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Färkkilä SMA, Mortimer M, Jaaniso R, Kahru A, Kiisk V, Kikas A, Kozlova J, Kurvet I, Mäeorg U, Otsus M, Kasemets K. Comparison of Toxicity and Cellular Uptake of CdSe/ZnS and Carbon Quantum Dots for Molecular Tracking Using Saccharomyces cerevisiae as a Fungal Model. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 14:10. [PMID: 38202465 PMCID: PMC10781119 DOI: 10.3390/nano14010010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 12/12/2023] [Accepted: 12/15/2023] [Indexed: 01/12/2024]
Abstract
Plant resource sharing mediated by mycorrhizal fungi has been a subject of recent debate, largely owing to the limitations of previously used isotopic tracking methods. Although CdSe/ZnS quantum dots (QDs) have been successfully used for in situ tracking of essential nutrients in plant-fungal systems, the Cd-containing QDs, due to the intrinsic toxic nature of Cd, are not a viable system for larger-scale in situ studies. We synthesized amino acid-based carbon quantum dots (CQDs; average hydrodynamic size 6 ± 3 nm, zeta potential -19 ± 12 mV) and compared their toxicity and uptake with commercial CdSe/ZnS QDs that we conjugated with the amino acid cysteine (Cys) (average hydrodynamic size 308 ± 150 nm, zeta potential -65 ± 4 mV) using yeast Saccharomyces cerevisiae as a proxy for mycorrhizal fungi. We showed that the CQDs readily entered yeast cells and were non-toxic up to 100 mg/L. While the Cys-conjugated CdSe/ZnS QDs were also not toxic to yeast cells up to 100 mg/L, they were not taken up into the cells but remained on the cell surfaces. These findings suggest that CQDs may be a suitable tool for molecular tracking in fungi (incl. mychorrhizal fungi) due to their ability to enter fungal cells.
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Affiliation(s)
- Sanni M. A. Färkkilä
- Institute of Ecology and Earth Sciences, University of Tartu, Juhan Liivi 2, 50409 Tartu, Estonia
| | - Monika Mortimer
- Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia; (M.M.); (A.K.); (I.K.); (M.O.)
| | - Raivo Jaaniso
- Institute of Physics, University of Tartu, W. Ostwaldi 1, 50411 Tartu, Estonia; (R.J.); (V.K.); (A.K.); (J.K.)
| | - Anne Kahru
- Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia; (M.M.); (A.K.); (I.K.); (M.O.)
| | - Valter Kiisk
- Institute of Physics, University of Tartu, W. Ostwaldi 1, 50411 Tartu, Estonia; (R.J.); (V.K.); (A.K.); (J.K.)
| | - Arvo Kikas
- Institute of Physics, University of Tartu, W. Ostwaldi 1, 50411 Tartu, Estonia; (R.J.); (V.K.); (A.K.); (J.K.)
| | - Jekaterina Kozlova
- Institute of Physics, University of Tartu, W. Ostwaldi 1, 50411 Tartu, Estonia; (R.J.); (V.K.); (A.K.); (J.K.)
| | - Imbi Kurvet
- Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia; (M.M.); (A.K.); (I.K.); (M.O.)
| | - Uno Mäeorg
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia;
| | - Maarja Otsus
- Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia; (M.M.); (A.K.); (I.K.); (M.O.)
| | - Kaja Kasemets
- Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia; (M.M.); (A.K.); (I.K.); (M.O.)
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2
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Ciamponi FE, Procópio DP, Murad NF, Franco TT, Basso TO, Brandão MM. Multi-omics network model reveals key genes associated with p-coumaric acid stress response in an industrial yeast strain. Sci Rep 2022; 12:22466. [PMID: 36577778 PMCID: PMC9797568 DOI: 10.1038/s41598-022-26843-2] [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: 09/28/2022] [Accepted: 12/21/2022] [Indexed: 12/30/2022] Open
Abstract
The production of ethanol from lignocellulosic sources presents increasingly difficult issues for the global biofuel scenario, leading to increased production costs of current second-generation (2G) ethanol when compared to first-generation (1G) plants. Among the setbacks encountered in industrial processes, the presence of chemical inhibitors from pre-treatment processes severely hinders the potential of yeasts in producing ethanol at peak efficiency. However, some industrial yeast strains have, either naturally or artificially, higher tolerance levels to these compounds. Such is the case of S. cerevisiae SA-1, a Brazilian fuel ethanol industrial strain that has shown high resistance to inhibitors produced by the pre-treatment of cellulosic complexes. Our study focuses on the characterization of the transcriptomic and physiological impact of an inhibitor of this type, p-coumaric acid (pCA), on this strain under chemostat cultivation via RNAseq and quantitative physiological data. It was found that strain SA-1 tend to increase ethanol yield and production rate while decreasing biomass yield when exposed to pCA, in contrast to pCA-susceptible strains, which tend to decrease their ethanol yield and fermentation efficiency when exposed to this substance. This suggests increased metabolic activity linked to mitochondrial and peroxisomal processes. The transcriptomic analysis also revealed a plethora of differentially expressed genes located in co-expressed clusters that are associated with changes in biological pathways linked to biosynthetic and energetical processes. Furthermore, it was also identified 20 genes that act as interaction hubs for these clusters, while also having association with altered pathways and changes in metabolic outputs, potentially leading to the discovery of novel targets for metabolic engineering toward a more robust industrial yeast strain.
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Affiliation(s)
- F. E. Ciamponi
- grid.411087.b0000 0001 0723 2494Center for Molecular Biology and Genetic Engineering (CBMEG), State University of Campinas (Unicamp), Av. Cândido Rondon, 400, Campinas, SP 13083-875 Brazil
| | - D. P. Procópio
- grid.11899.380000 0004 1937 0722Department of Chemical Engineering, University of São Paulo (USP), Av. Prof. Luciano Gualberto, 380, São Paulo, SP 05508-010 Brazil
| | - N. F. Murad
- grid.411087.b0000 0001 0723 2494Center for Molecular Biology and Genetic Engineering (CBMEG), State University of Campinas (Unicamp), Av. Cândido Rondon, 400, Campinas, SP 13083-875 Brazil
| | - T. T. Franco
- grid.411087.b0000 0001 0723 2494School of Chemical Engineering (FEQ), State University of Campinas (Unicamp), Av. Albert Einstein, 500, Campinas, SP 13083-852 Brazil
| | - T. O. Basso
- grid.11899.380000 0004 1937 0722Department of Chemical Engineering, University of São Paulo (USP), Av. Prof. Luciano Gualberto, 380, São Paulo, SP 05508-010 Brazil
| | - M. M. Brandão
- grid.411087.b0000 0001 0723 2494Center for Molecular Biology and Genetic Engineering (CBMEG), State University of Campinas (Unicamp), Av. Cândido Rondon, 400, Campinas, SP 13083-875 Brazil
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3
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Increased volatile thiol release during beer fermentation using constructed interspecies yeast hybrids. Eur Food Res Technol 2022. [DOI: 10.1007/s00217-022-04132-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractInterspecies hybridization has been shown to be a powerful tool for developing and improving brewing yeast in a number of industry-relevant respects. Thanks to the popularity of heavily hopped ‘India Pale Ale’-style beers, there is an increased demand from brewers for strains that can boost hop aroma. Here, we explored whether hybridization could be used to construct strains with an enhanced ability to release hop-derived flavours through β-lyase activity, which releases desirable volatile thiols. Wild Saccharomyces strains were shown to possess high β-lyase activity compared to brewing strains, however, they also produced phenolic off-flavours (POF) and showed poor attenuation. To overcome these limitations, interspecies hybrids were constructed by crossing pairs of one of three brewing and one of three wild Saccharomyces strains (S. uvarum and S. eubayanus). Hybrids were screened for fermentation ability and β-lyase activity, and selected hybrids showed improved fermentation and formation of both volatile thiols (4MMP, 3MH and 3MH-acetate) and aroma-active esters compared to the parent strains. Undesirable traits (e.g. POF) could be removed from the hybrid by sporulation. To conclude, it was possible to boost the release of desirable hop-derived thiols in brewing yeast by hybridization with wild yeast. This allows production of beer with boosted hop aroma with less hops (thus improving sustainability issues).
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García-Ríos E, Guillamón JM. Genomic Adaptations of Saccharomyces Genus to Wine Niche. Microorganisms 2022; 10:microorganisms10091811. [PMID: 36144411 PMCID: PMC9500811 DOI: 10.3390/microorganisms10091811] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/05/2022] [Accepted: 09/08/2022] [Indexed: 11/16/2022] Open
Abstract
Wine yeast have been exposed to harsh conditions for millennia, which have led to adaptive evolutionary strategies. Thus, wine yeasts from Saccharomyces genus are considered an interesting and highly valuable model to study human-drive domestication processes. The rise of whole-genome sequencing technologies together with new long reads platforms has provided new understanding about the population structure and the evolution of wine yeasts. Population genomics studies have indicated domestication fingerprints in wine yeast, including nucleotide variations, chromosomal rearrangements, horizontal gene transfer or hybridization, among others. These genetic changes contribute to genetically and phenotypically distinct strains. This review will summarize and discuss recent research on evolutionary trajectories of wine yeasts, highlighting the domestication hallmarks identified in this group of yeast.
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Affiliation(s)
- Estéfani García-Ríos
- Department of Food Biotechnology, Instituto de Agroquímica y Tecnología de los Alimentos (CSIC), Avda. Agustín Escardino, 7, 46980 Paterna, Spain
- Department of Science, Universidad Internacional de Valencia-VIU, Pintor Sorolla 21, 46002 Valencia, Spain
- Correspondence:
| | - José Manuel Guillamón
- Department of Food Biotechnology, Instituto de Agroquímica y Tecnología de los Alimentos (CSIC), Avda. Agustín Escardino, 7, 46980 Paterna, Spain
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5
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Modulation of Volatile Thiol Release during Fermentation of Red Musts by Wine Yeast. Processes (Basel) 2022. [DOI: 10.3390/pr10030502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
During the alcoholic fermentation of grape sugars, wine yeast produces a range of secondary metabolites that play a critical role in the aroma profile of wines. One of the most impactful yeast-modified compound families, particularly in white wines, are the ‘fruity’ polyfunctional thiols, which include 3-mercaptohexan-1-ol (3-MH) and 4-mercapto-4-methylpentan-2-one (4-MMP). While the formation and stylistic contribution of these thiols have been extensively researched in white wines, little is known about the conditions leading to their formation in red wines. In this study, we explored the ability of yeast strains to modulate the release of these aroma compounds during the fermentation of two red musts. In laboratory-scale Pinot Noir fermentations, the formation of 3-MH strongly correlated with yeast β-lyase activity, particularly with the presence of certain genotypes of the flavour-releasing gene IRC7. Subsequent production of Grenache wine at the pilot scale, with detailed compositional and sensory analysis, was undertaken to confirm laboratory-scale observations. A commercial wine strain used for expressing ‘fruity’ thiols in Sauvignon Blanc was shown to produce wines that exhibited more intense red fruit aromas. These results reveal an opportunity for winemakers to shape red wine aroma and flavour by using yeasts that might typically be considered for white wine production.
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Ruiz J, de Celis M, Martín-Santamaría M, Benito-Vázquez I, Pontes A, Lanza VF, Sampaio JP, Santos A, Belda I. Global distribution of IRC7 alleles in Saccharomyces cerevisiae populations: a genomic and phenotypic survey within the wine clade. Environ Microbiol 2021; 23:3182-3195. [PMID: 33973343 DOI: 10.1111/1462-2920.15540] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 03/23/2021] [Accepted: 04/19/2021] [Indexed: 11/28/2022]
Abstract
The adaptation to the different biotic and abiotic factors of wine fermentation has led to the accumulation of numerous genomic hallmarks in Saccharomyces cerevisiae wine strains. IRC7, a gene encoding a cysteine-S-β-lyase enzyme related volatile thiols production in wines, has two alleles: a full-length allele (IRC7F ) and a mutated one (IRC7S ), harbouring a 38 bp-deletion. Interestingly, IRC7S -encoding a less active enzyme - appears widespread amongst wine populations. Studying the global distribution of the IRC7S allele in different yeast lineages, we confirmed its high prevalence in the Wine clade and demonstrated a minority presence in other domesticated clades (Wine-PDM, Beer and Bread) while it is completely missing in wild clades. Here, we show that IRC7S -homozygous (HS) strains exhibited both fitness and competitive advantages compared with IRC7F -homozygous (HF) strains. There are some pieces of evidence of the direct contribution of the IRC7S allele to the outstanding behaviour of HS strains (i.e., improved response to oxidative stress conditions and higher tolerance to high copper levels); however, we also identified a set of sequence variants with significant co-occurrence patterns with the IRC7S allele, which can be co-contributing to the fitness and competitive advantages of HS strains in wine fermentations.
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Affiliation(s)
- Javier Ruiz
- Department of Genetics, Physiology and Microbiology. Unit of Microbiology. Biology Faculty, Complutense University of Madrid, Madrid, 28040, Spain
| | - Miguel de Celis
- Department of Genetics, Physiology and Microbiology. Unit of Microbiology. Biology Faculty, Complutense University of Madrid, Madrid, 28040, Spain
| | - María Martín-Santamaría
- Department of Genetics, Physiology and Microbiology. Unit of Microbiology. Biology Faculty, Complutense University of Madrid, Madrid, 28040, Spain
| | - Iván Benito-Vázquez
- Department of Genetics, Physiology and Microbiology. Unit of Microbiology. Biology Faculty, Complutense University of Madrid, Madrid, 28040, Spain
| | - Ana Pontes
- Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, 2829-516, Portugal
| | - Val F Lanza
- Department of Microbiology, Ramón y Cajal University Hospital, IRYCIS, Madrid, 28034, Spain
| | - José Paulo Sampaio
- Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, 2829-516, Portugal
| | - Antonio Santos
- Department of Genetics, Physiology and Microbiology. Unit of Microbiology. Biology Faculty, Complutense University of Madrid, Madrid, 28040, Spain
| | - Ignacio Belda
- Department of Genetics, Physiology and Microbiology. Unit of Microbiology. Biology Faculty, Complutense University of Madrid, Madrid, 28040, Spain
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7
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Deed RC, Hou R, Kinzurik MI, Gardner RC, Fedrizzi B. The role of yeast ARO8, ARO9 and ARO10 genes in the biosynthesis of 3-(methylthio)-1-propanol from L-methionine during fermentation in synthetic grape medium. FEMS Yeast Res 2019; 19:5113456. [PMID: 30277518 DOI: 10.1093/femsyr/foy109] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 09/30/2018] [Indexed: 11/14/2022] Open
Abstract
3-(methylthio)-1-propanol (methionol), produced by yeast as an end-product of L-methionine (L-Met) catabolism, imparts off-odours reminiscent of cauliflower and potato to wine. Saccharomyces cerevisiae ARO genes, including transaminases Aro8p and Aro9p, and decarboxylase Aro10p, catalyse two key steps forming methionol via the Ehrlich pathway. We compared methionol concentrations in wines fermented by single Δaro8, Δaro9 and Δaro10 deletants in lab strain BY4743 versus wine strain Zymaflore F15, and F15 double- and triple-aro deletants versus single-aro deletants, using headspace-solid phase microextraction coupled with gas chromatography-mass spectrometry.Deletion of two or more aro genes increased growth lag phase, with the greatest delay exhibited by F15 Δaro8 Δaro9. The single Δaro8 deletion decreased methionol by 44% in BY4743 and 92% in F15, while the Δaro9 deletion increased methionol by 46% in F15 but not BY4743. Single deletion of Δaro10 had no effect on methionol.Unexpectedly, F15 Δaro8 Δaro9 and F15 Δaro8 Δaro9 Δaro10 produced more methionol than F15 Δaro8. In the absence of Aro8p and Aro9p, other transaminases may compensate or an alternative pathway may convert methanethiol to methionol. Our results confirm that Ehrlich pathway genes differ greatly between lab and wine yeast strains, impacting downstream products such as methionol.
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Affiliation(s)
- Rebecca C Deed
- School of Chemical Sciences, University of Auckland, 32 Symonds St, Auckland 1142, New Zealand.,School of Biological Sciences, University of Auckland, 3A Symonds Street, Auckland 1142, New Zealand
| | - Ruoyu Hou
- School of Chemical Sciences, University of Auckland, 32 Symonds St, Auckland 1142, New Zealand
| | - Matias I Kinzurik
- School of Chemical Sciences, University of Auckland, 32 Symonds St, Auckland 1142, New Zealand.,New Zealand Winegrowers, 52 Symonds St, Auckland 1010, New Zealand
| | - Richard C Gardner
- School of Biological Sciences, University of Auckland, 3A Symonds Street, Auckland 1142, New Zealand
| | - Bruno Fedrizzi
- School of Chemical Sciences, University of Auckland, 32 Symonds St, Auckland 1142, New Zealand
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8
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Inactivating Mutations in Irc7p Are Common in Wine Yeasts, Attenuating Carbon-Sulfur β-Lyase Activity and Volatile Sulfur Compound Production. Appl Environ Microbiol 2019; 85:AEM.02684-18. [PMID: 30658969 DOI: 10.1128/aem.02684-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 01/11/2019] [Indexed: 01/19/2023] Open
Abstract
During alcoholic fermentation of grape sugars, wine yeasts produce a range of secondary metabolites that play an important role in the aroma profile of wines. In this study, we have explored the ability of a large number of wine yeast strains to modulate wine aroma composition, focusing on the release of the "fruity" thiols 3-mercaptohexan-1-ol (3-MH) and 4-mercapto-4-methylpentan-2-one (4-MMP) from their respective cysteinylated nonvolatile precursors. The role of the yeast gene IRC7 in thiol release has been well established, and it has been shown that a 38-bp deletion found in many wine strains cause them to express a truncated version of Irc7p that does not possess cysteine-S-conjugate β-lyase activity. In our data, we find that IRC7 allele length alone does not fully explain the capacity of a strain to release thiols. Screening of a large number of strains coupled with analysis of genomic sequence data allowed us to identify several previously undescribed single-nucleotide polymorphisms (SNPs) in IRC7 that, when coupled with allele length, more robustly explain the ability of a particular yeast strain to release thiols from their cysteinylated precursors. We also demonstrate that allelic variation of IRC7 not only affects the release of thiols but modulates the formation of negative volatile sulfur compounds from the amino acid cysteine. The results of this study provide winemakers with an improved understanding of the genetic determinants that affect wine aroma and flavor, which can be used to guide the choice of yeast strains that are fit for purpose.IMPORTANCE Volatile sulfur compounds contribute to wine aromas that may be considered pleasant, such as "tropical," "passionfruit," and "guava," as well as aromas that are considered undesirable, such as "rotten eggs," "onions," and "sewer." During fermentation, wine yeasts release some of these compounds from odorless precursor molecules, a process that is most efficient when performed by yeasts that express active forms of the protein Irc7p. We show that most wine yeasts carry mutations that reduce activity of this protein, affecting the formation of volatile sulfur compounds that impart both pleasant and unpleasant aromas. The results provide winemakers with guidance on the choice of yeasts that can emphasize or deemphasize this particular contribution to wine quality.
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9
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Pilkington LI, Deed RC, Parish-Virtue K, Huang CW, Walker ME, Jiranek V, Barker D, Fedrizzi B. Iterative synthetic strategies and gene deletant experiments enable the first identification of polysulfides in Saccharomyces cerevisiae. Chem Commun (Camb) 2019; 55:8868-8871. [DOI: 10.1039/c9cc03020d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Polysulfides, potential signalling molecules, were synthesised and then found and explored for the first time in yeast.
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Affiliation(s)
- Lisa I. Pilkington
- School of Chemical Sciences
- The University of Auckland
- Auckland 1142
- New Zealand
| | - Rebecca C. Deed
- School of Chemical Sciences
- The University of Auckland
- Auckland 1142
- New Zealand
- School of Biological Sciences
| | - Katie Parish-Virtue
- School of Chemical Sciences
- The University of Auckland
- Auckland 1142
- New Zealand
| | - Chien-Wei Huang
- School of Chemical Sciences
- The University of Auckland
- Auckland 1142
- New Zealand
| | - Michelle E. Walker
- Department of Wine and Food Science
- The University of Adelaide
- Wine Innovation Central
- Adelaide
- Australia
| | - Vladimir Jiranek
- Department of Wine and Food Science
- The University of Adelaide
- Wine Innovation Central
- Adelaide
- Australia
| | - David Barker
- School of Chemical Sciences
- The University of Auckland
- Auckland 1142
- New Zealand
| | - Bruno Fedrizzi
- School of Chemical Sciences
- The University of Auckland
- Auckland 1142
- New Zealand
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10
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Novel biosynthetic pathway for sulfur amino acids in Cryptococcus neoformans. Curr Genet 2017; 64:681-696. [PMID: 29159425 DOI: 10.1007/s00294-017-0783-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/01/2017] [Accepted: 11/16/2017] [Indexed: 12/27/2022]
Abstract
We elucidated a unique feature of sulfur metabolism in Cryptococcus neoformans. C. neoformans produces cysteine solely by the O-acetylserine pathway that consists of serine-O-acetyl transferase and cysteine synthase. We designated the gene encoding the former enzyme CYS2 (locus tag CNE02740) and the latter enzyme CYS1 (locus tag CNL05880). The cys1Δmutant strain was found to be avirulent in a murine infection model. Methionine practically does not support growth of the cys1Δ strain, and cysteine does not serve as a methionine source, indicating that the transsulfuration pathway does not contribute to sulfur amino acid synthesis in C. neoformans. Among the genes encoding enzymes catalyzing the reactions from homoserine to methionine, the gene corresponding to the Saccharomyces cerevisiae MET17 encoding O-acetylhomoserine sulfhydrylase (Met17p) had remained to be identified in C. neoformans. By genetic analysis of Met- mutants obtained by Agrobacterium tumefaciens-mediated mutagenesis, we concluded that Cnc01220, most similar to Str2p (36% identity), cystathionine-γ-synthase, in the Saccharomyces genome, is the C. neoformans version of O-acetylhomoserine sulfhydrylase. We designated CNC01220 as MET17. The C. neoformans met3Δ mutant defective in the first step of the sulfate assimilation pathway, sulfate adenylyltransferase, barely uses methionine as a sulfur source, whereas it uses cysteine efficiently. The poor utilization of methionine by the met3Δ mutant is most probably due to the absence of the transsulfuration pathway, causing an incapability of C. neoformans to produce cysteine and hydrogen sulfide from methionine. When cysteine is used as a sulfur source, methionine is likely produced de novo by using hydrogen sulfide derived from cysteine via an unidentified pathway. Altogether, the unique features of sulfur amino acid metabolism in C. neoformans will make this fungus a valuable experimental system to develop anti-fungal agents and to investigate physiology of hydrogen sulfide.
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11
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Huang CW, Walker ME, Fedrizzi B, Gardner RC, Jiranek V. Yeast genes involved in regulating cysteine uptake affect production of hydrogen sulfide from cysteine during fermentation. FEMS Yeast Res 2017; 17:3934655. [PMID: 28810701 DOI: 10.1093/femsyr/fox046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 07/04/2017] [Indexed: 11/13/2022] Open
Abstract
An early burst of hydrogen sulfide (H2S) produced by Saccharomyces cerevisiae during fermentation could increase varietal thiols and therefore enhance desirable tropical aromas in varieties such as Sauvignon Blanc. Here we attempted to identify genes affecting H2S formation from cysteine by screening yeast deletion libraries via a colony colour assay on media resembling grape juice. Both Δlst4 and Δlst7 formed lighter coloured colonies and produced significantly less H2S than the wild type on high concentrations of cysteine, likely because they are unable to take up cysteine efficiently. We then examined the nine known cysteine permeases and found that deletion of AGP1, GNP1 and MUP1 led to reduced production of H2S from cysteine. We further showed that deleting genes involved in the SPS-sensing pathway such as STP1 and DAL81 also reduced H2S from cysteine. Together, this study indirectly confirms that Agp1p, Gnp1p and Mup1p are the major cysteine permeases and that they are regulated by the SPS-sensing and target of rapamycin pathways under the grape juice-like, cysteine-supplemented, fermentation conditions. The findings highlight that cysteine transportation could be a limiting factor for yeast to generate H2S from cysteine, and therefore selecting wine yeasts without defects in cysteine uptake could maximise thiol production potential.
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Affiliation(s)
- Chien-Wei Huang
- Department of Wine and Food Science, University of Adelaide, Adelaide, SA 5064, Australia
| | - Michelle E Walker
- Department of Wine and Food Science, University of Adelaide, Adelaide, SA 5064, Australia
| | - Bruno Fedrizzi
- Wine Science Programme, School of Chemical Sciences, University of Auckland, Auckland 1142, New Zealand
| | - Richard C Gardner
- Wine Science Programme, School of Biological Sciences, University of Auckland, Auckland 1142, New Zealand
| | - Vladimir Jiranek
- Department of Wine and Food Science, University of Adelaide, Adelaide, SA 5064, Australia
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12
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Huang CW, Walker ME, Fedrizzi B, Gardner RC, Jiranek V. Hydrogen sulfide and its roles in Saccharomyces cerevisiae in a winemaking context. FEMS Yeast Res 2017; 17:4056150. [DOI: 10.1093/femsyr/fox058] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 07/28/2017] [Indexed: 01/02/2023] Open
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13
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Bae NS, Seberg AP, Carroll LP, Swanson MJ. Identification of Genes in Saccharomyces cerevisiae that Are Haploinsufficient for Overcoming Amino Acid Starvation. G3 (BETHESDA, MD.) 2017; 7:1061-1084. [PMID: 28209762 PMCID: PMC5386856 DOI: 10.1534/g3.116.037416] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 02/11/2017] [Indexed: 12/17/2022]
Abstract
The yeast Saccharomyces cerevisiae responds to amino acid deprivation by activating a pathway conserved in eukaryotes to overcome the starvation stress. We have screened the entire yeast heterozygous deletion collection to identify strains haploinsufficient for growth in the presence of sulfometuron methyl, which causes starvation for isoleucine and valine. We have discovered that cells devoid of MET15 are sensitive to sulfometuron methyl, and loss of heterozygosity at the MET15 locus can complicate screening the heterozygous deletion collection. We identified 138 cases of loss of heterozygosity in this screen. After eliminating the issues of the MET15 loss of heterozygosity, strains isolated from the collection were retested on sulfometuron methyl. To determine the general effect of the mutations for a starvation response, SMM-sensitive strains were tested for the ability to grow in the presence of canavanine, which induces arginine starvation, and strains that were MET15 were also tested for growth in the presence of ethionine, which causes methionine starvation. Many of the genes identified in our study were not previously identified as starvation-responsive genes, including a number of essential genes that are not easily screened in a systematic way. The genes identified span a broad range of biological functions, including many involved in some level of gene expression. Several unnamed proteins have also been identified, giving a clue as to possible functions of the encoded proteins.
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Affiliation(s)
- Nancy S Bae
- Department of Biochemistry, Arizona College of Osteopathic Medicine, Midwestern University, Glendale, Arizona 85308
| | - Andrew P Seberg
- Department of Biological Science, Florida State University, Tallahassee, Florida 32306-4295
| | - Leslie P Carroll
- Division of Basic Medical Sciences, Mercer University School of Medicine, Macon, Georgia 31207
| | - Mark J Swanson
- Department of Biochemistry, Arizona College of Osteopathic Medicine, Midwestern University, Glendale, Arizona 85308
- Division of Basic Medical Sciences, Mercer University School of Medicine, Macon, Georgia 31207
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14
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The yeast TUM1 affects production of hydrogen sulfide from cysteine treatment during fermentation. FEMS Yeast Res 2016; 16:fow100. [DOI: 10.1093/femsyr/fow100] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 09/04/2016] [Accepted: 11/24/2016] [Indexed: 01/05/2023] Open
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15
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Improvement of aromatic thiol release through the selection of yeasts with increased β-lyase activity. Int J Food Microbiol 2016; 225:1-8. [PMID: 26971012 DOI: 10.1016/j.ijfoodmicro.2016.03.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Revised: 01/22/2016] [Accepted: 03/01/2016] [Indexed: 11/23/2022]
Abstract
The development of a selective medium for the rapid differentiation of yeast species with increased aromatic thiol release activity has been achieved. The selective medium was based on the addition of S-methyl-l-cysteine (SMC) as β-lyase substrate. In this study, a panel of 245 strains of Saccharomyces cerevisiae strains was tested for their ability to grow on YCB-SMC medium. Yeast strains with an increased β-lyase activity grew rapidly because of their ability to release ammonium from SMC in comparison to others, and allowed for the easy isolation and differentiation of yeasts with promising properties in oenology, or another field, for aromatic thiol release. The selective medium was also helpful for the discrimination between those S. cerevisiae strains, which present a common 38-bp deletion in the IRC7 sequence (present in around 88% of the wild strains tested and are likely to be less functional for 4-mercapto-4-methylpentan-2-one (4MMP) production), and those S. cerevisiae strains homozygous for the full-length IRC7 allele. The medium was also helpful for the selection of non-Saccharomyces yeasts with increased β-lyase activity. Based on the same medium, a highly sensitive, reproducible and non-expensive GC-MS method for the evaluation of the potential volatile thiol release by different yeast isolates was developed.
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16
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Santiago M, Gardner RC. Yeast genes required for conversion of grape precursors to varietal thiols in wine. FEMS Yeast Res 2015; 15:fov034. [PMID: 26038341 DOI: 10.1093/femsyr/fov034] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 05/29/2015] [Indexed: 11/13/2022] Open
Abstract
Three varietal thiols are important for the tropical fruit aromas of Sauvignon blanc: 4-mercapto-4-methylpentan-2-one (4MMP), 3-mercaptohexanol (3MH) and its acetylated derivative 3-mercaptohexyl acetate (3MHA). These thiols are produced by yeast during fermentation from precursors in grape juice. Here we identify genes in Saccharomyces cerevisiae that are required for the transport and cleavage of two thiol precursors: cysteine-4MMP and glutathione-3MH. A full-length copy of IRC7 is absolutely required for the cleavage of both precursors in the tested strains; the deleted form of the enzyme found in most yeast strains is incapable of converting these compounds into detectable thiols. By using strains that overexpress full-length IRC7, we further show that the glutathione transporter OPT1 and the transpeptidase CIS2 are also required for conversion of glut-3MH to its varietal thiol. No transporter for cys-4MMP was identified: a strain deleted for all nine known cysteine transport genes was still capable of converting cys-4MMP to its varietal thiol, and was also able to take up cysteine at high concentrations. Based on these results, we conclude that cysteine and glutathione precursors make a relatively minor contribution to 3MH production from most grape juices.
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Affiliation(s)
- Margarita Santiago
- Wine Science Programme, School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1010, New Zealand
| | - Richard C Gardner
- Wine Science Programme, School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1010, New Zealand
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