scholarly journals Selective system based on fragments of the M1 virus for the yeast Saccharomyces cerevisiae transformation

2020 ◽  
Author(s):  
Dmitri Mikhailovich Muzaev ◽  
Andrey Mikhailovitch Rumyantsev ◽  
Ousama Raek Al Shanaa ◽  
Elena Viktorovna Sambuk

Background. A selective system based on the M1 virus of the yeast Saccharomyces cerevisiae was proposed. Methods. To create a recipient strain, a DNA fragment encoding the killer toxin of the M1 virus under the control of the regulated promoter of the GAL1 gene was inserted into the genome of S. cerevisiae strains Y-1236 and Y-2177. Results. Integration of such expression cassette leads to the conditional lethality - resulting strains die on a medium with galactose when killer toxin synthesis occurs. A linear DNA fragment containing the gene of interest flanked by sequences homologous to the promoter of the GAL1 gene and the termination region of the CYC1 gene is used to transform the obtained strains. During transformation due to homologous recombination, the sequence encoding the killer toxin is cleaved and the transformants grow on a medium with galactose. Conclusion. The proposed selective system combines the main advantages of other systems: the use of simple media, without the need to add expensive antibiotics, and a simplified technique for constructing expression cassettes and selecting transformants.

2005 ◽  
Vol 33 (6) ◽  
pp. 1447-1450 ◽  
Author(s):  
M.A. Macris ◽  
P. Sung

Homologous recombination (HR) is a major pathway for the elimination of DNA DSBs (double-strand breaks) induced by high-energy radiation and chemicals, or that arise due to endogenous damage and stalled DNA replication forks. If not processed properly, DSBs can lead to cell death, chromosome aberrations and tumorigenesis. Even though HR is important for genome maintenance, it can also interfere with other DNA repair mechanisms and cause gross chromosome rearrangements. In addition, HR can generate DNA or nucleoprotein intermediates that elicit prolonged cell-cycle arrest and sometimes cell death. Genetic analyses in the yeast Saccharomyces cerevisiae have revealed a central role of the Srs2 helicase in preventing untimely HR events and in inhibiting the formation of potentially deleterious DNA structures or nucleoprotein complexes upon DNA replication stress. Paradoxically, efficient repair of DNA DSBs by HR is dependent on Srs2. In this paper, we review recent molecular studies aimed at deciphering the multifaceted role of Srs2 in HR and other cellular processes. These studies have provided critical insights into how HR is regulated in order to preserve genomic integrity and promote cell survival.


2012 ◽  
Vol 48 (3) ◽  
pp. 284-290 ◽  
Author(s):  
A. Yu. Chernenkov ◽  
D. V. Fedorov ◽  
L. M. Gracheva ◽  
T. A. Evstuhina ◽  
S. V. Kovaltsova ◽  
...  

1993 ◽  
Vol 13 (5) ◽  
pp. 2697-2705
Author(s):  
R H Schiestl ◽  
M Dominska ◽  
T D Petes

When the yeast Saccharomyces cerevisiae was transformed with DNA that shares no homology to the genome, three classes of transformants were obtained. In the most common class, the DNA was inserted as the result of a reaction that appears to require base pairing between the target sequence and the terminal few base pairs of the transforming DNA fragment. In the second class, no such homology was detected, and the transforming DNA was integrated next to a CTT or GTT in the target; it is likely that these integration events were mediated by topoisomerase I. The final class involved the in vivo ligation of transforming DNA with nucleus-localized linear fragments of mitochondrial DNA.


1991 ◽  
Vol 113 (3) ◽  
pp. 527-538 ◽  
Author(s):  
K Redding ◽  
C Holcomb ◽  
R S Fuller

The Kex2 protein of the yeast Saccharomyces cerevisiae is a membrane-bound, Ca2(+)-dependent serine protease that cleaves the precursors of the mating pheromone alpha-factor and the M1 killer toxin at pairs of basic residues during their transport through the secretory pathway. To begin to characterize the intracellular locus of Kex2-dependent proteolytic processing, we have examined the subcellular distribution of Kex2 protein in yeast by indirect immunofluorescence. Kex2 protein is located at multiple, discrete sites within wild-type yeast cells (average, 3.0 +/- 1.7/mother cell). Qualitatively similar fluorescence patterns are observed at elevated levels of expression, but no signal is found in cells lacking the KEX2 gene. Structures containing Kex2 protein are not concentrated at a perinuclear location, but are distributed throughout the cytoplasm at all phases of the cell cycle. Kex2-containing structures appear in the bud at an early, premitotic stage. Analysis of conditional secretory (sec) mutants demonstrates that Kex2 protein ordinarily progresses from the ER to the Golgi but is not incorporated into secretory vesicles, consistent with the proposed localization of Kex2 protein to the yeast Golgi complex.


Genetics ◽  
1992 ◽  
Vol 131 (4) ◽  
pp. 833-850
Author(s):  
P R Sutton ◽  
S W Liebman

Abstract The structures of two unusual deletions from the yeast Saccharomyces cerevisiae are described. These deletions extend from a single Ty1 retrotransposon to an endpoint near a repetitive tRNA(Gly) gene. The deletions suggest that unique sequences flanked by two nonidentical repetitive sequences, or bordered on only one side by a transposable element, have the potential to be mobilized in the yeast genome. Models for the formation of these two unusual deletions were tested by isolating and analyzing 32 additional unusual deletions of the CYC1 region that extend from a single Ty1 retrotransposon. Unlike the most common class of deletions recovered in this region, these deletions are not attributable solely to homologous recombination among repetitive Ty1 or delta elements. They arose by two distinct mechanisms. In an SPT8 genetic background, most unusual deletions arose by transposition of a Ty1 element to a position adjacent to a tRNA(Gly) gene followed by Ty1-Ty1 recombination. In an spt8 strain, where full-length Ty1 transcription and, therefore, transposition are reduced, most deletions were due to gene conversion of a 7-kb chromosomal interval flanked by a Ty1 element and a tRNA(Gly) gene.


1993 ◽  
Vol 13 (5) ◽  
pp. 2697-2705 ◽  
Author(s):  
R H Schiestl ◽  
M Dominska ◽  
T D Petes

When the yeast Saccharomyces cerevisiae was transformed with DNA that shares no homology to the genome, three classes of transformants were obtained. In the most common class, the DNA was inserted as the result of a reaction that appears to require base pairing between the target sequence and the terminal few base pairs of the transforming DNA fragment. In the second class, no such homology was detected, and the transforming DNA was integrated next to a CTT or GTT in the target; it is likely that these integration events were mediated by topoisomerase I. The final class involved the in vivo ligation of transforming DNA with nucleus-localized linear fragments of mitochondrial DNA.


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