The Ubiquitin Ligase (E3) Psh1p Is Required for Proper Segregation of both Centromeric and Two-Micron Plasmids in Saccharomyces cerevisiae
Protein degradation by the ubiquitin-proteasome system is essential to many processes. We sought to assess its involvement in the turnover of mitochondrial proteins in Saccharomyces cerevisiae. We find that deletion of a specific ubiquitin ligase (E3), Psh1p, increases the abundance of a temperature...
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| Format: | Article |
| Language: | English |
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Oxford University Press
2017-11-01
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| Series: | G3: Genes, Genomes, Genetics |
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| Online Access: | http://g3journal.org/lookup/doi/10.1534/g3.117.300227 |
| _version_ | 1818614201433718784 |
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| author | Meredith B. Metzger Jessica L. Scales Mitchell F. Dunklebarger Allan M. Weissman |
| author_facet | Meredith B. Metzger Jessica L. Scales Mitchell F. Dunklebarger Allan M. Weissman |
| author_sort | Meredith B. Metzger |
| collection | DOAJ |
| description | Protein degradation by the ubiquitin-proteasome system is essential to many processes. We sought to assess its involvement in the turnover of mitochondrial proteins in Saccharomyces cerevisiae. We find that deletion of a specific ubiquitin ligase (E3), Psh1p, increases the abundance of a temperature-sensitive mitochondrial protein, mia40-4pHA, when it is expressed from a centromeric plasmid. Deletion of Psh1p unexpectedly elevates the levels of other proteins expressed from centromeric plasmids. Loss of Psh1p does not increase the rate of turnover of mia40-4pHA, affect total protein synthesis, or increase the protein levels of chromosomal genes. Instead, psh1Δ appears to increase the incidence of missegregation of centromeric plasmids relative to their normal 1:1 segregation. After generations of growth with selection for the plasmid, ongoing missegregation would lead to elevated plasmid DNA, mRNA, and protein, all of which we observe in psh1Δ cells. The only known substrate of Psh1p is the centromeric histone H3 variant Cse4p, which is targeted for proteasomal degradation after ubiquitination by Psh1p. However, Cse4p overexpression alone does not phenocopy psh1Δ in increasing plasmid DNA and protein levels. Instead, elevation of Cse4p leads to an apparent increase in 1:0 plasmid segregation events. Further, 2 μm high-copy yeast plasmids also missegregate in psh1Δ, but not when Cse4p alone is overexpressed. These findings demonstrate that Psh1p is required for the faithful inheritance of both centromeric and 2 μm plasmids. Moreover, the effects that loss of Psh1p has on plasmid segregation cannot be accounted for by increased levels of Cse4p. |
| first_indexed | 2024-12-16T16:14:15Z |
| format | Article |
| id | doaj.art-6bf360f5c7e64a50a9d7fde51015da84 |
| institution | Directory Open Access Journal |
| issn | 2160-1836 |
| language | English |
| last_indexed | 2024-12-16T16:14:15Z |
| publishDate | 2017-11-01 |
| publisher | Oxford University Press |
| record_format | Article |
| series | G3: Genes, Genomes, Genetics |
| spelling | doaj.art-6bf360f5c7e64a50a9d7fde51015da842022-12-21T22:25:08ZengOxford University PressG3: Genes, Genomes, Genetics2160-18362017-11-017113731374310.1534/g3.117.30022716The Ubiquitin Ligase (E3) Psh1p Is Required for Proper Segregation of both Centromeric and Two-Micron Plasmids in Saccharomyces cerevisiaeMeredith B. MetzgerJessica L. ScalesMitchell F. DunklebargerAllan M. WeissmanProtein degradation by the ubiquitin-proteasome system is essential to many processes. We sought to assess its involvement in the turnover of mitochondrial proteins in Saccharomyces cerevisiae. We find that deletion of a specific ubiquitin ligase (E3), Psh1p, increases the abundance of a temperature-sensitive mitochondrial protein, mia40-4pHA, when it is expressed from a centromeric plasmid. Deletion of Psh1p unexpectedly elevates the levels of other proteins expressed from centromeric plasmids. Loss of Psh1p does not increase the rate of turnover of mia40-4pHA, affect total protein synthesis, or increase the protein levels of chromosomal genes. Instead, psh1Δ appears to increase the incidence of missegregation of centromeric plasmids relative to their normal 1:1 segregation. After generations of growth with selection for the plasmid, ongoing missegregation would lead to elevated plasmid DNA, mRNA, and protein, all of which we observe in psh1Δ cells. The only known substrate of Psh1p is the centromeric histone H3 variant Cse4p, which is targeted for proteasomal degradation after ubiquitination by Psh1p. However, Cse4p overexpression alone does not phenocopy psh1Δ in increasing plasmid DNA and protein levels. Instead, elevation of Cse4p leads to an apparent increase in 1:0 plasmid segregation events. Further, 2 μm high-copy yeast plasmids also missegregate in psh1Δ, but not when Cse4p alone is overexpressed. These findings demonstrate that Psh1p is required for the faithful inheritance of both centromeric and 2 μm plasmids. Moreover, the effects that loss of Psh1p has on plasmid segregation cannot be accounted for by increased levels of Cse4p.http://g3journal.org/lookup/doi/10.1534/g3.117.300227ubiquitinationCse4pplasmid missegregationCEN plasmid2 μm plasmid |
| spellingShingle | Meredith B. Metzger Jessica L. Scales Mitchell F. Dunklebarger Allan M. Weissman The Ubiquitin Ligase (E3) Psh1p Is Required for Proper Segregation of both Centromeric and Two-Micron Plasmids in Saccharomyces cerevisiae G3: Genes, Genomes, Genetics ubiquitination Cse4p plasmid missegregation CEN plasmid 2 μm plasmid |
| title | The Ubiquitin Ligase (E3) Psh1p Is Required for Proper Segregation of both Centromeric and Two-Micron Plasmids in Saccharomyces cerevisiae |
| title_full | The Ubiquitin Ligase (E3) Psh1p Is Required for Proper Segregation of both Centromeric and Two-Micron Plasmids in Saccharomyces cerevisiae |
| title_fullStr | The Ubiquitin Ligase (E3) Psh1p Is Required for Proper Segregation of both Centromeric and Two-Micron Plasmids in Saccharomyces cerevisiae |
| title_full_unstemmed | The Ubiquitin Ligase (E3) Psh1p Is Required for Proper Segregation of both Centromeric and Two-Micron Plasmids in Saccharomyces cerevisiae |
| title_short | The Ubiquitin Ligase (E3) Psh1p Is Required for Proper Segregation of both Centromeric and Two-Micron Plasmids in Saccharomyces cerevisiae |
| title_sort | ubiquitin ligase e3 psh1p is required for proper segregation of both centromeric and two micron plasmids in saccharomyces cerevisiae |
| topic | ubiquitination Cse4p plasmid missegregation CEN plasmid 2 μm plasmid |
| url | http://g3journal.org/lookup/doi/10.1534/g3.117.300227 |
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