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Escaping from the Cutoff Paradox by Accumulating Long-Chain Alcohols in the Cell Membrane. J Med Chem 2022; 65:10471-10480. [PMID: 35857416 DOI: 10.1021/acs.jmedchem.2c00629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mechanism for the cutoff, an activity cliff at which long-chain alcohols lose their biological effects, has not been elucidated. Highly hydrophobic oleyl alcohol (C18:1) exists as a mixture of monomers and aggregated droplets in water. C18:1 did not inhibit the yeast growth but inhibited the growth of the slime mold without a cell wall. C18:1 exhibited toxicity to the yeast protoplast, which was enhanced by polyethylene glycol, a fusogen. Therefore, direct interactions of C18:1 with the membrane are crucial for the toxicity. The cutoff alcohols, C14 and C16, also exhibited strong toxicity obeying the Meyer-Overton correlation, in intact yeast cells whose membrane growth was suppressed in water. Taken together, the cutoff is avoidable by securing sufficient accumulation of the wall-permeable monomers in the membrane, which supports the lipid theory. It would be important to distinguish the effective drug structure localizing in the membrane and deal with the amount in the membrane.
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Technology used to build and transfer mammalian chromosomes. Exp Cell Res 2020; 388:111851. [PMID: 31952951 DOI: 10.1016/j.yexcr.2020.111851] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 01/09/2020] [Accepted: 01/14/2020] [Indexed: 01/05/2023]
Abstract
In the near twenty-year existence of the human and mammalian artificial chromosome field, the technologies for artificial chromosome construction and installation into desired cell types or organisms have evolved with the rest of modern molecular and synthetic biology. Medical, industrial, pharmaceutical, agricultural, and basic research scientists seek the as yet unrealized promise of human and mammalian artificial chromosomes. Existing technologies for both top-down and bottom-up approaches to construct these artificial chromosomes for use in higher eukaryotes are very different but aspire to achieve similar results. New capacity for production of chromosome sized synthetic DNA will likely shift the field towards more bottom-up approaches, but not completely. Similarly, new approaches to install human and mammalian artificial chromosomes in target cells will compete with the microcell mediated cell transfer methods that currently dominate the field.
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Abstract
SCRaMbLE (Synthetic Chromosome Rearrangement and Modification by LoxP-mediated Evolution) is a genome restructuring technique that can be used in synthetic genomes such as that of Sc2.0, the synthetic yeast genome, which contains hundreds to thousands of strategically positioned loxPsym sites. SCRaMbLE has been used to induce rearrangements in yeast strains harboring one or more synthetic chromosomes, as well as plasmid DNA in vitro and in vivo. Here we describe a collection of heterozygous diploid strains produced by mating haploid semisynthetic Sc2.0 strains to haploid native parental strains. We subsequently demonstrate that such heterozygous diploid strains are more robust to the effects of SCRaMbLE than haploid semisynthetic strains, rapidly improve rationally selected phenotypes in SCRaMbLEd heterozygous diploids, and establish that multiple sets of independent genomic rearrangements are able to lead to similar phenotype enhancements. Finally, we show that heterozygous diploid SCRaMbLE can also be carried out in interspecies hybrid strains. SCRaMbLE has been used to rearrange synthetic chromosomes that have been introduced into host yeast. Here the authors produce semi-synthetic heterozygous diploid strains for rapid selection of phenotypes and map the rearrangements underlying selected phenotypes such as thermoresistance and caffeine resistance.
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Construction of Dextrin Fermentative Yeast Strains That Do Not Produce Phenolic Off-Flavors in Beer. JOURNAL OF THE AMERICAN SOCIETY OF BREWING CHEMISTS 2018. [DOI: 10.1094/asbcj-41-0045] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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5
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Some Molecular Structures in the Genome of Lager Brewing Yeasts. JOURNAL OF THE AMERICAN SOCIETY OF BREWING CHEMISTS 2018. [DOI: 10.1094/asbcj-42-0001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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6
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Use of Spheroplast Fusion and Genetic Transformation to Introduce Dextrin Utilization intoSaccharomyces Uvarum. JOURNAL OF THE AMERICAN SOCIETY OF BREWING CHEMISTS 2018. [DOI: 10.1094/asbcj-38-0001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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7
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Electrophoretic Banding Patterns of Chromosomal DNA from Yeasts. JOURNAL OF THE AMERICAN SOCIETY OF BREWING CHEMISTS 2018. [DOI: 10.1094/asbcj-47-0109] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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8
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Application of Yeast Genetics within the Brewing Industry. A Review. JOURNAL OF THE AMERICAN SOCIETY OF BREWING CHEMISTS 2018. [DOI: 10.1094/asbcj-36-0175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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9
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Breeding of a Brewer's Yeast Possessing Anticontaminant Properties. JOURNAL OF THE AMERICAN SOCIETY OF BREWING CHEMISTS 2018. [DOI: 10.1094/asbcj-42-0164] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Fusion ofSaccharomyces UvarumwithSaccharomyces Cerevisiae:Genetic Manipulation and Reconstruction of a Brewer's Yeast. JOURNAL OF THE AMERICAN SOCIETY OF BREWING CHEMISTS 2018. [DOI: 10.1094/asbcj-38-0049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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11
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In Saccharomyces cerevisiae gene targeting fidelity depends on a transformation method and proportion of the overall length of the transforming and targeted DNA. FEMS Yeast Res 2017. [DOI: 10.1093/femsyr/fox041] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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12
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Novel brewing yeast hybrids: creation and application. Appl Microbiol Biotechnol 2016; 101:65-78. [PMID: 27885413 PMCID: PMC5203825 DOI: 10.1007/s00253-016-8007-5] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 11/09/2016] [Accepted: 11/11/2016] [Indexed: 11/29/2022]
Abstract
The natural interspecies Saccharomyces cerevisiae × Saccharomyces eubayanus hybrid yeast is responsible for global lager beer production and is one of the most important industrial microorganisms. Its success in the lager brewing environment is due to a combination of traits not commonly found in pure yeast species, principally low-temperature tolerance, and maltotriose utilization. Parental transgression is typical of hybrid organisms and has been exploited previously for, e.g., the production of wine yeast with beneficial properties. The parental strain S. eubayanus has only been discovered recently and newly created lager yeast strains have not yet been applied industrially. A number of reports attest to the feasibility of this approach and artificially created hybrids are likely to have a significant impact on the future of lager brewing. De novo S. cerevisiae × S. eubayanus hybrids outperform their parent strains in a number of respects, including, but not restricted to, fermentation rate, sugar utilization, stress tolerance, and aroma formation. Hybrid genome function and stability, as well as different techniques for generating hybrids and their relative merits are discussed. Hybridization not only offers the possibility of generating novel non-GM brewing yeast strains with unique properties, but is expected to aid in unraveling the complex evolutionary history of industrial lager yeast.
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Transferring whole genomes from bacteria to yeast spheroplasts using entire bacterial cells to reduce DNA shearing. Nat Protoc 2014; 9:743-50. [PMID: 24603933 DOI: 10.1038/nprot.2014.045] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Direct cell-to-cell transfer of genomes from bacteria to yeast facilitates genome engineering for bacteria that are not amenable to genetic manipulation by allowing instead for the utilization of the powerful yeast genetic tools. Here we describe a protocol for transferring whole genomes from bacterial cells to yeast spheroplasts without any DNA purification process. The method is dependent on the treatment of the bacterial and yeast cellular mixture with PEG, which induces cell fusion, engulfment, aggregation or lysis. Over 80% of the bacterial genomes transferred in this way are complete, on the basis of structural and functional tests. Excluding the time required for preparing starting cultures and for incubating cells to form final colonies, the protocol can be completed in 3 h.
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Protoplast fusion in a petite-negative yeast, Kluyveromyces lactis. Curr Genet 2013; 2:87-93. [PMID: 24189728 DOI: 10.1007/bf00445699] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/1980] [Indexed: 11/28/2022]
Abstract
The technique of protoplast fusion has been applied to the problem of unstable diploidy in the yeast Kluyveromyces lactis. By protoplast fusion between heterothallic strains of like mating-type, sporulation-deficient hybrids can be obtained. Biochemical, cytological, and genetical characterisation of these hybrids suggests that the majority of fusion products are diploid. Sporulating hybrids can be constructed by protoplast fusion between homothallic strains. Tetrad analysis of these hybrids demonstrates conclusively the diploid nature of fusion products.
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Hybridization of Saccharomyces cerevisiae with Candida utilis through protoplast fusion. Curr Genet 2013; 8:575-80. [PMID: 24177996 DOI: 10.1007/bf00395702] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/1984] [Indexed: 10/26/2022]
Abstract
Auxotrophic mutants of Saccharomyces cerevisiae and Candida utilis were hybridized through protoplast fusion. Spontaneous, UV- and FPA-induced mitotic segregation indicated that after cell fusion, exclusion of the S. cerevisiae nucleus or nuclear fusion followed by preferential loss of S. cerevisiae chromosomes can take place. Some of the hybrids were stable. One of them, expressed mating and sporulation functions of the S. cerevisiae parent. Thus, markers from both parents could be recovered as mitotic and meiotic segregants.
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Abstract
Data presented here demonstrate that fusion of protoplasts of two different haploid strains of Saccharomyces cerevisiae having the same mating type leads to the formation of "fusants" and "cytoplasmic hybrids". The nuclear and cytoplasmic genome of a "fusant" combine those of the parent haploid strains. The "cytoplasmic hybrid" possesses the haploid genome of one parent and the combined cytoplasmic genomes of both. In mouse cells lines such products have been termed "cybrids" and this term has therefore been adopted here (Bunn and Wallace 1974).
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TRANSFORMATION OF MALTOTRIOSE UPTAKE ABILITY INTO A HAPLOID STRAIN OFSACCHAROMYCESSPP.*. JOURNAL OF THE INSTITUTE OF BREWING 2013. [DOI: 10.1002/j.2050-0416.1980.tb03957.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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20
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CURRENT DEVELOPMENTS IN THE GENETIC MANIPULATION OF BREWING YEAST STRAINS-A REVIEW*. JOURNAL OF THE INSTITUTE OF BREWING 2013. [DOI: 10.1002/j.2050-0416.1983.tb04163.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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ONE HUNDRED YEARS OF YEAST RESEARCH AND DEVELOPMENT IN THE BREWING INDUSTRY. JOURNAL OF THE INSTITUTE OF BREWING 2013. [DOI: 10.1002/j.2050-0416.1986.tb04453.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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23
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Direct transfer of whole genomes from bacteria to yeast. Nat Methods 2013; 10:410-2. [PMID: 23542886 DOI: 10.1038/nmeth.2433] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 03/08/2013] [Indexed: 11/08/2022]
Abstract
Transfer of genomes into yeast facilitates genome engineering for genetically intractable organisms, but this process has been hampered by the need for cumbersome isolation of intact genomes before transfer. Here we demonstrate direct cell-to-cell transfer of bacterial genomes as large as 1.8 megabases (Mb) into yeast under conditions that promote cell fusion. Moreover, we discovered that removal of restriction endonucleases from donor bacteria resulted in the enhancement of genome transfer.
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24
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Yeast competence for exogenous DNA uptake: towards understanding its genetic component. Antonie van Leeuwenhoek 2013; 103:1181-207. [DOI: 10.1007/s10482-013-9905-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 03/14/2013] [Indexed: 12/20/2022]
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25
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Abstract
Forced interspecific hybridization has been used in yeasts for many years to study speciation or to construct artificial strains with novel fermentative and metabolic properties. Recent genome analyses indicate that natural hybrids are also generated spontaneously between yeasts belonging to distinct species, creating lineages with novel phenotypes, varied genetic stability, or altered virulence in the case of pathogens. Large segmental introgressions from evolutionarily distant species are also visible in some yeast genomes, suggesting that interspecific genetic exchanges occur during evolution. The origin of this phenomenon remains unclear, but it is likely based on weak prezygotic barriers, limited Dobzhansky-Muller (DM) incompatibilities, and rapid clonal expansions. Newly formed interspecies hybrids suffer rapid changes in the genetic contribution of each parent, including chromosome loss or aneuploidy, translocations, and loss of heterozygosity, that, except in a few recently studied cases, remain to be characterized more precisely at the genomic level by use of modern technologies. We review here known cases of natural or artificially formed interspecies hybrids between yeasts and discuss their potential importance in terms of genome evolution. Problems of meiotic fertility, ploidy constraint, gene and gene product compatibility, and nucleomitochondrial interactions are discussed and placed in the context of other known mechanisms of yeast genome evolution as a model for eukaryotes.
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Construction of lactose-assimilating and high-ethanol-producing yeasts by protoplast fusion. Appl Environ Microbiol 2010; 51:362-7. [PMID: 16346992 PMCID: PMC238874 DOI: 10.1128/aem.51.2.362-367.1986] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The availability of a yeast strain which is capable of fermenting lactose and at the same time is tolerant to high concentrations of ethanol would be useful for the production of ethanol from lactose. Kluyveromyces fragilis is capable of fermenting lactose, but it is not as tolerant as Saccharomyces cerevisiae to high concentrations of ethanol. In this study, we have used the protoplast fusion technique to construct hybrids between auxotrophic strains of S. cerevisiae having high ethanol tolerance and an auxotrophic strain of lactose-fermenting K. fragilis isolated by ethyl methanesulfonate mutagenesis. The fusants obtained were prototrophic and capable of assimilating lactose and producing ethanol in excess of 13% (vol/vol). The complementation frequency of fusion was about 0.7%. Formation of fusants was confirmed by the increased amount of chromosomal DNA per cell. Fusants contained 8 x 10 to 16 x 10 mug of DNA per cell as compared with about 4 x 10 mug of DNA per cell for the parental strains, suggesting that multiple fusions had taken place.
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Construction of killer industrial yeast Saccharomyces cerevisiae hau-1 and its fermentation performance. Braz J Microbiol 2010; 41:477-85. [PMID: 24031519 PMCID: PMC3768693 DOI: 10.1590/s1517-838220100002000030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2008] [Revised: 04/10/2009] [Accepted: 11/08/2009] [Indexed: 11/21/2022] Open
Abstract
Saccharomyces cerevisiae HAU-1, a time tested industrial yeast possesses most of the desirable fermentation characteristics like fast growth and fermentation rate, osmotolerance, high ethanol tolerance, ability to ferment molasses, and to ferment at elevated temperatures etc. However, this yeast was found to be sensitive against the killer strains of Saccharomyces cerevisiae. In the present study, killer trait was introduced into Saccharomyces cerevisiae HAU-1 by protoplast fusion with Saccharomyces cerevisiae MTCC 475, a killer strain. The resultant fusants were characterized for desirable fermentation characteristics. All the technologically important characteristics of distillery yeast Saccharomyces cerevisiae HAU-1 were retained in the fusants, and in addition the killer trait was also introduced into them. Further, the killer activity was found to be stably maintained during hostile conditions of ethanol fermentations in dextrose or molasses, and even during biomass recycling.
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29
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Transcriptional and metabolic response in yeast Saccharomyces cerevisiae
cells during polyethylene glycol-dependent transformation. J Basic Microbiol 2008; 49:73-81. [DOI: 10.1002/jobm.200800123] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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31
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Comparison between polyethylene glycol- and polyethylenimine-mediated transformation of Aspergillus nidulans. Curr Genet 2008; 54:95-103. [PMID: 18649081 DOI: 10.1007/s00294-008-0204-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 07/02/2008] [Accepted: 07/04/2008] [Indexed: 10/21/2022]
Abstract
Genetic transformation of many filamentous fungi is carried out by a protocol that utilizes polyethylene glycol (PEG) and calcium ion (Ca2+). This method has remained practically unchanged for more than 20 years, but the roles these molecules play are not definitively understood. To gain a better understanding, we have compared PEG transformation to a protocol using polyethylenimine (PEI) that is the basis for non-viral transfection in mammals and which has a well established molecular model for assisting DNA uptake. Protoplasts of Aspergillus nidulans could be transformed in the presence of Ca2+ with a relatively high ratio of PEI to DNA molecules. By comparing PEI and PEG in terms of interaction with DNA, fungal protoplasts, and response to different transformation conditions, we propose that the role of PEG is most likely to function after transforming DNA is incorporated into protoplasts, rather than the accepted view that it functions outside of the cell. Confirmation that protoplast fusion was not involved in DNA uptake is consistent with this hypothesis.
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Electrofused giant protoplasts of Saccharomyces cerevisiae as a novel system for electrophysiological studies on membrane proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:1493-500. [DOI: 10.1016/j.bbamem.2008.03.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Revised: 03/15/2008] [Accepted: 03/20/2008] [Indexed: 11/26/2022]
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Mot3, a Zn finger transcription factor that modulates gene expression and attenuates mating pheromone signaling in Saccharomyces cerevisiae. Genetics 1998; 149:879-92. [PMID: 9611199 PMCID: PMC1460180 DOI: 10.1093/genetics/149.2.879] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In the yeast Saccharomyces cerevisiae, mating pheromone response is initiated by activation of a G protein- and mitogen-activated protein (MAP) kinase-dependent signaling pathway and attenuated by several mechanisms that promote adaptation or desensitization. To identify genes whose products negatively regulate pheromone signaling, we screened for mutations that suppress the hyperadaptive phenotype of wild-type cells overexpressing signaling-defective G protein beta subunits. This identified recessive mutations in MOT3, which encodes a nuclear protein with two Cys2-His2 Zn fingers. MOT3 was found to be a dosage-dependent inhibitor of pheromone response and pheromone-induced gene expression and to require an intact signaling pathway to exert its effects. Several results suggested that Mot3 attenuates expression of pheromone-responsive genes by mechanisms distinct from those used by the negative transcriptional regulators Cdc36, Cdc39, and Mot2. First, a Mot3-lexA fusion functions as a transcriptional activator. Second, Mot3 is a dose-dependent activator of several genes unrelated to pheromone response, including CYC1, SUC2, and LEU2. Third, insertion of consensus Mot3 binding sites (C/A/T)AGG(T/C)A activates a promoter in a MOT3-dependent manner. These findings, and the fact that consensus binding sites are found in the 5' flanking regions of many yeast genes, suggest that Mot3 is a globally acting transcriptional regulator. We hypothesize that Mot3 regulates expression of factors that attenuate signaling by the pheromone response pathway.
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Abstract
A new gene (SUT1) of Saccharomyces cerevisiae, implicated in sterol uptake, was isolated from a yeast genomic library constructed in a high-copy-number vector by virtue of conferring resistance to fenpropimorph in medium supplemented with ergosterol. The high expression of SUT1 in sterol auxotrophic mutant strains alleviates the requirement for accessory mutations affecting heme biosynthesis and allows sterol uptake in aerobiosis. Measurements of [14C]cholesterol uptake confirmed that SUT1 is involved in sterol absorption. Within the 4.1-kb insert isolated, the functional gene was localised on a 1.7-kb DNA fragment. The nucleotide sequence encodes a predicted protein of 299 amino acids. Northern blot analysis revealed that SUT1 is a new member of the hypoxic gene family. Gene disruption showed that SUT1 is not essential for aerobic or anaerobic yeast growth.
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Fus2 localizes near the site of cell fusion and is required for both cell fusion and nuclear alignment during zygote formation. J Biophys Biochem Cytol 1995; 130:1283-96. [PMID: 7559752 PMCID: PMC2120577 DOI: 10.1083/jcb.130.6.1283] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Zygote formation occurs through tightly coordinated cell and nuclear fusion events. Genetic evidence suggests that the FUS2 gene product promotes cell fusion during zygote formation in Saccharomyces cerevisiae, functioning with the Fus1 plasma membrane protein at or before cell wall and plasma membrane fusion. Here we report the sequence of the FUS2 gene, localization of Fus2 protein, and show that fus1 and fus2 mutants have distinct defects in cell fusion. FUS2 encodes a unique open reading frame of 617 residues that only is expressed in haploid cells in response to mating pheromone. Consistent with a role in cell fusion, Fus2 protein localizes with discrete structures that could be of cytoskeletal or vesicular origin that accumulate at the tip of pheromone-induced shmoos and at the junction of paired cells in zygotes. Fus2 is predicted to be a coiled-coil protein and fractionates with a 100,000 g pellet, suggesting that it is associated with cytoskeleton, membranes, or other macromolecular structures. Fus2 may interact with structures involved in the alignment of the nuclei during cell fusion, because fus2 mutants have strong defects in karyogamy and fail to orient microtubules between parental nuclei in zygotes. In contrast, fus1 mutants show no karyogamy defects. These, and other results suggest that Fus2 defines a novel cell fusion function and subcellular structure that is also required for the alignment of parental nuclei before nuclear fusion.
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Industrial yeast strain improvement: construction of a highly flocculent yeast with a killer character by protoplast fusion. JOURNAL OF INDUSTRIAL MICROBIOLOGY 1995; 15:94-102. [PMID: 7576466 DOI: 10.1007/bf01569806] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Conditions were optimized for rapid release and improved regeneration of protoplasts of Saccharomyces cerevisiae NCIM 3458. Rapid protoplast release was also obtained with representatives of several other yeast genera under the modified conditions of treatment. The application of the procedure in construction of a highly flocculent Saccharomyces cerevisiae with a killer character is described. Fusion was effected between UV-killed protoplasts of S. cerevisiae NCIM 3578 with a killer character and live protoplasts of the highly flocculent S. cerevisiae NCIM 3528 in the presence of polyethylene glycol (PEG) 6000. Fusants were selected using benomyl resistance as marker, the killer toxin producer rather than the highly flocculent yeast being resistant to the fungicide at a concentration of 100 micrograms ml-1. Fusants were also characterized by their DNA contents, capacity for ethanolic fermentation of molasses sugar and levels of invertase, alcohol dehydrogenase and pyruvate decarboxylase activities.
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Abstract
An improved lithium acetate (LiAc)/single-stranded DNA (SS-DNA)/polyethylene glycol (PEG) protocol which yields > 1 x 10(6) transformants/micrograms plasmid DNA and the original protocol described by Schiestl and Gietz (1989) were used to investigate aspects of the mechanism of LiAc/SS-DNA/PEG transformation. The highest transformation efficiency was observed when 1 x 10(8) cells were transformed with 100 ng plasmid DNA in the presence of 50 micrograms SS carrier DNA. The yield of transformants increased linearly up to 5 micrograms plasmid per transformation. A 20-min heat shock at 42 degrees C was necessary for maximal yields. PEG was found to deposit both carrier DNA and plasmid DNA onto cells. SS carrier DNA bound more effectively to the cells and caused tighter binding of 32P-labelled plasmid DNA than did double-stranded (DS) carrier. The LiAc/SS-DNA/PEG transformation method did not result in cell fusion. DS carrier DNA competed with DS vector DNA in the transformation reaction. SS plasmid DNA transformed cells poorly in combination with both SS and DS carrier DNA. The LiAc/SS-DNA/PEG method was shown to be more effective than other treatments known to make cells transformable. A model for the mechanism of transformation by the LiAc/SS-DNA/PEG method is discussed.
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The use of flow cytometry and small-scale brewing in protoplast fusion: Exclusion of undesired phenotypes in yeasts. Enzyme Microb Technol 1994. [DOI: 10.1016/0141-0229(94)90057-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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41
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Electrofusion of brewers' yeast protoplasts and enrichment of the fusants using a flow cytometer. Enzyme Microb Technol 1993. [DOI: 10.1016/0141-0229(93)90172-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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42
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Sister chromatids are preferred over homologs as substrates for recombinational repair in Saccharomyces cerevisiae. Genetics 1992; 132:387-402. [PMID: 1427035 PMCID: PMC1205144 DOI: 10.1093/genetics/132.2.387] [Citation(s) in RCA: 384] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
A diploid Saccharomyces cerevisiae strain was constructed in which the products of both homolog recombination and unequal sister chromatid recombination events could be selected. This strain was synchronized in G1 or in G2, irradiated with X-rays to induce DNA damage, and monitored for levels of recombination. Cells irradiated in G1 were found to repair recombinogenic damage primarily by homolog recombination, whereas those irradiated in G2 repaired such damage preferentially by sister chromatid recombination. We found, as have others, that G1 diploids were much more sensitive to the lethal effects of X-ray damage than were G2 diploids, especially at higher doses of irradiation. The following possible explanations for this observation were tested: G2 cells have more potential templates for repair than G1 cells; G2 cells are protected by the RAD9-mediated delay in G2 following DNA damage; sister chromatids may share more homology than homologous chromosomes. All these possibilities were ruled out by appropriate tests. We propose that, due to a special relationship they share, sister chromatids are not only preferred over homologous chromatids as substrates for recombinational repair, but have the capacity to repair more DNA damage than do homologs.
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Abstract
The budding yeast Saccharomyces cerevisiae is now widely used as a model organism in the study of gene structure, function, and regulation in addition to its more traditional use as a workhorse of the brewing and baking industries. In this article the plethora of methods available for manipulating the genome of S. cerevisiae are reviewed. This will include a discussion of methods for manipulating individual genes and whole chromosomes, and will address both classic genetic and recombinant DNA-based methods. Furthermore, a critical evaluation of the various genetic strategies for genetically manipulating this simple eukaryote will be included, highlighting the requirements of both the new and the more traditional biotechnology industries.
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swi6, a gene required for mating-type switching, prohibits meiotic recombination in the mat2-mat3 "cold spot" of fission yeast. Genetics 1991; 129:1033-42. [PMID: 1783290 PMCID: PMC1204768 DOI: 10.1093/genetics/129.4.1033] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Mitotic interconversion of the mating-type locus (mat1) of the fission yeast Schizosaccharomyces pombe is initiated by a double-strand break at mat1. The mat2 and mat3 loci act as nonrandom donors of genetic information for mat1 switching such that switches occur primarily (or only) to the opposite mat1 allele. Location of the mat1 "hot spot" for transposition should be contrasted with the "cold spot" of meiotic recombination located within the adjoining mat2-mat3 interval. That is, meiotic interchromosomal recombination in mat2, mat3 and the intervening 15-kilobase region does not occur at all. swi2 and swi6 switching-deficient mutants possess the normal level of double-strand break at mat1, yet they fail to switch efficiently. By testing for meiotic recombination in the cold spot, we found the usual lack of recombination in a swi2 mutant but a significant level of recombination in a swi6 mutant. Therefore, the swi6 gene function is required to keep the donor loci inert for interchromosomal recombination. This finding, combined with the additional result that switching primarily occurs intrachromosomally, suggests that the donor loci are made accessible for switching by folding them onto mat1, thus causing the cold spot of recombination.
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Electrofusion of an industrial Baker’s yeast strain with a sour dough yeast. Appl Biochem Biotechnol 1991. [DOI: 10.1007/bf02921516] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Flow cytometric detection of yeast by in situ hybridization with a fluorescent ribosomal RNA probe. J Microbiol Methods 1990. [DOI: 10.1016/0167-7012(90)90002-n] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Isolation and nucleotide sequence of an autonomously replicating sequence (ARS) element functional in Candida albicans and Saccharomyces cerevisiae. MOLECULAR & GENERAL GENETICS : MGG 1990; 221:210-8. [PMID: 2196431 DOI: 10.1007/bf00261723] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
An 8.6-kb fragment was isolated from an EcoRI digest of Candida albicans ATCC 10261 genomic DNA which conferred the property of autonomous replication in Saccharomyces cervisiae on the otherwise non-replicative plasmid pMK155 (5.6 kb). The DNA responsible for the replicative function was subcloned as a 1.2-kb fragment onto a non-replicative plasmid (pRC3915) containing the C. albicans URA3 and LEU2 genes to form plasmid pRC3920. This plasmid was capable of autonomous replication in both S. cerevisiae and C. albicans and transformed S. cerevisiae AH22 (leu2-) to Leu+ at a frequency of 2.15 x 10(3) transformants per microgram DNA, and transformed C. albicans SGY-243 (delta ura3) to Ura+ at a frequency of 1.91 x 10(3) transformants per microgram DNA. Sequence analysis of the cloned DNA revealed the presence of two identical regions of eleven base pairs (5'TTTTATGTTTT3') which agreed with the consensus of autonomously replicating sequence (ARS) cores functional in S. cerevisiae. In addition there were two 10/11 and numerous 9/11 matches to the core consensus. The two 11/11 matches to the consensus, CaARS1 and CaARS2, were located on opposite strands in a non-coding AT-rich region and were separated by 107 bp. Also present on the C. albicans DNA, 538 bp from the ARS cores, was a gene for 5S rRNA which showed sequence homology with several other yeast 5S rRNA genes.(ABSTRACT TRUNCATED AT 250 WORDS)
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