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Genetics. 2018 Sep;210(1):203-218. doi: 10.1534/genetics.118.301305. Epub 2018 Jul 16.

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

Author information

1
Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.
2
National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894.
3
Department of Computer Science and Engineering, University of Minnesota-Twin Cities, Minneapolis, Minnesota 55455.
4
Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Ontario M5S 3E1, Canada.
5
Lewis-Sigler Institute for Integrative Genomics, Princeton University, New Jersey 08544.
6
Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01655.
7
Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892 basraim@mail.nih.gov.

Abstract

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 (HIR1, HIR2, HIR3, HPC2) and a Cse4-specific E3 ubiquitin ligase, PSH1, 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 in vivo, and hir2∆ 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 hir2∆ 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 hir2∆ 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.

KEYWORDS:

CENP-A; Cse4; centromere; chromosome segregation; gene regulation; histone chaperone; histones; kinetochore

PMID:
30012561
PMCID:
PMC6116949
DOI:
10.1534/genetics.118.301305
[Indexed for MEDLINE]
Free PMC Article

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