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Eisenstatt JR, Ohkuni K, Au WC, Preston O, Gliford L, Suva E, Costanzo M, Boone C, Basrai MA. Reduced gene dosage of histone H4 prevents CENP-A mislocalization and chromosomal instability in Saccharomyces cerevisiae. Genetics 2021; 218:6159615. [PMID: 33751052 DOI: 10.1093/genetics/iyab033] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 02/20/2021] [Indexed: 12/14/2022] Open
Abstract
Mislocalization of the centromeric histone H3 variant (Cse4 in budding yeast, CID in flies, CENP-A in humans) to noncentromeric regions contributes to chromosomal instability (CIN) in yeast, fly, and human cells. Overexpression and mislocalization of CENP-A have been observed in cancers, however, the mechanisms that facilitate the mislocalization of overexpressed CENP-A have not been fully explored. Defects in proteolysis of overexpressed Cse4 (GALCSE4) lead to its mislocalization and synthetic dosage lethality (SDL) in mutants for E3 ubiquitin ligases (Psh1, Slx5, SCFMet30, and SCFCdc4), Doa1, Hir2, and Cdc7. In contrast, defects in sumoylation of overexpressed cse4K215/216/A/R prevent its mislocalization and do not cause SDL in a psh1Δ strain. Here, we used a genome-wide screen to identify factors that facilitate the mislocalization of overexpressed Cse4 by characterizing suppressors of the psh1Δ GALCSE4 SDL. Deletions of histone H4 alleles (HHF1 or HHF2), which were among the most prominent suppressors, also suppress slx5Δ, cdc4-1, doa1Δ, hir2Δ, and cdc7-4 GALCSE4 SDL. Reduced dosage of H4 leads to defects in sumoylation and reduced mislocalization of overexpressed Cse4, which contributes to suppression of CIN when Cse4 is overexpressed. We determined that the hhf1-20, cse4-102, and cse4-111 mutants, which are defective in the Cse4-H4 interaction, also exhibit reduced sumoylation of Cse4 and do not display psh1Δ GALCSE4 SDL. In summary, we have identified genes that contribute to the mislocalization of overexpressed Cse4 and defined a role for the gene dosage of H4 in facilitating Cse4 sumoylation and mislocalization to noncentromeric regions, leading to CIN when Cse4 is overexpressed.
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Affiliation(s)
- Jessica R Eisenstatt
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20894, USA
| | - Kentaro Ohkuni
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20894, USA
| | - Wei-Chun Au
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20894, USA
| | - Olivia Preston
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20894, USA
| | - Loran Gliford
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20894, USA
| | - Evelyn Suva
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20894, USA
| | - Michael Costanzo
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 3E1, Canada.,Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Charles Boone
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 3E1, Canada.,Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Munira A Basrai
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20894, USA
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Deposition of Centromeric Histone H3 Variant CENP-A/Cse4 into Chromatin Is Facilitated by Its C-Terminal Sumoylation. Genetics 2020; 214:839-854. [PMID: 32111629 DOI: 10.1534/genetics.120.303090] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 02/26/2020] [Indexed: 12/13/2022] Open
Abstract
Centromeric localization of CENP-A (Cse4 in Saccharomyces cerevisiae, CID in flies, CENP-A in humans) is essential for faithful chromosome segregation. Mislocalization of overexpressed CENP-A contributes to aneuploidy in yeast, flies, and humans, and is proposed to promote tumorigenesis in human cancers. Hence, defining molecular mechanisms that promote or prevent mislocalization of CENP-A is an area of active investigation. In budding yeast, evolutionarily conserved histone chaperones Scm3 and chromatin assembly factor-1 (CAF-1) promote localization of Cse4 to centromeric and noncentromeric regions, respectively. Ubiquitin ligases, such as Psh1 and Slx5, and histone chaperones (HIR complex) regulate proteolysis of overexpressed Cse4 and prevent its mislocalization to noncentromeric regions. In this study, we have identified sumoylation sites lysine (K) 215/216 in the C terminus of Cse4, and shown that sumoylation of Cse4 K215/216 facilitates its genome-wide deposition into chromatin when overexpressed. Our results showed reduced levels of sumoylation of mutant Cse4 K215/216R/A [K changed to arginine (R) or alanine (A)] and reduced interaction of mutant Cse4 K215/216R/A with Scm3 and CAF-1 when compared to wild-type Cse4 Consistent with these results, levels of Cse4 K215/216R/A in the chromatin fraction and localization to centromeric and noncentromeric regions were reduced. Furthermore, in contrast to GAL- CSE4, which exhibits Synthetic Dosage Lethality (SDL) in psh1∆, slx5∆, and hir2∆ strains, GAL- cse4 K215/216R does not exhibit SDL in these strains. Taken together, our results show that deposition of Cse4 into chromatin is facilitated by its C-terminal sumoylation.
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N-terminal Sumoylation of Centromeric Histone H3 Variant Cse4 Regulates Its Proteolysis To Prevent Mislocalization to Non-centromeric Chromatin. G3-GENES GENOMES GENETICS 2018; 8:1215-1223. [PMID: 29432128 PMCID: PMC5873912 DOI: 10.1534/g3.117.300419] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Stringent regulation of cellular levels of evolutionarily conserved centromeric histone H3 variant (CENP-A in humans, CID in flies, Cse4 in yeast) prevents its mislocalization to non-centromeric chromatin. Overexpression and mislocalization of CENP-A has been observed in cancers and leads to aneuploidy in yeast, flies, and human cells. Ubiquitin-mediated proteolysis of Cse4 by E3 ligases such as Psh1 and Sumo-Targeted Ubiquitin Ligase (STUbL) Slx5 prevent mislocalization of Cse4. Previously, we identified Siz1 and Siz2 as the major E3 ligases for sumoylation of Cse4. In this study, we have identified lysine 65 (K65) in Cse4 as a site that regulates sumoylation and ubiquitin-mediated proteolysis of Cse4 by Slx5. Strains expressing cse4 K65R exhibit reduced levels of sumoylated and ubiquitinated Cse4 in vivo. Furthermore, co-immunoprecipitation experiments reveal reduced interaction of cse4 K65R with Slx5, leading to increased stability and mislocalization of cse4 K65R under normal physiological conditions. Based on the increased stability of cse4 K65R in psh1∆ strains but not in slx5∆ strains, we conclude that Slx5 targets sumoylated Cse4 K65 for ubiquitination-mediated proteolysis independent of Psh1. In summary, we have identified and characterized the physiological role of Cse4 K65 in sumoylation, ubiquitin-mediated proteolysis, and localization of Cse4 for genome stability.
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Functional characterization of a type 2 metallothionein gene, SsMT2, from alkaline-tolerant Suaeda salsa. Sci Rep 2017; 7:17914. [PMID: 29263347 PMCID: PMC5738349 DOI: 10.1038/s41598-017-18263-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 11/22/2017] [Indexed: 11/08/2022] Open
Abstract
A type 2 metallothionein gene, SsMT2, was cloned from Suaeda salsa, a salt- and alkali-tolerant plant, which is dominant species on the saline/alkali soil of northeast China. The SsMT2 gene was expressed in all organs except the flower and its expression was induced by various stresses such as CdCl2, NaCl, NaHCO3, and H2O2 treatments. SsMT2-transgenic yeast (Saccharomyces cerevisiae) and plants (Arabidopsis thaliana) showed significantly increased resistance to metal, salt and oxidant stresses. These transgenics accumulated more Cd2+, but less Na+ than their wild type counterparts. SsMT2 transgenic Arabidopsis maintained lower level of H2O2 than wild type plants did in response to the stress treatments. These results demonstrated that the SsMT2 gene plays an important role in reactive oxygen species scavenging and confers enhanced metal and oxidant tolerance to plants.
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Ohkuni K, Takahashi Y, Fulp A, Lawrimore J, Au WC, Pasupala N, Levy-Myers R, Warren J, Strunnikov A, Baker RE, Kerscher O, Bloom K, Basrai MA. SUMO-Targeted Ubiquitin Ligase (STUbL) Slx5 regulates proteolysis of centromeric histone H3 variant Cse4 and prevents its mislocalization to euchromatin. Mol Biol Cell 2016; 27:mbc.E15-12-0827. [PMID: 26960795 PMCID: PMC4850037 DOI: 10.1091/mbc.e15-12-0827] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 02/17/2016] [Accepted: 03/03/2016] [Indexed: 12/14/2022] Open
Abstract
Centromeric histone H3, CENP-ACse4, is essential for faithful chromosome segregation. Stringent regulation of cellular levels of CENP-ACse4 restricts its localization to centromeres. Mislocalization of CENP-ACse4 is associated with aneuploidy in yeast, flies and tumorigenesis in human cells; thus, defining pathways that regulate CENP-A levels is critical for understanding how mislocalization of CENP-A contributes to aneuploidy in human cancers. Previous work in budding yeast has shown that ubiquitination of overexpressed Cse4 by Psh1, an E3 ligase, partially contributes to proteolysis of Cse4. Here, we provide the first evidence that Cse4 is sumoylated by E3 ligases Siz1 and Siz2 in vivo and in vitro. Ubiquitination of Cse4 by Small Ubiquitin-related Modifier (SUMO)-Targeted Ubiquitin Ligase (STUbL) Slx5 plays a critical role in proteolysis of Cse4 and prevents mislocalization of Cse4 to euchromatin under normal physiological conditions. Accumulation of sumoylated Cse4 species and increased stability of Cse4 in slx5∆ strains suggest that sumoylation precedes ubiquitin-mediated proteolysis of Cse4. Slx5-mediated Cse4 proteolysis is independent of Psh1 since slx5∆ psh1∆ strains exhibit higher levels of Cse4 stability and mislocalization compared to either slx5∆ or psh1∆ strains. Our results demonstrate a role for Slx5 in ubiquitin-mediated proteolysis of Cse4 to prevent its mislocalization and maintain genome stability.
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Affiliation(s)
- Kentaro Ohkuni
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Yoshimitsu Takahashi
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Alyona Fulp
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Josh Lawrimore
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Wei-Chun Au
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Nagesh Pasupala
- Biology Department, The College of William & Mary, Williamsburg, VA 23187
| | - Reuben Levy-Myers
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
- Biology Department, The College of William & Mary, Williamsburg, VA 23187
| | - Jack Warren
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | | | - Richard E. Baker
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01655
| | - Oliver Kerscher
- Biology Department, The College of William & Mary, Williamsburg, VA 23187
| | - Kerry Bloom
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Munira A. Basrai
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
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