMID: 31296662 DOI: 10.1074/jbc.ra119.009291] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 07/04/2019] [Indexed: 11/06/2022] Open
Abstract
Pleiotropic drug resistance arises by the enhanced extrusion of bioactive molecules and is present in a wide range of organisms, ranging from fungi to human cells. A key feature of this adaptation is the sensitive detection of intracellular xenobiotics by transcriptional activators, activating expression of multiple drug exporters. Here, we investigated the selectivity and sensitivity of the budding yeast (Saccharomyces cerevisiae) multidrug response to better understand how differential drug recognition leads to specific activation of drug exporter genes and to drug resistance. Applying live-cell luciferase reporters, we demonstrate that the SNQ2, PDR5, PDR15, and YOR1 transporter genes respond to different mycotoxins, menadione, and hydrogen peroxide in a distinguishable manner and with characteristic amplitudes, dynamics, and sensitivities. These responses correlated with differential sensitivities of the respective transporter mutants to the specific xenobiotics. We further establish a binary vector system, enabling quantitative determination of xenobiotic-transcription factor (TF) interactions in real time. Applying this system we found that the TFs Pdr1, Pdr3, Yrr1, Stb5, and Pdr8 have largely different drug recognition patterns. We noted that Pdr1 is the most promiscuous activator, whereas Yrr1 and Stb5 are selective for ochratoxin A and hydrogen peroxide, respectively. We also show that Pdr1 is rapidly degraded after xenobiotic exposure, which leads to a desensitization of the Pdr1-specific response upon repeated activation. The findings of our work indicate that in the yeast multidrug system, several transcriptional activators with distinguishable selectivities trigger differential activation of the transporter genes.
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Affiliation(s)
- Elena Vanacloig-Pedros
- Department of Biotechnology, Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València, 46022 Valencia, Spain
| | - Carlos Lozano-Pérez
- Department of Molecular and Cellular Pathology and Therapy, Instituto de Biomedicina de Valencia IBV-CSIC, 46010 Valencia, Spain
| | - Benito Alarcón
- Department of Molecular and Cellular Pathology and Therapy, Instituto de Biomedicina de Valencia IBV-CSIC, 46010 Valencia, Spain
| | - Amparo Pascual-Ahuir
- Department of Biotechnology, Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València, 46022 Valencia, Spain.
| | - Markus Proft
- Department of Molecular and Cellular Pathology and Therapy, Instituto de Biomedicina de Valencia IBV-CSIC, 46010 Valencia, Spain.
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20
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Baumann L, Rajkumar AS, Morrissey JP, Boles E, Oreb M. A Yeast-Based Biosensor for Screening of Short- and Medium-Chain Fatty Acid Production. ACS Synth Biol 2018; 7:2640-2646. [PMID: 30338986 DOI: 10.1021/acssynbio.8b00309] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Short- and medium-chain fatty acids (SMCFA) are important platform chemicals currently produced from nonsustainable resources. The engineering of microbial cells to produce SMCFA, however, lacks high-throughput methods to screen for best performing cells. Here, we present the development of a whole-cell biosensor for easy and rapid detection of SMCFA. The biosensor is based on a multicopy yeast plasmid containing the SMCFA-responsive PDR12 promoter coupled to GFP as the reporter gene. The sensor detected hexanoic, heptanoic and octanoic acid over a linear range up to 2, 1.5, and 0.75 mM, respectively, but did not show a linear response to decanoic and dodecanoic acid. We validated the functionality of the biosensor with culture supernatants of a previously engineered Saccharomyces cerevisiae octanoic acid producer strain and derivatives thereof. The biosensor signal correlated strongly with the octanoic acid concentrations as determined by gas chromatography. Thus, this biosensor enables the high-throughput screening of SMCFA producers and has the potential to drastically speed up the engineering of diverse SMCFA producing cell factories.
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Affiliation(s)
- Leonie Baumann
- Institute of Molecular Biosciences, Faculty of Biological Sciences, Goethe University Frankfurt, Max-von-Laue Straße 9, 60438 Frankfurt am Main, Germany
| | - Arun S. Rajkumar
- School of Microbiology, Centre for Synthetic Biology and Biotechnology, Environmental Research Institute, APC Microbiome Institute, University College Cork, Cork T12 YN60, Ireland
| | - John P. Morrissey
- School of Microbiology, Centre for Synthetic Biology and Biotechnology, Environmental Research Institute, APC Microbiome Institute, University College Cork, Cork T12 YN60, Ireland
| | - Eckhard Boles
- Institute of Molecular Biosciences, Faculty of Biological Sciences, Goethe University Frankfurt, Max-von-Laue Straße 9, 60438 Frankfurt am Main, Germany
| | - Mislav Oreb
- Institute of Molecular Biosciences, Faculty of Biological Sciences, Goethe University Frankfurt, Max-von-Laue Straße 9, 60438 Frankfurt am Main, Germany
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21
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Cunha JT, Romaní A, Costa CE, Sá-Correia I, Domingues L. Molecular and physiological basis of Saccharomyces cerevisiae tolerance to adverse lignocellulose-based process conditions. Appl Microbiol Biotechnol 2018; 103:159-175. [PMID: 30397768 DOI: 10.1007/s00253-018-9478-3] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 10/19/2018] [Accepted: 10/22/2018] [Indexed: 11/27/2022]
Abstract
Lignocellulose-based biorefineries have been gaining increasing attention to substitute current petroleum-based refineries. Biomass processing requires a pretreatment step to break lignocellulosic biomass recalcitrant structure, which results in the release of a broad range of microbial inhibitors, mainly weak acids, furans, and phenolic compounds. Saccharomyces cerevisiae is the most commonly used organism for ethanol production; however, it can be severely distressed by these lignocellulose-derived inhibitors, in addition to other challenging conditions, such as pentose sugar utilization and the high temperatures required for an efficient simultaneous saccharification and fermentation step. Therefore, a better understanding of the yeast response and adaptation towards the presence of these multiple stresses is of crucial importance to design strategies to improve yeast robustness and bioconversion capacity from lignocellulosic biomass. This review includes an overview of the main inhibitors derived from diverse raw material resultants from different biomass pretreatments, and describes the main mechanisms of yeast response to their presence, as well as to the presence of stresses imposed by xylose utilization and high-temperature conditions, with a special emphasis on the synergistic effect of multiple inhibitors/stressors. Furthermore, successful cases of tolerance improvement of S. cerevisiae are highlighted, in particular those associated with other process-related physiologically relevant conditions. Decoding the overall yeast response mechanisms will pave the way for the integrated development of sustainable yeast cell-based biorefineries.
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Affiliation(s)
- Joana T Cunha
- Centre of Biological Engineering (CEB), University of Minho, 4710-057, Braga, Portugal
| | - Aloia Romaní
- Centre of Biological Engineering (CEB), University of Minho, 4710-057, Braga, Portugal
| | - Carlos E Costa
- Centre of Biological Engineering (CEB), University of Minho, 4710-057, Braga, Portugal
| | - Isabel Sá-Correia
- Institute for Bioengineering and Biosciences, Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisbon, Portugal
| | - Lucília Domingues
- Centre of Biological Engineering (CEB), University of Minho, 4710-057, Braga, Portugal.
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A semi-synthetic regulon enables rapid growth of yeast on xylose. Nat Commun 2018; 9:1233. [PMID: 29581426 PMCID: PMC5964326 DOI: 10.1038/s41467-018-03645-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 03/01/2018] [Indexed: 01/27/2023] Open
Abstract
Nutrient assimilation is the first step that allows biological systems to proliferate and produce value-added products. Yet, implementation of heterologous catabolic pathways has so far relied on constitutive gene expression without consideration for global regulatory systems that may enhance nutrient assimilation and cell growth. In contrast, natural systems prefer nutrient-responsive gene regulation (called regulons) that control multiple cellular functions necessary for cell survival and growth. Here, in Saccharomyces cerevisiae, by partially- and fully uncoupling galactose (GAL)-responsive regulation and metabolism, we demonstrate the significant growth benefits conferred by the GAL regulon. Next, by adapting the various aspects of the GAL regulon for a non-native nutrient, xylose, we build a semi-synthetic regulon that exhibits higher growth rate, better nutrient consumption, and improved growth fitness compared to the traditional and ubiquitous constitutive expression strategy. This work provides an elegant paradigm to integrate non-native nutrient catabolism with native, global cellular responses to support fast growth. Efficient assimilation of nutrients is essential for the production of value-added products in microbial fermentation. Here the authors design a semi-synthetic xylose regulon to improve growth characteristics of Saccharomyces cerevisiae on this non-native sugar.
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23
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Wu G, Xu Z, Jönsson LJ. Profiling of Saccharomyces cerevisiae transcription factors for engineering the resistance of yeast to lignocellulose-derived inhibitors in biomass conversion. Microb Cell Fact 2017; 16:199. [PMID: 29137634 PMCID: PMC5686817 DOI: 10.1186/s12934-017-0811-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 11/04/2017] [Indexed: 11/24/2022] Open
Abstract
Background Yeast transcription factors (TFs) involved in the regulation of multidrug resistance (MDR) were investigated in experiments with deletion mutants, transformants overexpressing synthetic genes encoding TFs, and toxic concentrations of lignocellulose-derived substances added to cultures as complex mixtures or as specific compounds, viz. coniferyl aldehyde, 5-hydroxymethylfurfural, and furfural. Results In the presence of complex mixtures of toxic substances from spruce wood, transformants overexpressing YAP1 and STB5, TFs involved in oxidative stress response, exhibited enhanced relative growth rates amounting to 4.589 ± 0.261 and 1.455 ± 0.185, respectively. Other TFs identified as important for resistance included DAL81, GZF3, LEU3, PUT3, and WAR1. Potential overlapping functions of YAP1 and STB5 were investigated in experiments with permutations of deletions and overexpression of the two genes. YAP1 complemented STB5 with respect to resistance to 5-hydroxymethylfurfural, but had a distinct role with regard to resistance to coniferyl aldehyde as deletion of YAP1 rendered the cell incapable of resisting coniferyl aldehyde even if STB5 was overexpressed. Conclusions We have investigated 30 deletion mutants and eight transformants overexpressing MDR transcription factors with regard to the roles the transcription factors play in the resistance to toxic concentrations of lignocellulose-derived substances. This work provides an overview of the involvement of thirty transcription factors in the resistance to lignocellulose-derived substances, shows distinct and complementary roles played by YAP1 and STB5, and offers directions for the engineering of robust yeast strains for fermentation processes based on lignocellulosic feedstocks.![]() Electronic supplementary material The online version of this article (10.1186/s12934-017-0811-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Guochao Wu
- Department of Chemistry, Umeå University, 901 87, Umeå, Sweden.
| | - Zixiang Xu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Leif J Jönsson
- Department of Chemistry, Umeå University, 901 87, Umeå, Sweden
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Laboratory Evolution of a Biotin-Requiring Saccharomyces cerevisiae Strain for Full Biotin Prototrophy and Identification of Causal Mutations. Appl Environ Microbiol 2017; 83:AEM.00892-17. [PMID: 28600311 DOI: 10.1128/aem.00892-17] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 06/01/2017] [Indexed: 11/20/2022] Open
Abstract
Biotin prototrophy is a rare, incompletely understood, and industrially relevant characteristic of Saccharomyces cerevisiae strains. The genome of the haploid laboratory strain CEN.PK113-7D contains a full complement of biotin biosynthesis genes, but its growth in biotin-free synthetic medium is extremely slow (specific growth rate [μ] ≈ 0.01 h-1). Four independent evolution experiments in repeated batch cultures and accelerostats yielded strains whose growth rates (μ ≤ 0.36 h-1) in biotin-free and biotin-supplemented media were similar. Whole-genome resequencing of these evolved strains revealed up to 40-fold amplification of BIO1, which encodes pimeloyl-coenzyme A (CoA) synthetase. The additional copies of BIO1 were found on different chromosomes, and its amplification coincided with substantial chromosomal rearrangements. A key role of this gene amplification was confirmed by overexpression of BIO1 in strain CEN.PK113-7D, which enabled growth in biotin-free medium (μ = 0.15 h-1). Mutations in the membrane transporter genes TPO1 and/or PDR12 were found in several of the evolved strains. Deletion of TPO1 and PDR12 in a BIO1-overexpressing strain increased its specific growth rate to 0.25 h-1 The effects of null mutations in these genes, which have not been previously associated with biotin metabolism, were nonadditive. This study demonstrates that S. cerevisiae strains that carry the basic genetic information for biotin synthesis can be evolved for full biotin prototrophy and identifies new targets for engineering biotin prototrophy into laboratory and industrial strains of this yeast.IMPORTANCE Although biotin (vitamin H) plays essential roles in all organisms, not all organisms can synthesize this vitamin. Many strains of baker's yeast, an important microorganism in industrial biotechnology, contain at least some of the genes required for biotin synthesis. However, most of these strains cannot synthesize biotin at all or do so at rates that are insufficient to sustain fast growth and product formation. Consequently, this expensive vitamin is routinely added to baker's yeast cultures. In this study, laboratory evolution in biotin-free growth medium yielded new strains that grew as fast in the absence of biotin as in its presence. By analyzing the DNA sequences of evolved biotin-independent strains, mutations were identified that contributed to this ability. This work demonstrates full biotin independence of an industrially relevant yeast and identifies mutations whose introduction into other yeast strains may reduce or eliminate their biotin requirements.
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25
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Brown AJP, Cowen LE, di Pietro A, Quinn J. Stress Adaptation. Microbiol Spectr 2017; 5:10.1128/microbiolspec.FUNK-0048-2016. [PMID: 28721857 PMCID: PMC5701650 DOI: 10.1128/microbiolspec.funk-0048-2016] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Indexed: 01/21/2023] Open
Abstract
Fungal species display an extraordinarily diverse range of lifestyles. Nevertheless, the survival of each species depends on its ability to sense and respond to changes in its natural environment. Environmental changes such as fluctuations in temperature, water balance or pH, or exposure to chemical insults such as reactive oxygen and nitrogen species exert stresses that perturb cellular homeostasis and cause molecular damage to the fungal cell. Consequently, fungi have evolved mechanisms to repair this damage, detoxify chemical insults, and restore cellular homeostasis. Most stresses are fundamental in nature, and consequently, there has been significant evolutionary conservation in the nature of the resultant responses across the fungal kingdom and beyond. For example, heat shock generally induces the synthesis of chaperones that promote protein refolding, antioxidants are generally synthesized in response to an oxidative stress, and osmolyte levels are generally increased following a hyperosmotic shock. In this article we summarize the current understanding of these and other stress responses as well as the signaling pathways that regulate them in the fungi. Model yeasts such as Saccharomyces cerevisiae are compared with filamentous fungi, as well as with pathogens of plants and humans. We also discuss current challenges associated with defining the dynamics of stress responses and with the elaboration of fungal stress adaptation under conditions that reflect natural environments in which fungal cells may be exposed to different types of stresses, either sequentially or simultaneously.
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Affiliation(s)
- Alistair J P Brown
- Medical Research Council Centre for Medical Mycology at the University of Aberdeen, Aberdeen Fungal Group, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, United Kingdom
| | - Leah E Cowen
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Antonio di Pietro
- Departamento de Genética, Universidad de Córdoba, Campus de Rabanales, Edificio Gregor Mendel C5, 14071 Córdoba, Spain
| | - Janet Quinn
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
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Williams TC, Xu X, Ostrowski M, Pretorius IS, Paulsen IT. Positive-feedback, ratiometric biosensor expression improves high-throughput metabolite-producer screening efficiency in yeast. Synth Biol (Oxf) 2017; 2:ysw002. [PMID: 32995501 PMCID: PMC7513737 DOI: 10.1093/synbio/ysw002] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 11/14/2016] [Accepted: 11/29/2016] [Indexed: 11/23/2022] Open
Abstract
Biosensors are valuable and versatile tools in synthetic biology that are used to modulate gene expression in response to a wide range of stimuli. Ligand responsive transcription factors are a class of biosensor that can be used to couple intracellular metabolite concentration with gene expression to enable dynamic regulation and high-throughput metabolite producer screening. We have established the Saccharomyces cerevisiae WAR1 transcriptional regulator and PDR12 promoter as an organic acid biosensor that can be used to detect varying levels of para-hydroxybenzoic acid (PHBA) production from the shikimate pathway and output green fluorescent protein (GFP) expression in response. The dynamic range of GFP expression in response to PHBA was dramatically increased by engineering positive-feedback expression of the WAR1 transcriptional regulator from its target PDR12 promoter. In addition, the noise in GFP expression at the population-level was controlled by normalising GFP fluorescence to constitutively expressed mCherry fluorescence within each cell. These biosensor modifications increased the high-throughput screening efficiency of yeast cells engineered to produce PHBA by 5,000-fold, enabling accurate fluorescence activated cell sorting isolation of producer cells that were mixed at a ratio of 1 in 10,000 with non-producers. Positive-feedback, ratiometric transcriptional regulator expression is likely applicable to many other transcription-factor/promoter pairs used in synthetic biology and metabolic engineering for both dynamic regulation and high-throughput screening applications.
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Affiliation(s)
- Thomas C Williams
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, Australia
| | - Xin Xu
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, Australia
| | - Martin Ostrowski
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, Australia
| | - Isak S Pretorius
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, Australia
| | - Ian T Paulsen
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, Australia
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27
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Genetic dissection of acetic acid tolerance in Saccharomyces cerevisiae. World J Microbiol Biotechnol 2016; 32:145. [PMID: 27430512 DOI: 10.1007/s11274-016-2101-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 06/19/2016] [Indexed: 12/24/2022]
Abstract
Dissection of the hereditary architecture underlying Saccharomyces cerevisiae tolerance to acetic acid is essential for ethanol fermentation. In this work, a genomics approach was used to dissect hereditary variations in acetic acid tolerance between two phenotypically different strains. A total of 160 segregants derived from these two strains were obtained. Phenotypic analysis indicated that the acetic acid tolerance displayed a normal distribution in these segregants, and suggested that the acetic acid tolerant traits were controlled by multiple quantitative trait loci (QTLs). Thus, 220 SSR markers covering the whole genome were used to detect QTLs of acetic acid tolerant traits. As a result, three QTLs were located on chromosomes 9, 12, and 16, respectively, which explained 38.8-65.9 % of the range of phenotypic variation. Furthermore, twelve genes of the candidates fell into the three QTL regions by integrating the QTL analysis with candidates of acetic acid tolerant genes. These results provided a novel avenue to obtain more robust strains.
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Black perithecial pigmentation in Fusarium species is due to the accumulation of 5-deoxybostrycoidin-based melanin. Sci Rep 2016; 6:26206. [PMID: 27193384 PMCID: PMC4872168 DOI: 10.1038/srep26206] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 04/26/2016] [Indexed: 11/30/2022] Open
Abstract
Biosynthesis of the black perithecial pigment in the filamentous fungus Fusarium graminearum is dependent on the polyketide synthase PGL1 (oPKS3). A seven-membered PGL1 gene cluster was identified by over-expression of the cluster specific transcription factor pglR. Targeted gene replacement showed that PGL1, pglJ, pglM and pglV were essential for the production of the perithecial pigment. Over-expression of PGL1 resulted in the production of 6-O-demethyl-5-deoxybostrycoidin (1), 5-deoxybostrycoidin (2), and three novel compounds 5-deoxybostrycoidin anthrone (3), 6-O-demethyl-5-deoxybostrycoidin anthrone (4) and purpurfusarin (5). The novel dimeric bostrycoidin purpurfusarin (5) was found to inhibit the growth of Candida albicans with an IC50 of 8.0 +/− 1.9 μM. The results show that Fusarium species with black perithecia have a previously undescribed form of 5-deoxybostrycoidin based melanin in their fruiting bodies.
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Casal M, Queirós O, Talaia G, Ribas D, Paiva S. Carboxylic Acids Plasma Membrane Transporters in Saccharomyces cerevisiae. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 892:229-251. [PMID: 26721276 DOI: 10.1007/978-3-319-25304-6_9] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
This chapter covers the functionally characterized plasma membrane carboxylic acids transporters Jen1, Ady2, Fps1 and Pdr12 in the yeast Saccharomyces cerevisiae, addressing also their homologues in other microorganisms, as filamentous fungi and bacteria. Carboxylic acids can either be transported into the cells, to be used as nutrients, or extruded in response to acid stress conditions. The secondary active transporters Jen1 and Ady2 can mediate the uptake of the anionic form of these substrates by a H(+)-symport mechanism. The undissociated form of carboxylic acids is lipid-soluble, crossing the plasma membrane by simple diffusion. Furthermore, acetic acid can also be transported by facilitated diffusion via Fps1 channel. At the cytoplasmic physiological pH, the anionic form of the acid prevails and it can be exported by the Pdr12 pump. This review will highlight the mechanisms involving carboxylic acids transporters, and the way they operate according to the yeast cell response to environmental changes, as carbon source availability, extracellular pH and acid stress conditions.
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Affiliation(s)
- Margarida Casal
- CBMA-Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal.
| | - Odília Queirós
- CBMA-Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal
- CESPU, Instituto de Investigação e Formação Avançada em Ciências e Tecnologias da Saúde, Rua Central de Gandra, 1317, 4585-116, Gandra, PRD, Portugal
| | - Gabriel Talaia
- CBMA-Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal
| | - David Ribas
- CBMA-Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal
| | - Sandra Paiva
- CBMA-Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal
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Vos T, de la Torre Cortés P, van Gulik WM, Pronk JT, Daran-Lapujade P. Growth-rate dependency of de novo resveratrol production in chemostat cultures of an engineered Saccharomyces cerevisiae strain. Microb Cell Fact 2015; 14:133. [PMID: 26369953 PMCID: PMC4570684 DOI: 10.1186/s12934-015-0321-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 08/21/2015] [Indexed: 01/28/2023] Open
Abstract
Introduction Saccharomyces cerevisiae has become a popular host for production of non-native compounds. The metabolic pathways involved generally require a net input of energy. To maximize the ATP yield on sugar in S. cerevisiae, industrial cultivation is typically performed in aerobic, sugar-limited fed-batch reactors which, due to constraints in oxygen transfer and cooling capacities, have to be operated at low specific growth rates. Because intracellular levels of key metabolites are growth-rate dependent, slow growth can significantly affect biomass-specific productivity. Using an engineered Saccharomyces cerevisiae strain expressing a heterologous pathway for resveratrol production as a model energy-requiring product, the impact of specific growth rate on yeast physiology and productivity was investigated in aerobic, glucose-limited chemostat cultures. Results Stoichiometric analysis revealed that de novo resveratrol production from glucose requires 13 moles of ATP per mole of produced resveratrol. The biomass-specific production rate of resveratrol showed a strong positive correlation with the specific growth rate. At low growth rates a substantial fraction of the carbon source was invested in cellular maintenance-energy requirements (e.g. 27 % at 0.03 h−1). This distribution of resources was unaffected by resveratrol production. Formation of the by-products coumaric, phloretic and cinnamic acid had no detectable effect on maintenance energy requirement and yeast physiology in chemostat. Expression of the heterologous pathway led to marked differences in transcript levels in the resveratrol-producing strain, including increased expression levels of genes involved in pathways for precursor supply (e.g. ARO7 and ARO9 involved in phenylalanine biosynthesis). The observed strong differential expression of many glucose-responsive genes in the resveratrol producer as compared to a congenic reference strain could be explained from higher residual glucose concentrations and higher relative growth rates in cultures of the resveratrol producer. Conclusions De novo resveratrol production by engineered S. cerevisiae is an energy demanding process. Resveratrol production by an engineered strain exhibited a strong correlation with specific growth rate. Since industrial production in fed-batch reactors typically involves low specific growth rates, this study emphasizes the need for uncoupling growth and product formation via energy-requiring pathways. Electronic supplementary material The online version of this article (doi:10.1186/s12934-015-0321-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tim Vos
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC, Delft, The Netherlands.
| | - Pilar de la Torre Cortés
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC, Delft, The Netherlands.
| | - Walter M van Gulik
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC, Delft, The Netherlands.
| | - Jack T Pronk
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC, Delft, The Netherlands.
| | - Pascale Daran-Lapujade
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC, Delft, The Netherlands.
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Glutathione is involved in physiological response of Candida utilis to acid stress. Appl Microbiol Biotechnol 2015; 99:10669-79. [DOI: 10.1007/s00253-015-6940-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 08/07/2015] [Accepted: 08/11/2015] [Indexed: 02/04/2023]
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MIG1 Regulates Resistance of Candida albicans against the Fungistatic Effect of Weak Organic Acids. EUKARYOTIC CELL 2015; 14:1054-61. [PMID: 26297702 DOI: 10.1128/ec.00129-15] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 08/13/2015] [Indexed: 12/15/2022]
Abstract
Candida albicans is the leading cause of fungal infections; but it is also a member of the human microbiome, an ecosystem of thousands of microbial species potentially influencing the outcome of host-fungal interactions. Accordingly, antibacterial therapy raises the risk of candidiasis, yet the underlying mechanism is currently not fully understood. We hypothesize the existence of bacterial metabolites that normally control C. albicans growth and of fungal resistance mechanisms against these metabolites. Among the most abundant microbiota-derived metabolites found on human mucosal surfaces are weak organic acids (WOAs), such as acetic, propionic, butyric, and lactic acid. Here, we used quantitative growth assays to investigate the dose-dependent fungistatic properties of WOAs on C. albicans growth and found inhibition of growth to occur at physiologically relevant concentrations and pH values. This effect was conserved across distantly related fungal species both inside and outside the CTG clade. We next screened a library of transcription factor mutants and identified several genes required for the resistance of C. albicans to one or more WOAs. A single gene, MIG1, previously known for its role in glucose repression, conferred resistance against all four acids tested. Consistent with glucose being an upstream activator of Mig1p, the presence of this carbon source was required for WOA resistance in wild-type C. albicans. Conversely, a MIG1-complemented strain completely restored the glucose-dependent resistance against WOAs. We conclude that Mig1p plays a central role in orchestrating a transcriptional program to fight against the fungistatic effect of this class of highly abundant metabolites produced by the gastrointestinal tract microbiota.
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Borrull A, López-Martínez G, Poblet M, Cordero-Otero R, Rozès N. New insights into the toxicity mechanism of octanoic and decanoic acids onSaccharomyces cerevisiae. Yeast 2015; 32:451-60. [DOI: 10.1002/yea.3071] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 02/26/2015] [Accepted: 03/04/2015] [Indexed: 11/08/2022] Open
Affiliation(s)
- Anna Borrull
- Dpt. Bioquímica i Biotecnología, Facultat d'Enologia; Universitat Rovira i Virgili, Campus Sescelades; Tarragona Spain
| | - Gema López-Martínez
- Dpt. Bioquímica i Biotecnología, Facultat d'Enologia; Universitat Rovira i Virgili, Campus Sescelades; Tarragona Spain
| | - Montse Poblet
- Dpt. Bioquímica i Biotecnología, Facultat d'Enologia; Universitat Rovira i Virgili, Campus Sescelades; Tarragona Spain
| | - Ricardo Cordero-Otero
- Dpt. Bioquímica i Biotecnología, Facultat d'Enologia; Universitat Rovira i Virgili, Campus Sescelades; Tarragona Spain
| | - Nicolas Rozès
- Dpt. Bioquímica i Biotecnología, Facultat d'Enologia; Universitat Rovira i Virgili, Campus Sescelades; Tarragona Spain
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Lichius A, Seidl-Seiboth V, Seiboth B, Kubicek CP. Nucleo-cytoplasmic shuttling dynamics of the transcriptional regulators XYR1 and CRE1 under conditions of cellulase and xylanase gene expression in Trichoderma reesei. Mol Microbiol 2014; 94:1162-1178. [PMID: 25302561 PMCID: PMC4282317 DOI: 10.1111/mmi.12824] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/07/2014] [Indexed: 01/26/2023]
Abstract
Trichoderma reesei is a model for investigating the regulation of (hemi-)cellulase gene expression. Cellulases are formed adaptively, and the transcriptional activator XYR1 and the carbon catabolite repressor CRE1 are main regulators of their expression. We quantified the nucleo-cytoplasmic shuttling dynamics of GFP-fusion proteins of both transcription factors under cellulase and xylanase inducing conditions, and correlated their nuclear presence/absence with transcriptional changes. We also compared their subcellular localization in conidial germlings and mature hyphae. We show that cellulase gene expression requires de novo biosynthesis of XYR1 and its simultaneous nuclear import, whereas carbon catabolite repression is regulated through preformed CRE1 imported from the cytoplasmic pool. Termination of induction immediately stopped cellulase gene transcription and was accompanied by rapid nuclear degradation of XYR1. In contrast, nuclear CRE1 rapidly decreased upon glucose depletion, and became recycled into the cytoplasm. In mature hyphae, nuclei containing activated XYR1 were concentrated in the colony center, indicating that this is the main region of XYR1 synthesis and cellulase transcription. CRE1 was found to be evenly distributed throughout the entire mycelium. Taken together, our data revealed novel aspects of the dynamic shuttling and spatial bias of the major regulator of (hemi-)cellulase gene expression, XYR1, in T. reesei.
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Affiliation(s)
- Alexander Lichius
- Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, Vienna University of TechnologyVienna, Austria
| | - Verena Seidl-Seiboth
- Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, Vienna University of TechnologyVienna, Austria
| | - Bernhard Seiboth
- Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, Vienna University of TechnologyVienna, Austria
| | - Christian P Kubicek
- Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, Vienna University of TechnologyVienna, Austria
- Austrian Center of Industrial BiotechnologyGraz, Austria
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Mojzita D, Oja M, Rintala E, Wiebe M, Penttilä M, Ruohonen L. Transcriptome of Saccharomyces cerevisiae during production of D-xylonate. BMC Genomics 2014; 15:763. [PMID: 25192596 PMCID: PMC4176587 DOI: 10.1186/1471-2164-15-763] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 08/29/2014] [Indexed: 11/24/2022] Open
Abstract
Background Production of D-xylonate by the yeast S. cerevisiae provides an example of bioprocess development for sustainable production of value-added chemicals from cheap raw materials or side streams. Production of D-xylonate may lead to considerable intracellular accumulation of D-xylonate and to loss of viability during the production process. In order to understand the physiological responses associated with D-xylonate production, we performed transcriptome analyses during D-xylonate production by a robust recombinant strain of S. cerevisiae which produces up to 50 g/L D-xylonate. Results Comparison of the transcriptomes of the D-xylonate producing and the control strain showed considerably higher expression of the genes controlled by the cell wall integrity (CWI) pathway and of some genes previously identified as up-regulated in response to other organic acids in the D-xylonate producing strain. Increased phosphorylation of Slt2 kinase in the D-xylonate producing strain also indicated that D-xylonate production caused stress to the cell wall. Surprisingly, genes encoding proteins involved in translation, ribosome structure and RNA metabolism, processes which are commonly down-regulated under conditions causing cellular stress, were up-regulated during D-xylonate production, compared to the control. The overall transcriptional responses were, therefore, very dissimilar to those previously reported as being associated with stress, including stress induced by organic acid treatment or production. Quantitative PCR analyses of selected genes supported the observations made in the transcriptomic analysis. In addition, consumption of ethanol was slower and the level of trehalose was lower in the D-xylonate producing strain, compared to the control. Conclusions The production of organic acids has a major impact on the physiology of yeast cells, but the transcriptional responses to presence or production of different acids differs considerably, being much more diverse than responses to other stresses. D-Xylonate production apparently imposed considerable stress on the cell wall. Transcriptional data also indicated that activation of the PKA pathway occurred during D-xylonate production, leaving cells unable to adapt normally to stationary phase. This, together with intracellular acidification, probably contributes to cell death. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-763) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Dominik Mojzita
- VTT Technical Research Centre of Finland, P,O, Box 1000, Espoo FI-02044 VTT, Finland.
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Yeast ABC proteins involved in multidrug resistance. Cell Mol Biol Lett 2013; 19:1-22. [PMID: 24297686 PMCID: PMC6275743 DOI: 10.2478/s11658-013-0111-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 11/27/2013] [Indexed: 01/03/2023] Open
Abstract
Pleiotropic drug resistance is a complex phenomenon that involves many proteins that together create a network. One of the common mechanisms of multidrug resistance in eukaryotic cells is the active efflux of a broad range of xenobiotics through ATP-binding cassette (ABC) transporters. Saccharomyces cerevisiae is often used as a model to study such activity because of the functional and structural similarities of its ABC transporters to mammalian ones. Numerous ABC transporters are found in humans and some are associated with the resistance of tumors to chemotherapeutics. Efflux pump modulators that change the activity of ABC proteins are the most promising candidate drugs to overcome such resistance. These modulators can be chemically synthesized or isolated from natural sources (e.g., plant alkaloids) and might also be used in the treatment of fungal infections. There are several generations of synthetic modulators that differ in specificity, toxicity and effectiveness, and are often used for other clinical effects.
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Jandric Z, Gregori C, Klopf E, Radolf M, Schüller C. Sorbic acid stress activates the Candida glabrata high osmolarity glycerol MAP kinase pathway. Front Microbiol 2013; 4:350. [PMID: 24324463 PMCID: PMC3840799 DOI: 10.3389/fmicb.2013.00350] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 11/04/2013] [Indexed: 12/27/2022] Open
Abstract
Weak organic acids such as sorbic acid are important food preservatives and powerful fungistatic agents. These compounds accumulate in the cytosol and disturb the cellular pH and energy homeostasis. Candida glabrata is in many aspects similar to Saccharomyces cerevisiae. However, with regard to confrontation to sorbic acid, two of the principal response pathways behave differently in C. glabrata. In yeast, sorbic acid stress causes activation of many genes via the transcription factors Msn2 and Msn4. The C. glabrata homologs CgMsn2 and CgMsn4 are apparently not activated by sorbic acid. In contrast, in C. glabrata the high osmolarity glycerol (HOG) pathway is activated by sorbic acid. Here we show that the MAP kinase of the HOG pathway, CgHog1, becomes phosphorylated and has a function for weak acid stress resistance. Transcript profiling of weak acid treated C. glabrata cells suggests a broad and very similar response pattern of cells lacking CgHog1 compared to wild type which is over lapping with but distinct from S. cerevisiae. The PDR12 gene was the highest induced gene in both species and it required CgHog1 for full expression. Our results support flexibility of the response cues for general stress signaling pathways, even between closely related yeasts, and functional extension of a specific response pathway.
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Affiliation(s)
- Zeljkica Jandric
- Department of Applied Genetics and Cell Biology (DAGZ), University of Natural Resources and Life Sciences Vienna, Austria
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Acid adaptation and biocontrol efficacy of antagonistic marine yeast Rhodosporidium paludigenum. ANN MICROBIOL 2013. [DOI: 10.1007/s13213-013-0681-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Zhang Y, Kweon HK, Shively C, Kumar A, Andrews PC. Towards systematic discovery of signaling networks in budding yeast filamentous growth stress response using interventional phosphorylation data. PLoS Comput Biol 2013; 9:e1003077. [PMID: 23825934 PMCID: PMC3694812 DOI: 10.1371/journal.pcbi.1003077] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 04/17/2013] [Indexed: 11/19/2022] Open
Abstract
Reversible phosphorylation is one of the major mechanisms of signal transduction, and signaling networks are critical regulators of cell growth and development. However, few of these networks have been delineated completely. Towards this end, quantitative phosphoproteomics is emerging as a useful tool enabling large-scale determination of relative phosphorylation levels. However, phosphoproteomics differs from classical proteomics by a more extensive sampling limitation due to the limited number of detectable sites per protein. Here, we propose a comprehensive quantitative analysis pipeline customized for phosphoproteome data from interventional experiments for identifying key proteins in specific pathways, discovering the protein-protein interactions and inferring the signaling network. We also made an effort to partially compensate for the missing value problem, a chronic issue for proteomics studies. The dataset used for this study was generated using SILAC (Stable Isotope Labeling with Amino acids in Cell culture) technique with interventional experiments (kinase-dead mutations). The major components of the pipeline include phosphopeptide meta-analysis, correlation network analysis and causal relationship discovery. We have successfully applied our pipeline to interventional experiments identifying phosphorylation events underlying the transition to a filamentous growth form in Saccharomyces cerevisiae. We identified 5 high-confidence proteins from meta-analysis, and 19 hub proteins from correlation analysis (Pbi2p and Hsp42p were identified by both analyses). All these proteins are involved in stress responses. Nine of them have direct or indirect evidence of involvement in filamentous growth. In addition, we tested four of our predicted proteins, Nth1p, Pbi2p, Pdr12p and Rcn2p, by interventional phenotypic experiments and all of them present differential invasive growth, providing prospective validation of our approach. This comprehensive pipeline presents a systematic way for discovering signaling networks using interventional phosphoproteome data and can suggest candidate proteins for further investigation. We anticipate the methodology to be applicable as well to other interventional studies via different experimental platforms.
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Affiliation(s)
- Yan Zhang
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Hye Kyong Kweon
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Christian Shively
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Anuj Kumar
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Philip C. Andrews
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail:
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Mutations in the basic loop of the Zn binuclear cluster of the UaY transcriptional activator suppress mutations in the dimerisation domain. Fungal Genet Biol 2012; 49:731-43. [DOI: 10.1016/j.fgb.2012.06.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 06/06/2012] [Accepted: 06/08/2012] [Indexed: 11/19/2022]
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Abstract
All fungal genomes harbour numerous ABC (ATP-binding cassette) proteins located in various cellular compartments such as the plasma membrane, vacuoles, peroxisomes and mitochondria. Most of them have initially been discovered through their ability to confer resistance to a multitude of drugs, a phenomenon called PDR (pleiotropic drug resistance) or MDR (multidrug resistance). Studying the mechanisms underlying PDR/MDR in yeast is of importance in two ways: first, ABC proteins can confer drug resistance on pathogenic fungi such as Candida spp., Aspergillus spp. or Cryptococcus neoformans; secondly, the well-established genetic, biochemical and cell biological tractability of Saccharomyces cerevisiae makes it an ideal tool to study basic mechanisms of drug transport by ABC proteins. In the past, knowledge from yeast has complemented work on human ABC transporters involved in anticancer drug resistance or genetic diseases. Interestingly, increasing evidence available from yeast and other organisms suggests that ABC proteins play a physiological role in membrane homoeostasis and lipid distribution, although this is being intensely debated in the literature.
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Molecular Mechanisms of Programmed Cell Death Induced by Acetic Acid in Saccharomyces cerevisiae. MICROBIOLOGY MONOGRAPHS 2012. [DOI: 10.1007/978-3-642-21467-7_3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Antifungal resistance and new strategies to control fungal infections. Int J Microbiol 2011; 2012:713687. [PMID: 22187560 PMCID: PMC3236459 DOI: 10.1155/2012/713687] [Citation(s) in RCA: 262] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 09/06/2011] [Indexed: 11/28/2022] Open
Abstract
Despite improvement of antifungal therapies over the last 30 years, the phenomenon of antifungal resistance is still of major concern in clinical practice. In the last 10 years the molecular mechanisms underlying this phenomenon were extensively unraveled. In this paper, after a brief overview of currently available antifungals, molecular mechanisms of antifungal resistance will be detailed. It appears that major mechanisms of resistance are essential due to the deregulation of antifungal resistance effector genes. This deregulation is a consequence of point mutations occurring in transcriptional regulators of these effector genes. Resistance can also follow the emergence of point mutations directly in the genes coding antifungal targets. In addition we further describe new strategies currently undertaken to discover alternative therapy targets and antifungals. Identification of new antifungals is essentially achieved by the screening of natural or synthetic chemical compound collections. Discovery of new putative antifungal targets is performed through genome-wide approaches for a better understanding of the human pathogenic fungi biology.
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Mollapour M, Piper PW. Activity of the yeast zinc-finger transcription factor War1 is lost with alanine mutation of two putative phosphorylation sites in the activation domain. Yeast 2011; 29:39-44. [DOI: 10.1002/yea.1915] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2011] [Accepted: 10/10/2011] [Indexed: 11/06/2022] Open
Affiliation(s)
- Mehdi Mollapour
- Department of Molecular Biology and Biotechnology; University of Sheffield; UK
| | - Peter W. Piper
- Department of Molecular Biology and Biotechnology; University of Sheffield; UK
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Semchyshyn HM, Abrat OB, Miedzobrodzki J, Inoue Y, Lushchak VI. Acetate but not propionate induces oxidative stress in bakers' yeast Saccharomyces cerevisiae. Redox Rep 2011; 16:15-23. [PMID: 21605494 DOI: 10.1179/174329211x12968219310954] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The influence of acetic and propionic acids on baker's yeast was investigated in order to expand our understanding of the effect of weak organic acid food preservatives on eukaryotic cells. Both acids decreased yeast survival in a concentration-dependent manner, but with different efficiencies. The acids inhibited the fluorescein efflux from yeast cells. The inhibition constant of fluorescein extrusion from cells treated with acetate was significantly lower in parental strain than in either PDR12 (ABC-transporter Pdr12p) or WAR1 (transcriptional factor of Pdr12p) defective mutants. The constants of inhibition by propionate were virtually the same in all strains used. Yeast exposure to acetate increased the level of oxidized proteins and the activity of antioxidant enzymes, while propionate did not change these parameters. This suggests that various mechanisms underlie the yeast toxicity by acetic and propionic acids. Our studies with mutant cells clearly indicated the involvement of Yap1p transcriptional regulator and de novo protein synthesis in superoxide dismutase up-regulation by acetate. The up-regulation of catalase was Yap1p independent. Yeast pre-incubation with low concentrations of H₂O₂ caused cellular cross-protection against high concentrations of acetate. The results are discussed from the point of view that acetate induces a prooxidant effect in vivo, whereas propionate does not.
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Affiliation(s)
- Halyna M Semchyshyn
- Department of Biochemistry and Biotechnology, Vassyl Stefanyk Precarpathian National University, Ivano-Frankivsk, Ukraine.
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Maicas S, Moreno I, Nieto A, Gómez M, Sentandreu R, Valentín E. In silico analysis for transcription factors with Zn(II)(2)C(6) binuclear cluster DNA-binding domains in Candida albicans. Comp Funct Genomics 2011; 6:345-56. [PMID: 18629206 PMCID: PMC2447501 DOI: 10.1002/cfg.492] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2005] [Revised: 05/26/2005] [Accepted: 09/05/2005] [Indexed: 11/09/2022] Open
Abstract
A total of 6047 open reading frames in the Candida albicans genome were screened for
Zn(II)2C6-type zinc cluster proteins (or binuclear cluster proteins) involved in DNA
recognition. These fungal proteins are transcription regulators of genes involved in a
wide range of cellular processes, including metabolism of different compounds such
as sugars or amino acids, as well as multi-drug resistance, control of meiosis, cell
wall architecture, etc. The selection criteria used in the sequence analysis were the
presence of the CysX2CysX6CysX5-16CysX2CysX6-8Cys motif and a putative nuclear localization signal. Using this approach, 70 putative
Zn(II)2C6 transcription factors have been found in the genome of C. albicans.
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Affiliation(s)
- Sergi Maicas
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Burjassot, Valencia 46100, Spain
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Diagnosis of Antifungal Drug Resistance Mechanisms in Fungal Pathogens: Transcriptional Gene Regulation. CURRENT FUNGAL INFECTION REPORTS 2011. [DOI: 10.1007/s12281-011-0055-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Mira NP, Henriques SF, Keller G, Teixeira MC, Matos RG, Arraiano CM, Winge DR, Sá-Correia I. Identification of a DNA-binding site for the transcription factor Haa1, required for Saccharomyces cerevisiae response to acetic acid stress. Nucleic Acids Res 2011; 39:6896-907. [PMID: 21586585 PMCID: PMC3167633 DOI: 10.1093/nar/gkr228] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The transcription factor Haa1 is the main player in reprogramming yeast genomic expression in response to acetic acid stress. Mapping of the promoter region of one of the Haa1-activated genes, TPO3, allowed the identification of an acetic acid responsive element (ACRE) to which Haa1 binds in vivo. The in silico analysis of the promoter regions of the genes of the Haa1-regulon led to the identification of an Haa1-responsive element (HRE) 5'-GNN(G/C)(A/C)(A/G)G(A/G/C)G-3'. Using surface plasmon resonance experiments and electrophoretic mobility shift assays it is demonstrated that Haa1 interacts with high affinity (K(D) of 2 nM) with the HRE motif present in the ACRE region of TPO3 promoter. No significant interaction was found between Haa1 and HRE motifs having adenine nucleotides at positions 6 and 8 (K(D) of 396 and 6780 nM, respectively) suggesting that Haa1p does not recognize these motifs in vivo. A lower affinity of Haa1 toward HRE motifs having mutations in the guanine nucleotides at position 7 and 9 (K(D) of 21 and 119 nM, respectively) was also observed. Altogether, the results obtained indicate that the minimal functional binding site of Haa1 is 5'-(G/C)(A/C)GG(G/C)G-3'. The Haa1-dependent transcriptional regulatory network active in yeast response to acetic acid stress is proposed.
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Affiliation(s)
- Nuno P Mira
- IBB, Instituto Biotecnologia e Bioengenharia, Center for Biological and Chemical Engineering, Instituto Superior Técnico, Avenida Rovisco Pais, 1049-001 Lisbon, Portugal
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Orij R, Brul S, Smits GJ. Intracellular pH is a tightly controlled signal in yeast. Biochim Biophys Acta Gen Subj 2011; 1810:933-44. [PMID: 21421024 DOI: 10.1016/j.bbagen.2011.03.011] [Citation(s) in RCA: 162] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 03/15/2011] [Accepted: 03/15/2011] [Indexed: 11/25/2022]
Abstract
BACKGROUND Nearly all processes in living cells are pH dependent, which is why intracellular pH (pH(i)) is a tightly regulated physiological parameter in all cellular systems. However, in microbes such as yeast, pH(i) responds to extracellular conditions such as the availability of nutrients. This raises the question of how pH(i) dynamics affect cellular function. SCOPE OF REVIEW We discuss the control of pH(i,) and the regulation of processes by pH(i), focusing on the model organism Saccharomyces cerevisiae. We aim to dissect the effects of pH(i) on various aspects of cell physiology, which are often intertwined. Our goal is to provide a broad overview of how pH(i) is controlled in yeast, and how pH(i) in turn controls physiology, in the context of both general cellular functioning as well as of cellular decision making upon changes in the cell's environment. MAJOR CONCLUSIONS Besides a better understanding of the regulation of pH(i), evidence for a signaling role of pH(i) is accumulating. We conclude that pH(i) responds to nutritional cues and relays this information to alter cellular make-up and physiology. The physicochemical properties of pH allow the signal to be fast, and affect multiple regulatory levels simultaneously. GENERAL SIGNIFICANCE The mechanisms for regulation of processes by pH(i) are tightly linked to the molecules that are part of all living cells, and the biophysical properties of the signal are universal amongst all living organisms, and similar types of regulation are suggested in mammals. Therefore, dynamic control of cellular decision making by pH(i) is therefore likely a general trait. This article is part of a Special Issue entitled: Systems Biology of Microorganisms.
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Affiliation(s)
- Rick Orij
- Swammerdam Institute for Life Sciences, University of Amsterdam, the Netherlands.
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