scholarly journals Heritable capture of heterochromatin dynamics in Saccharomyces cerevisiae

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Anne E Dodson ◽  
Jasper Rine
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Single Molecule ◽  
Genome Stability ◽  
Gene Repression ◽  
Cell Divisions ◽  
Rna Fish ◽  
Eukaryotic Gene ◽  
The Stability ◽  
Lines Of Evidence

Heterochromatin exerts a heritable form of eukaryotic gene repression and contributes to chromosome segregation fidelity and genome stability. However, to date there has been no quantitative evaluation of the stability of heterochromatic gene repression. We designed a genetic strategy to capture transient losses of gene silencing in Saccharomyces as permanent, heritable changes in genotype and phenotype. This approach revealed rare transcription within heterochromatin that occurred in approximately 1/1000 cell divisions. In concordance with multiple lines of evidence suggesting these events were rare and transient, single-molecule RNA FISH showed that transcription was limited. The ability to monitor fluctuations in heterochromatic repression uncovered previously unappreciated roles for Sir1, a silencing establishment factor, in the maintenance and/or inheritance of silencing. In addition, we identified the sirtuin Hst3 and its histone target as contributors to the stability of the silenced state. These approaches revealed dynamics of a heterochromatin function that have been heretofore inaccessible.

scholarly journals Shugoshin Promotes Sister Kinetochore Biorientation in Saccharomyces cerevisiae

2008 ◽  
Vol 19 (3) ◽  
pp. 1199-1209 ◽  
Author(s):  
Brendan M. Kiburz ◽  
Angelika Amon ◽  
Adele L. Marston
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Minor Role ◽  
Meiotic Cell ◽  
Homologous Chromosomes ◽  
Cell Divisions ◽  
Sister Chromatids ◽  
Sister Kinetochore ◽  
A Minor ◽  
Meiosis I

Chromosome segregation must be executed accurately during both mitotic and meiotic cell divisions. Sgo1 plays a key role in ensuring faithful chromosome segregation in at least two ways. During meiosis this protein regulates the removal of cohesins, the proteins that hold sister chromatids together, from chromosomes. During mitosis, Sgo1 is required for sensing the absence of tension caused by sister kinetochores not being attached to microtubules emanating from opposite poles. Here we describe a differential requirement for Sgo1 in the segregation of homologous chromosomes and sister chromatids. Sgo1 plays only a minor role in segregating homologous chromosomes at meiosis I. In contrast, Sgo1 is important to bias sister kinetochores toward biorientation. We suggest that Sgo1 acts at sister kinetochores to promote their biorientation.

scholarly journals Structure/Function Analysis of the Hif1 Histone Chaperone in Saccharomyces cerevisiae

2021 ◽  
Author(s):  
Nora Saud Dannah
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Genome Stability ◽  
Function Analysis ◽  
Molecular Genetic ◽  
Histone Chaperone ◽  
Chromatin Assembly ◽  
Biological Processes ◽  
Genetic Approach ◽  
Yeast Saccharomyces Cerevisiae

Understanding the regulation of chromatin structure is a vital aspect of molecular biology regarding its influences on biological processes such as DNA replication, transcription (gene expression), DNA repair, chromosome segregation and recombination. In the budding yeast Saccharomyces cerevisiae, a histone chaperone called Hif1 has been found in the nuclei as having a functional role in chromatin assembly. Hif1 is a homolog of the human protein NASP that is involved in the maintenance of genome stability. Previously, Hif1 has been shown to physically interact with Hat1, Hat2 and H3/H4 to form the NuB4 complex directly involved in chromatin assembly. A molecular genetic approach was conducted to determine which domain of Hif1 is involved in the interaction with the HAT1 complex.

scholarly journals The Epigenetic Pathways to Ribosomal DNA Silencing

2016 ◽  
Vol 80 (3) ◽  
pp. 545-563 ◽  
Author(s):  
Rakesh Srivastava ◽  
Rashmi Srivastava ◽  
Seong Hoon Ahn
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Ribosomal Dna ◽  
Genome Stability ◽  
Cellular Aging ◽  
Content Type ◽  
Eukaryotic Chromatin ◽  
Normal Life Span ◽  
Protein Components ◽  
Dna Silencing

SUMMARYHeterochromatin is the transcriptionally repressed portion of eukaryotic chromatin that maintains a condensed appearance throughout the cell cycle. At sites of ribosomal DNA (rDNA) heterochromatin, epigenetic states contribute to gene silencing and genome stability, which are required for proper chromosome segregation and a normal life span. Here, we focus on recent advances in the epigenetic regulation of rDNA silencing inSaccharomyces cerevisiaeand in mammals, including regulation by several histone modifications and several protein components associated with the inner nuclear membrane within the nucleolus. Finally, we discuss the perturbations of rDNA epigenetic pathways in regulating cellular aging and in causing various types of diseases.

scholarly journals Structure/Function Analysis of the Hif1 Histone Chaperone in Saccharomyces cerevisiae

2021 ◽  
Author(s):  
Nora Saud Dannah
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Genome Stability ◽  
Function Analysis ◽  
Molecular Genetic ◽  
Histone Chaperone ◽  
Chromatin Assembly ◽  
Biological Processes ◽  
Genetic Approach ◽  
Yeast Saccharomyces Cerevisiae

Understanding the regulation of chromatin structure is a vital aspect of molecular biology regarding its influences on biological processes such as DNA replication, transcription (gene expression), DNA repair, chromosome segregation and recombination. In the budding yeast Saccharomyces cerevisiae, a histone chaperone called Hif1 has been found in the nuclei as having a functional role in chromatin assembly. Hif1 is a homolog of the human protein NASP that is involved in the maintenance of genome stability. Previously, Hif1 has been shown to physically interact with Hat1, Hat2 and H3/H4 to form the NuB4 complex directly involved in chromatin assembly. A molecular genetic approach was conducted to determine which domain of Hif1 is involved in the interaction with the HAT1 complex.

scholarly journals Genetic architecture of a mutation’s expressivity and penetrance

2020 ◽  
Author(s):  
Rachel Schell ◽  
Martin N. Mullis ◽  
Takeshi Matsui ◽  
Ryan Foree ◽  
Ian M. Ehrenreich
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Genome Stability ◽  
Genetic Architecture ◽  
Genetic Interactions ◽  
Diverse Populations ◽  
Major Contributor ◽  
Complex Genetics ◽  
Reference Strains ◽  
Lines Of Evidence

AbstractMutations often have different effects in genetically distinct individuals. Epistasis between mutations and segregating loci is known to be a major contributor to these background effects, but the architecture of these genetic interactions remains largely unknown. Here, we characterize how segregating loci in a cross of two Saccharomyces cerevisiae strains impact growth following the deletion of the histone deacetylase HOS3. The functions of HOS3 are not well understood and historically its deletion has shown little effect on reference strains. However, we map two loci that genetically interact with HOS3 and each other to produce a broad range of responses to the deletion, including near inviability. Although these interactions explain nearly all of the deletion’s expressivity, their penetrance depends on a liability threshold involving at least 11 additional nuclear and mitochondrial loci. Multiple lines of evidence imply the deletion uncovers genetically complex changes in translation and genome stability in the mitochondria, suggesting a novel connection between Hos3-mediated deacetylation and the mitochondria. These results provide a valuable example of the complicated and unexpected mechanisms that can cause background effects in genetically diverse populations, and show how characterization of background effects can provide new insights into gene function.One Sentence SummaryComplex genetics shape a mutation’s penetrance and expressivity.

scholarly journals Rvs161p Interacts with Fus2p to Promote Cell Fusion in Saccharomyces cerevisiae

1998 ◽  
Vol 141 (3) ◽  
pp. 567-584 ◽  
Author(s):  
Valeria Brizzio ◽  
Alison E. Gammie ◽  
Mark D. Rose
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Actin Cytoskeleton ◽  
Fusion Zone ◽  
Cell Fusion ◽  
Direct Role ◽  
Cytoskeletal Organization ◽  
Actin Organization ◽  
The Stability ◽  
Mating Function ◽  
Lines Of Evidence

FUS7 was previously identified by a mutation that causes a defect in cell fusion in a screen for bilateral mating defects. Here we show that FUS7 is allelic to RVS161/END6, a gene implicated in a variety of processes including viability after starvation, endocytosis, and actin cytoskeletal organization. Two lines of evidence indicate that RVS161/END6's endocytic function is not required for cell fusion. First, several other endocytic mutants showed no cell fusion defects. Second, we isolated five function-specific alleles of RVS161/FUS7 that were defective for endocytosis, but not mating, and three alleles that were defective for cell fusion but not endocytosis. The organization of the actin cytoskeleton was normal in the cell fusion mutants, indicating that Rvs161p's function in cell fusion is independent of actin organization. The three to fourfold induction of RVS161 by mating pheromone and the localization of Rvs161p-GFP to the cell fusion zone suggested that Rvs161p plays a direct role in cell fusion. The phenotypes of double mutants, the coprecipitation of Rvs161p and Fus2p, and the fact that the stability of Fus2p was strongly dependent on Rvs161p's mating function lead to the conclusion that Rvs161p is required to interact with Fus2p for efficient cell fusion.

scholarly journals The Rad27 (Fen-1) Nuclease Inhibits Ty1 Mobility in Saccharomyces cerevisiae

Genetics ◽  
2003 ◽  
Vol 163 (1) ◽  
pp. 55-67 ◽  
Author(s):  
Anuradha Sundararajan ◽  
Bum-Soo Lee ◽  
David J Garfinkel
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Genome Stability ◽  
Frameshift Mutation ◽  
Point Mutations ◽  
Maximum Increase ◽  
Gag Protein ◽  
Genomic Element ◽  
The Stability ◽  
Ty1 Mobility

Abstract Although most Ty1 elements in Saccharomyces cerevisiae are competent for retrotransposition, host defense genes can inhibit different steps of the Ty1 life cycle. Here, we demonstrate that Rad27, a structure-specific nuclease that plays an important role in DNA replication and genome stability, inhibits Ty1 at a posttranslational level. We have examined the effects of various rad27 mutations on Ty1 element retrotransposition and cDNA recombination, termed Ty1 mobility. The point mutations rad27-G67S, rad27-G240D, and rad27-E158D that cause defects in certain enzymatic activities in vitro result in variable increases in Ty1 mobility, ranging from 4- to 22-fold. The C-terminal frameshift mutation rad27-324 confers the maximum increase in Ty1 mobility (198-fold), unincorporated cDNA, and insertion at preferred target sites. The null mutation differs from the other rad27 alleles by increasing the frequency of multimeric Ty1 insertions and cDNA recombination with a genomic element. The rad27 mutants do not markedly alter the levels of Ty1 RNA or the TyA1-gag protein. However, there is an increase in the stability of unincorporated Ty1 cDNA in rad27-324 and the null mutant. Our results suggest that Rad27 inhibits Ty1 mobility by destabilizing unincorporated Ty1 cDNA and preventing the formation of Ty1 multimers.

scholarly journals Requirement for Three Novel Protein Complexes in the Absence of the Sgs1 DNA Helicase in Saccharomyces cerevisiae

Genetics ◽  
2001 ◽  
Vol 157 (1) ◽  
pp. 103-118 ◽  
Author(s):  
Janet R Mullen ◽  
Vivek Kaliraman ◽  
Samer S Ibrahim ◽  
Steven J Brill
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Genome Stability ◽  
Protein Complexes ◽  
Ring Finger ◽  
Dna Helicase ◽  
Open Reading Frames ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Dna Helicases ◽  
Cell Extracts

Abstract The Saccharomyces cerevisiae Sgs1 protein is a member of the RecQ family of DNA helicases and is required for genome stability, but not cell viability. To identify proteins that function in the absence of Sgs1, a synthetic-lethal screen was performed. We obtained mutations in six complementation groups that we refer to as SLX genes. Most of the SLX genes encode uncharacterized open reading frames that are conserved in other species. None of these genes is required for viability and all SLX null mutations are synthetically lethal with mutations in TOP3, encoding the SGS1-interacting DNA topoisomerase. Analysis of the null mutants identified a pair of genes in each of three phenotypic classes. Mutations in MMS4 (SLX2) and SLX3 generate identical phenotypes, including weak UV and strong MMS hypersensitivity, complete loss of sporulation, and synthetic growth defects with mutations in TOP1. Mms4 and Slx3 proteins coimmunoprecipitate from cell extracts, suggesting that they function in a complex. Mutations in SLX5 and SLX8 generate hydroxyurea sensitivity, reduced sporulation efficiency, and a slow-growth phenotype characterized by heterogeneous colony morphology. The Slx5 and Slx8 proteins contain RING finger domains and coimmunoprecipitate from cell extracts. The SLX1 and SLX4 genes are required for viability in the presence of an sgs1 temperature-sensitive allele at the restrictive temperature and Slx1 and Slx4 proteins are similarly associated in cell extracts. We propose that the MMS4/SLX3, SLX5/8, and SLX1/4 gene pairs encode heterodimeric complexes and speculate that these complexes are required to resolve recombination intermediates that arise in response to DNA damage, during meiosis, and in the absence of SGS1/TOP3.

scholarly journals Development and Characterization of Two Types of Surface Displayed Levansucrases for Levan Biosynthesis

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 757
Author(s):  
Huiyi Shang ◽  
Danni Yang ◽  
Dairong Qiao ◽  
Hui Xu ◽  
Yi Cao
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Molecular Weight ◽  
Large Scale ◽  
Surface Display ◽  
Yeast Surface Display ◽  
Fusion Partner ◽  
Whole Cell ◽  
Food Industries ◽  
Yeast Surface ◽  
The Stability

Levan has wide applications in chemical, cosmetic, pharmaceutical and food industries. The free levansucrase is usually used in the biosynthesis of levan, but the poor reusability and low stability of free levansucrase have limited its large-scale use. To address this problem, the surface-displayed levansucrase in Saccharomyces cerevisiae were generated and evaluated in this study. The levansucrase from Zymomonas mobilis was displayed on the cell surface of Saccharomyces cerevisiae EBY100 using a various yeast surface display platform. The N-terminal fusion partner is based on a-agglutinin, and the C-terminal one is Flo1p. The yield of levan produced by these two whole-cell biocatalysts reaches 26 g/L and 34 g/L in 24 h, respectively. Meanwhile, the stability of the surface-displayed levansucrases is significantly enhanced. After six reuses, these two biocatalysts retained over 50% and 60% of their initial activities, respectively. Furthermore, the molecular weight and polydispersity test of the products suggested that the whole-cell biocatalyst of levansucrase displayed by Flo1p has more potentials in the production of levan with low molecular weight which is critical in certain applications. In conclusion, our method not only enable the possibility to reuse the enzyme, but also improves the stability of the enzyme.

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