Fub1p, a Novel Protein Isolated by Boundary Screening, Binds the Proteasome Complex

Genes Genet Syst. 2011;86(5):305-14. doi: 10.1266/ggs.86.305.


Silenced chromatin domains are restricted to specific regions. Eukaryotic chromosomes are organized into discrete domains delimited by domain boundaries. From approximately 6,000 genes in Saccharomyces cerevisiae, we previously isolated 55 boundary genes. In this study, we focus on the molecular function of one of boundary genes, YCR076C/FUB1 (function of boundary), whose function has not been clearly defined in vivo. Biochemical analysis of Fub1p revealed that it interacted with multiple subunits of the 20S proteasome core particle (20S CP). To further clarify the functional link between Fub1p and proteasome, several proteasome mutants were analyzed. Although only 20S CP subunits were isolated as Fub1p interactors, a genetic interaction was also observed for component of 19S regulatory particle (19S RP) suggesting involvement of Fub1p with the whole proteasome. We also analyzed the mechanism of boundary establishment by using proteasome composition factor-deficient strains. Deletion of pre9 and ump1, whose products have effects on the 20S CP, resulted in a decrease in boundary function. Domain analyses of Fub1p identified a minimum functional domain in the C terminus that was essential for boundary establishment and showed a limited sequence homology to the human PSMF1, which is known to inhibit proteasome activity. Finally, boundary assay showed that human PSMF1 also exhibited boundary establishment activity in yeast. Our results defined the functional correlation between Fub1p and PSMF1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylation
  • DNA-Binding Proteins / metabolism*
  • Gene Silencing / physiology*
  • Histones / metabolism
  • Mass Spectrometry
  • Models, Genetic*
  • Proteasome Endopeptidase Complex / genetics
  • Proteasome Endopeptidase Complex / metabolism*
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Silent Information Regulator Proteins, Saccharomyces cerevisiae / metabolism
  • Sirtuin 2 / metabolism
  • Transcription Factors / metabolism*


  • DNA-Binding Proteins
  • Fub1 protein, S cerevisiae
  • GAL4 protein, S cerevisiae
  • Histones
  • Saccharomyces cerevisiae Proteins
  • Silent Information Regulator Proteins, Saccharomyces cerevisiae
  • Transcription Factors
  • Proteasome Endopeptidase Complex
  • SIR2 protein, S cerevisiae
  • Sirtuin 2