The Ubiquitin Ligase (E3) Psh1p Is Required for Proper Segregation of both Centromeric and Two-Micron Plasmids in <i>Saccharomyces cerevisiae</i>

Metzger, Meredith B.; Scales, Jessica L.; Dunklebarger, Mitchell; Weissman, Allan M.

doi:10.1534/g3.117.300227

Cited by 8 publications

(7 citation statements)

References 70 publications

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“…We did not observe a significant difference in plasmid retention for hir2D (65%) when compared to the psh1D hir2D (58%) strain (Figure 7G). Previous studies have also reported plasmid retention defects in a psh1D strain (Herrero and Thorpe 2016;Metzger et al 2017). Taken together, our results show that Hir2 facilitates the interaction of Cse4 with Psh1, and this may contribute to the increased plasmid loss in hir2D strains.…”

Section: Hir2 Interacts With Cse4 and Facilitates The Interaction Of Cse4 With Psh1 To Promote Cse4 Proteolysissupporting

confidence: 82%

A Genome-Wide Screen Reveals a Role for the HIR Histone Chaperone Complex in Preventing Mislocalization of Budding Yeast CENP-A

Ciftci-Yilmaz

Mishra

et al. 2018

Genetics

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Centromeric localization of the evolutionarily conserved centromere-specific histone H3 variant CENP-A (Cse4 in yeast) is essential for faithful chromosome segregation. Overexpression and mislocalization of CENP-A lead to chromosome segregation defects in yeast, flies, and human cells. Overexpression of CENP-A has been observed in human cancers; however, the molecular mechanisms preventing CENP-A mislocalization are not fully understood. Here, we used a genome-wide synthetic genetic array (SGA) to identify gene deletions that exhibit synthetic dosage lethality (SDL) when Cse4 is overexpressed. Deletion for genes encoding the replication-independent histone chaperone HIR complex (, ,, ) and a Cse4-specific E3 ubiquitin ligase,, showed highest SDL. We defined a role for Hir2 in proteolysis of Cse4 that prevents mislocalization of Cse4 to noncentromeric regions for genome stability. Hir2 interacts with Cse4 , and strains exhibit defects in Cse4 proteolysis and stabilization of chromatin-bound Cse4 Mislocalization of Cse4 to noncentromeric regions with a preferential enrichment at promoter regions was observed in strains. We determined that Hir2 facilitates the interaction of Cse4 with Psh1, and that defects in Psh1-mediated proteolysis contribute to increased Cse4 stability and mislocalization of Cse4 in the strain. In summary, our genome-wide screen provides insights into pathways that regulate proteolysis of Cse4 and defines a novel role for the HIR complex in preventing mislocalization of Cse4 by facilitating proteolysis of Cse4, thereby promoting genome stability.

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Section: Hir2 Interacts With Cse4 and Facilitates The Interaction Of Cse4 With Psh1 To Promote Cse4 Proteolysissupporting

confidence: 82%

A Genome-Wide Screen Reveals a Role for the HIR Histone Chaperone Complex in Preventing Mislocalization of Budding Yeast CENP-A

Ciftci-Yilmaz

Mishra

et al. 2018

Genetics

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“…Similarly to these studies, we show that a number of plasmid copies may increase in selective conditions and confer adaptation to mutations in release factor genes ( Figure 2 ). In one of the recent works, it has been shown that the PSH1 gene controls plasmid segregation and copy number [ 43 ]. Hence, it may be hypothesized that the activity of this gene contributes to the phenomenon of adaptation investigated in our work.…”

Section: Discussionmentioning

confidence: 99%

Gene Amplification as a Mechanism of Yeast Adaptation to Nonsense Mutations in Release Factor Genes

Maksiutenko

Barbitoff

Matveenko

et al. 2021

Genes

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Protein synthesis (translation) is one of the fundamental processes occurring in the cells of living organisms. Translation can be divided into three key steps: initiation, elongation, and termination. In the yeast Saccharomyces cerevisiae, there are two translation termination factors, eRF1 and eRF3. These factors are encoded by the SUP45 and SUP35 genes, which are essential; deletion of any of them leads to the death of yeast cells. However, viable strains with nonsense mutations in both the SUP35 and SUP45 genes were previously obtained in several groups. The survival of such mutants clearly involves feedback control of premature stop codon readthrough; however, the exact molecular basis of such feedback control remain unclear. To investigate the genetic factors supporting the viability of these SUP35 and SUP45 nonsense mutants, we performed whole-genome sequencing of strains carrying mutant sup35-n and sup45-n alleles; while no common SNPs or indels were found in these genomes, we discovered a systematic increase in the copy number of the plasmids carrying mutant sup35-n and sup45-n alleles. We used the qPCR method which confirmed the differences in the relative number of SUP35 and SUP45 gene copies between strains carrying wild-type or mutant alleles of SUP35 and SUP45 genes. Moreover, we compare the number of copies of the SUP35 and SUP45 genes in strains carrying different nonsense mutant variants of these genes as a single chromosomal copy. qPCR results indicate that the number of mutant gene copies is increased compared to the wild-type control. In case of several sup45-n alleles, this was due to a disomy of the entire chromosome II, while for the sup35-218 mutation we observed a local duplication of a segment of chromosome IV containing the SUP35 gene. Taken together, our results indicate that gene amplification is a common mechanism of adaptation to nonsense mutations in release factor genes in yeast.

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“…Deletion of PSH1 or CKA2 , one of the two catalytic subunits of CK2, resulted in poor growth when Cse4 was overexpressed and higher levels of Cse4 incorporation at non-centromeric sites ( 10–12 ). Deletion of PSH1 with overexpression of Cse4 could potentially affect kinetochore function, and consistently, Psh1 may contribute to plasmid segregation ( 45 ), but this does not seem to fully explain the growth defect ( 11 , 46 ). If part of the growth defect is due to disruption of chromatin-based processes from misincorporation of Cse4, and CAF-1 is responsible for targeting Cse4 into ectopic chromosome regions, then deletion of CAF-1 subunits might rescue the slow growth observed upon Cse4 overexpression in psh1Δ and cka2Δ strains.…”

Section: Resultsmentioning

confidence: 99%

Chromatin assembly factor-1 (CAF-1) chaperone regulates Cse4 deposition into chromatin in budding yeast

Hewawasam

Dhatchinamoorthy

Mattingly

et al. 2018

Nucleic Acids Research

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Correct localization of the centromeric histone variant CenH3/CENP-A/Cse4 is an important part of faithful chromosome segregation. Mislocalization of CenH3 could affect chromosome segregation, DNA replication and transcription. CENP-A is often overexpressed and mislocalized in cancer genomes, but the underlying mechanisms are not understood. One major regulator of Cse4 deposition is Psh1, an E3 ubiquitin ligase that controls levels of Cse4 to prevent deposition into non-centromeric regions. We present evidence that Chromatin assembly factor-1 (CAF-1), an evolutionarily conserved histone H3/H4 chaperone with subunits shown previously to interact with CenH3 in flies and human cells, regulates Cse4 deposition in budding yeast. yCAF-1 interacts with Cse4 and can assemble Cse4 nucleosomes in vitro. Loss of yCAF-1 dramatically reduces the amount of Cse4 deposited into chromatin genome-wide when Cse4 is overexpressed. The incorporation of Cse4 genome-wide may have multifactorial effects on growth and gene expression. Loss of yCAF-1 can rescue growth defects and some changes in gene expression associated with Cse4 deposition that occur in the absence of Psh1-mediated proteolysis. Incorporation of Cse4 into promoter nucleosomes at transcriptionally active genes depends on yCAF-1. Overall our findings suggest CAF-1 can act as a CenH3 chaperone, regulating levels and incorporation of CenH3 in chromatin.

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The Ubiquitin Ligase (E3) Psh1p Is Required for Proper Segregation of both Centromeric and Two-Micron Plasmids in Saccharomyces cerevisiae

Cited by 8 publications

References 70 publications

A Genome-Wide Screen Reveals a Role for the HIR Histone Chaperone Complex in Preventing Mislocalization of Budding Yeast CENP-A

A Genome-Wide Screen Reveals a Role for the HIR Histone Chaperone Complex in Preventing Mislocalization of Budding Yeast CENP-A

Gene Amplification as a Mechanism of Yeast Adaptation to Nonsense Mutations in Release Factor Genes

Chromatin assembly factor-1 (CAF-1) chaperone regulates Cse4 deposition into chromatin in budding yeast

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