scholarly journals Multiple, Tandem Plasmid Integration inSaccharomyces cerevisiae

1983 ◽  
Vol 3 (4) ◽  
pp. 747-749 ◽  
Author(s):  
Terry L. Orr-Weaver ◽  
Jack W. Szostak

Nonreplicating plasmids transformSaccharomyces cerevisiaeby recombining with a homologous site in the genome. Frequently, multiple copies of the plasmid integrate in a tandem array. We show that, after transformation with restriction enzyme-cut plasmids, most, if not all, multimers arise by sequential integration of plasmid molecules into the same genomic location.

1983 ◽  
Vol 3 (4) ◽  
pp. 747-749
Author(s):  
Terry L. Orr-Weaver ◽  
Jack W. Szostak

Nonreplicating plasmids transform Saccharomyces cerevisiae by recombining with a homologous site in the genome. Frequently, multiple copies of the plasmid integrate in a tandem array. We show that, after transformation with restriction enzyme-cut plasmids, most, if not all, multimers arise by sequential integration of plasmid molecules into the same genomic location.


1991 ◽  
Vol 11 (5) ◽  
pp. 2905-2908 ◽  
Author(s):  
W R Widner ◽  
Y Matsumoto ◽  
R B Wickner

The 20S RNA of Saccharomyces cerevisiae is a single-stranded, circular RNA virus. A previous study suggested that this RNA is part of a 32S ribonucleoprotein particle, being associated with multiple copies of a 23-kilodalton protein. We show here that this protein is, in fact, the chromosome-encoded heat shock protein Hsp26. Furthermore, it is apparently not associated with 20S RNA and plays no obvious role in the life cycle of the virus.


1996 ◽  
Vol 16 (8) ◽  
pp. 4387-4395 ◽  
Author(s):  
D Mack ◽  
K Nishimura ◽  
B K Dennehey ◽  
T Arbogast ◽  
J Parkinson ◽  
...  

The Rho-type GTPase Cdc42p is required for cell polarization and bud emergence in Saccharomyces cerevisiae. To identify genes whose functions are linked to CDC42, we screened for (i) multicopy suppressors of a Ts- cdc42 mutant, (ii) mutants that require multiple copies of CDC42 for survival, and (iii) mutations that display synthetic lethality with a partial-loss-of-function allele of CDC24, which encodes a guanine nucleotide exchange factor for Cdc42p. In all three screens, we identified a new gene, BEM4. Cells from which BEM4 was deleted were inviable at 37 degrees C. These cells became unbudded, large, and round, consistent with a model in which Bem4p acts together with Cdc42p in polarity establishment and bud emergence. In some strains, the ability of CDC42 to serve as a multicopy suppressor of the Ts- growth defect of deltabem4 cells required co-overexpression of Rho1p, which is an essential Rho-type GTPase necessary for cell wall integrity. This finding suggests that Bem4p also affects Rho1p function. Bem4p displayed two-hybrid interactions with Cdc42p, Rho1p, and two of the three other known yeast Rho-type GTPases, suggesting that Bem4p can interact with multiple Rho-type GTPases. Models for the role of Bem4p include that it serves as a chaperone or modulates the interaction of these GTPases with one or more of their targets or regulators.


Fermentation ◽  
2018 ◽  
Vol 4 (3) ◽  
pp. 59 ◽  
Author(s):  
Tingting Liu ◽  
Shuangcheng Huang ◽  
Anli Geng

Cost-effective production of cellulosic ethanol requires robust microorganisms for rapid co-fermentation of glucose and xylose. This study aims to develop a recombinant diploid xylose-fermenting Saccharomyces cerevisiae strain for efficient conversion of lignocellulosic biomass sugars to ethanol. Episomal plasmids harboring codon-optimized Piromyces sp. E2 xylose isomerase (PirXylA) and Orpinomyces sp. ukk1 xylose (OrpXylA) genes were constructed and transformed into S. cerevisiae. The strain harboring plasmids with tandem PirXylA was favorable for xylose utilization when xylose was used as the sole carbon source, while the strain harboring plasmids with tandem OrpXylA was beneficial for glucose and xylose cofermentation. PirXylA and OrpXylA genes were also individually integrated into the genome of yeast strains in multiple copies. Such integration was beneficial for xylose alcoholic fermentation. The respiration-deficient strain carrying episomal or integrated OrpXylA genes exhibited the best performance for glucose and xylose co-fermentation. This was partly attributed to the high expression levels and activities of xylose isomerase. Mating a respiration-efficient strain carrying the integrated PirXylA gene with a respiration-deficient strain harboring integrated OrpXylA generated a diploid recombinant xylose-fermenting yeast strain STXQ with enhanced cell growth and xylose fermentation. Co-fermentation of 162 g L−1 glucose and 95 g L−1 xylose generated 120.6 g L−1 ethanol in 23 h, with sugar conversion higher than 99%, ethanol yield of 0.47 g g−1, and ethanol productivity of 5.26 g L−1·h−1.


1988 ◽  
Vol 8 (11) ◽  
pp. 4675-4684 ◽  
Author(s):  
F R Cross

The mating pheromone alpha-factor arrests Saccharomyces cerevisiae MATa cells in the G1 phase of the cell cycle. Size control is also exerted in G1, since cells do not exit G1 until they have attained a critical size. A dominant mutation (DAF1-1) which causes both alpha-factor resistance and small cell size (volume about 0.6-fold that of the wild type) has been isolated and characterized genetically and by molecular cloning. Several alpha-factor-induced mRNAs were induced equivalently in daf1+ and DAF1-1 cells. The DAF1-1 mutation consisted of a termination codon two-thirds of the way through the daf1+ coding sequence. A chromosomal deletion of DAF1 produced by gene transplacement increased cell volume about 1.5-fold; thus, DAF1-1 may be a hyperactive or deregulated allele of a nonessential gene involved in G1 size control. Multiple copies of DAF1-1 also greatly reduced the duration of the G1 phase of the cell cycle.


1987 ◽  
Vol 7 (2) ◽  
pp. 813-820
Author(s):  
M J Holland ◽  
T Yokoi ◽  
J P Holland ◽  
K Myambo ◽  
M A Innis

The intracellular concentrations of the polypeptides encoded by the two enolase (ENO1 and ENO2) and three glyceraldehyde-3-phosphate dehydrogenase (TDH1, TDH2, and TDH3) genes were coordinately reduced more than 20-fold in a Saccharomyces cerevisiae strain carrying the gcr1-1 mutation. The steady-state concentration of glyceraldehyde-3-phosphate dehydrogenase mRNA was shown to be approximately 50-fold reduced in the mutant strain. Overexpression of enolase and glyceraldehyde-3-phosphate dehydrogenase in strains carrying multiple copies of either ENO1 or TDH3 was reduced more than 50-fold in strains carrying the gcr1-1 mutation. These results demonstrated that the GCR1 gene encodes a trans-acting factor which is required for efficient and coordinate expression of these glycolytic gene families. The GCR1 gene and the gcr1-1 mutant allele were cloned and sequenced. GCR1 encodes a predicted 844-amino-acid polypeptide; the gcr1-1 allele contains a 1-base-pair insertion mutation at codon 304. A null mutant carrying a deletion of 90% of the GCR1 coding sequence and a URA3 gene insertion was constructed by gene replacement. The phenotype of a strain carrying this null mutation was identical to that of the gcr1-1 mutant strain.


1995 ◽  
Vol 15 (1) ◽  
pp. 264-271 ◽  
Author(s):  
M Wu ◽  
B Repetto ◽  
D M Glerum ◽  
A Tzagoloff

The FAD1 gene of Saccharomyces cerevisiae has been selected from a genomic library on the basis of its ability to partially correct the respiratory defect of pet mutants previously assigned to complementation group G178. Mutants in this group display a reduced level of flavin adenine dinucleotide (FAD) and an increased level of flavin mononucleotide (FMN) in mitochondria. The restoration of respiratory capability by FAD1 is shown to be due to extragenic suppression. FAD1 codes for an essential yeast protein, since disruption of the gene induces a lethal phenotype. The FAD1 product has been inferred to be yeast FAD synthetase, an enzyme that adenylates FMN to FAD. This conclusion is based on the following evidence. S. cerevisiae transformed with FAD1 on a multicopy plasmid displays an increase in FAD synthetase activity. This is also true when the gene is expressed in Escherichia coli. Lastly, the FAD1 product exhibits low but significant primary sequence similarity to sulfate adenyltransferase, which catalyzes a transfer reaction analogous to that of FAD synthetase. The lower mitochondrial concentration of FAD in G178 mutants is proposed to be caused by an inefficient exchange of external FAD for internal FMN. This is supported by the absence of FAD synthetase activity in yeast mitochondria and the presence of both extramitochondrial and mitochondrial riboflavin kinase, the preceding enzyme in the biosynthetic pathway. A lesion in mitochondrial import of FAD would account for the higher concentration of mitochondrial FMN in the mutant if the transport is catalyzed by an exchange carrier. The ability of FAD1 to suppress impaired transport of FAD is explained by mislocalization of the synthetase in cells harboring multiple copies of the gene. This mechanism of suppression is supported by the presence of mitochondrial FAD synthetase activity in S. cerevisiae transformed with FAD1 on a high-copy-number plasmid but not in mitochondrial of a wild-type strain.


1998 ◽  
Vol 18 (3) ◽  
pp. 1736-1745 ◽  
Author(s):  
Palaniyandi Manivasakam ◽  
Robert H. Schiestl

ABSTRACT The BamHI restriction enzyme mediates integration of nonhomologous DNA into the Saccharomyces cerevisiae genome (R. H. Schiestl and T. D. Petes, Proc. Natl. Acad. Sci. USA 88:7585–7589, 1991). The present study investigates the mechanism of such events: in particular, the mediating activity of various restriction enzymes and the processing of resultant fragment ends. Our results show that in addition to BamHI, BglII and KpnI increase DNA integration efficiencies severalfold, while Asp718, HindIII, EcoRI,SalI, SmaI, HpaI, MscI, and SnaBI do not. Secondly, the three active enzymes stimulated integrations only of fragments containing 5′ or 3′ overhangs but not of blunt-ended fragments. Thirdly, integrations mediated by one enzyme and utilizing a substrate created by another required at least 2 bp of homology. Furthermore, an Asp718 fragment possessing a 5′ overhang integrated into a KpnI (isoschizomer) site possessing a 3′ overhang, most likely by filling of the 5′ overhang followed by 5′ exonuclease digestion to produce a 3′ end. We classified and analyzed the restriction enzyme-mediated integration events in the context of their genomic positions. The majority of events integrated into single sites. In the remaining 6 of 19 cases each end of the plasmid inserted into a different sequence, producing rearrangements such as duplications, deletions, and translocations.


1987 ◽  
Vol 7 (10) ◽  
pp. 3637-3645 ◽  
Author(s):  
J Schultz ◽  
M Carlson

Mutations in the SSN6 gene suppress the invertase derepression defect caused by a lesion in the SNF1 protein kinase gene. We cloned the SSN6 gene of Saccharomyces cerevisiae and identified its 3.3-kilobase poly(A)-containing RNA. Disruption of the gene caused phenotypes similar to, but more severe than, those caused by missense mutations: high-level constitutivity for invertase, clumpiness, temperature-sensitive growth, alpha-specific mating defects, and failure to homozygous diploids to sporulate. In contrast, the presence of multiple copies of SSN6 interfered with derepression of invertase. An ssn6 mutation was also shown to cause glucose-insensitive expression of a GAL10-lacZ fusion and maltase. The mating defects of MAT alpha ssn6 strains were associated with production of two a-specific products, a-factor and barrier, and reduced levels of alpha-factor; no deficiency of MAT alpha 2 RNA was detected. We showed that ssn6 partially restored invertase expression in a cyr1-2 mutant, although ssn6 was clearly not epistatic to cyr1-2. We also determined the nucleotide sequence of SSN6, which is predicted to encode a 107-kilodalton protein with stretches of polyglutamine and poly(glutamine-alanine). Possible functions of the SSN6 product are discussed.


1989 ◽  
Vol 9 (4) ◽  
pp. 1659-1666 ◽  
Author(s):  
P K Hwang ◽  
S Tugendreich ◽  
R J Fletterick

In yeast cells, the activity of glycogen phosphorylase is regulated by cyclic AMP-mediated phosphorylation of the enzyme. We have previously cloned the gene for glycogen phosphorylase (GPH1) in Saccharomyces cerevisiae. To assess the role of glycogen and phosphorylase-catalyzed glycogenolysis in the yeast life cycle, yeast strains lacking a functional GPH1 gene or containing multiple copies of the gene were constructed. GPH1 was found not to be an essential gene in yeast cells. Haploid cells disrupted in GPH1 lacked phosphorylase activity and attained higher levels of intracellular glycogen but otherwise were similar to wild-type cells. Diploid cells homozygous for the disruption were able to sporulate and give rise to viable ascospores. Absence of functional GPH1 did not impair cells from synthesizing and storing trehalose. Increases in phosphorylase activity of 10- to 40-fold were detected in cells carrying multiple copies of GPH1-containing 2 microns plasmid. Northern (RNA) analysis indicated that GPH1 transcription was induced at the late exponential growth phase, almost simultaneous with the onset of intracellular glycogen accumulation. Thus, the low level of glycogen in exponential cells was not primarily maintained through regulating the phosphorylation state of a constitutive amount of phosphorylase. GPH1 did not appear to be under formal glucose repression, since transcriptional induction occurred well in advance of glucose depletion from the medium.


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