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

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


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Centromere / metabolism
  • Centromere Protein A / genetics
  • Centromere Protein A / metabolism*
  • Chromatin / metabolism
  • Chromosomal Proteins, Non-Histone / genetics*
  • Chromosomal Proteins, Non-Histone / metabolism*
  • Chromosome Segregation
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / metabolism*
  • Genome-Wide Association Study
  • Histone Chaperones / genetics
  • Histone Chaperones / metabolism
  • Histones / metabolism
  • Kinetochores / metabolism
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Protein Binding
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae Proteins / genetics*
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Saccharomycetales / metabolism
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitination


  • CSE4 protein, S cerevisiae
  • Centromere Protein A
  • Chromatin
  • Chromosomal Proteins, Non-Histone
  • DNA-Binding Proteins
  • HIR1 protein, S cerevisiae
  • HIR2 protein, S cerevisiae
  • Histone Chaperones
  • Histones
  • Nuclear Proteins
  • Repressor Proteins
  • Saccharomyces cerevisiae Proteins
  • Ubiquitin-Protein Ligases